29 Minor Planet Bulletin 31 (2004) THE MINOR PLANET BULLETIN VOLUME 31, NUMBER 2, A.D. 2004 APRIL-JUNE 29. CCD OBSERVATIONS AND PERIOD DETERMINATION OF FIFTEEN MINOR PLANETS Kevin Ivarsen Sarah Willis Laura Ingleby Dan Matthews Melanie Simet Department of Physics and Astronomy Van Allen Hall University of Iowa Iowa City, IA 52242 [email protected](Received: 17 November Revised: 15 February) We have determined the periods of fifteen minor planets using differential photometry. Eleven of these minor planets had unknown periods, one had an uncertain period, and three had well-known periods. We observed a minimum of two epochs for each object in order to construct composite lightcurves. The periods ranged from 3.7 to 15.2 hours. The objects we report results for are: 174 Phaedra, 228 Agathe, 342 Endymion, 354 Eleonora, 365 Corduba, 373 Melusina, 575 Renate, 1084 Tamariwa, 1171 Rusthawelia, 1388 Aphrodite, 1501 Baade, 1544 Vinterhanseni, 1645 Waterfield, 1799 Koussevitzky, and 2097 Galle. We observed several minor planets from September 27 to October 21, 2003 using the Rigel Telescope (MPC Code 857; see http://phobos.physics.uiowa.edu/tech/rigel.html) at the Winer Observatory near Sonoita, Arizona (31° 39’ N 110° 37’ W). The Rigel Telescope is a robotic facility operated remotely by faculty and students at the University of Iowa for research and educational use. We chose a site in Arizona because of the favorable seeing conditions (2.5 to 3.5 arcsecond FWHM) and the number of clear nights per year. The telescope is scheduled nightly and controlled over the Internet. The telescope is a 37 cm f/14 classical Cassegrain with a 16-bit CCD camera. The camera is an FLI IMG-1024 with a backside illuminated CCD sensor. In this telescope configuration the camera has an image scale of 1 arcsecond per pixel. A signal to noise estimate for 30-second exposures is shown in Figure 1. Most of the images were taken using a Johnson-Cousins photometric R (red) filter, although some observations required a C (clear glass) filter for an improved signal-to-noise ratio. In general we selected asteroids that did not have periods listed in an October 2003 revision of the list of Harris (2003) and that would be near opposition at the time of observation. At the beginning of this project, eleven of the asteroids had undetermined periods. However, by the project’s completion asteroids 1645 Waterfield and 228 Agathe were being studied by other astronomers as posted on the CALL website (http://www.minorplanetobserver.com/astlc/default.htm). Monson (2004) presents a preliminary period determination for 1645 Waterfield that agrees with our data. No result for 228 had been released at the time this paper was reviewed. To ensure the quality and accuracy of our experimental method, we observed four asteroids with existing entries in the Harris list and confirmed their periods. These asteroids are 174 Phaedra, 354 Eleonora, 575 Renate, and 1084 Tamariwa. Asteroid 1084 Tamariwa previously had two reported periods of 6.153 hours and 7.08 hours. Our initial period estimate matched the 7.08 hour result, although this resulted in a very noisy combined lightcurve. Further analysis revealed 6.19 hours as being a much better result. We believe that the 7.08 hour period estimate can be discounted with a high level of confidence. Information about each epoch of observation is displayed in Table I. Our results are summarized in Table II, and our lightcurves are shown in the Appendix. Additional information and data for all of our observations may be obtained from our website, http://phobos.physics.uiowa.edu/research/asteroids. Our results may also be found on the CALL website. We thank Alan Harris for his careful review of the first draft of this paper. References Harris, A. W. (2003). http://cfa-www.harvard.edu/iau/lists/Light curveDat.html Monson, A. (2004). http://krypton.mnsu.edu/~monsoa1/welcome_files/Asteroid.htm EDITOR’S NOTE: The team of Ivarsen et al. are to be congratulated for their prolific results accomplished using a robotic telescope at a distant favorable location. Their results clearly demonstrate the highly productive capabilities of such systems for asteroid lightcurve work. BULLETIN OF THE MINOR PLANETS SECTION OF THE ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS
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Minor Planet Bulletin 31 (2004)
THE MINOR PLANETBULLETIN
VOLUME 31, NUMBER 2, A.D. 2004 APRIL-JUNE 29.
CCD OBSERVATIONS AND PERIOD DETERMINATIONOF FIFTEEN MINOR PLANETS
Kevin IvarsenSarah Willis
Laura InglebyDan MatthewsMelanie Simet
Department of Physics and Astronomy Van Allen Hall
We have determined the periods of fifteen minor planetsusing differential photometry. Eleven of these minorplanets had unknown periods, one had an uncertainperiod, and three had well-known periods. We observeda minimum of two epochs for each object in order toconstruct composite lightcurves. The periods rangedfrom 3.7 to 15.2 hours. The objects we report results forare: 174 Phaedra, 228 Agathe, 342 Endymion, 354Eleonora, 365 Corduba, 373 Melusina, 575 Renate,1084 Tamariwa, 1171 Rusthawelia, 1388 Aphrodite,1501 Baade, 1544 Vinterhanseni, 1645 Waterfield, 1799Koussevitzky, and 2097 Galle.
We observed several minor planets from September 27 to October21, 2003 using the Rigel Telescope (MPC Code 857; seehttp://phobos.physics.uiowa.edu/tech/rigel.html) at the WinerObservatory near Sonoita, Arizona (31° 39’ N 110° 37’ W). TheRigel Telescope is a robotic facility operated remotely by facultyand students at the University of Iowa for research and educationaluse. We chose a site in Arizona because of the favorable seeingconditions (2.5 to 3.5 arcsecond FWHM) and the number of clearnights per year. The telescope is scheduled nightly and controlledover the Internet.
The telescope is a 37 cm f/14 classical Cassegrain with a 16-bitCCD camera. The camera is an FLI IMG-1024 with a backsideilluminated CCD sensor. In this telescope configuration thecamera has an image scale of 1 arcsecond per pixel. A signal tonoise estimate for 30-second exposures is shown in Figure 1.Most of the images were taken using a Johnson-Cousins
photometric R (red) filter, although some observations required aC (clear glass) filter for an improved signal-to-noise ratio.
In general we selected asteroids that did not have periods listed inan October 2003 revision of the list of Harris (2003) and thatwould be near opposition at the time of observation. At thebeginning of this project, eleven of the asteroids had undeterminedperiods. However, by the project’s completion asteroids 1645Waterfield and 228 Agathe were being studied by otherastronomers as posted on the CALL website(http://www.minorplanetobserver.com/astlc/default.htm). Monson(2004) presents a preliminary period determination for 1645Waterfield that agrees with our data. No result for 228 had beenreleased at the time this paper was reviewed.
To ensure the quality and accuracy of our experimental method,we observed four asteroids with existing entries in the Harris listand confirmed their periods. These asteroids are 174 Phaedra, 354Eleonora, 575 Renate, and 1084 Tamariwa. Asteroid 1084Tamariwa previously had two reported periods of 6.153 hours and7.08 hours. Our initial period estimate matched the 7.08 hourresult, although this resulted in a very noisy combined lightcurve.Further analysis revealed 6.19 hours as being a much better result.We believe that the 7.08 hour period estimate can be discountedwith a high level of confidence.
Information about each epoch of observation is displayed inTable I. Our results are summarized in Table II, and ourlightcurves are shown in the Appendix. Additional informationand data for all of our observations may be obtained from ourwebsite, http://phobos.physics.uiowa.edu/research/asteroids. Ourresults may also be found on the CALL website.
We thank Alan Harris for his careful review of the first draft ofthis paper.
References
Harris, A. W. (2003). http://cfa-www.harvard.edu/iau/lists/LightcurveDat.html
Monson, A. (2004).http://krypton.mnsu.edu/~monsoa1/welcome_files/Asteroid.htm
EDITOR’S NOTE: The team of Ivarsen et al. are to becongratulated for their prolific results accomplished using arobotic telescope at a distant favorable location. Their resultsclearly demonstrate the highly productive capabilities of suchsystems for asteroid lightcurve work.
BULLETIN OF THE MINOR PLANETS SECTION OF THEASSOCIATION OF LUNAR AND PLANETARY OBSERVERS
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Table I – Observation details
Ast# Epoch Filter Exposure #Images Mag 174 01 Oct 03 R 15 84 13.0 174 11 Oct 03 R 30 38 12.8 174 15 Oct 03 R 30 49 12.8 174 16 Oct 03 R 30 38 12.5 174 17 Oct 03 R 30 54 12.5 228 16 Oct 03 R 30 39 13.5 228 17 Oct 03 R 30 60 13.4 228 21 Oct 03 R 30 38 13.6 342 13 Oct 03 R 30 62 12.6 342 14 Oct 03 R 30 62 12.5 342 16 Oct 03 R 15 27 12.8 342 19 Oct 03 R 30 58 12.8 354 01 Oct 03 R 30 37 11.0 354 13 Oct 03 R 30 38 11.5 354 14 Oct 03 R 30 35 11.4 354 16 Oct 03 R 15 14 11.5 354 19 Oct 03 R 30 32 11.7 365 27 Sep 03 C 15 133 12.8 365 28 Sep 03 R 30 56 12.3 365 16 Oct 03 R 30 42 12.6 373 29 Sep 03 R 15 68 13.6 373 13 Oct 03 R 15 23 14.0 373 14 Oct 03 R 15 16 13.6 373 15 Oct 03 R 15 44 13.9 575 27 Sep 03 C 15 131 13.7 575 28 Sep 03 R 30 54 13.8 575 29 Sep 03 R 30 69 14.11084 12 Oct 03 R 15 10 14.11084 13 Oct 03 R 15 10 13.91084 14 Oct 03 R 15 43 13.51084 17 Oct 03 R 15 67 14.11171 19 Oct 03 R 15 84 13.41171 20 Oct 03 R 15 41 13.01388 01 Oct 03 R 15 36 15.31388 02 Oct 03 R 30 31 15.41388 13 Oct 03 R 30 44 15.41388 14 Oct 03 R 30 47 15.61388 15 Oct 03 R 15 34 15.81388 19 Oct 03 R 30 45 16.01501 14 Oct 03 R 15 47 13.71501 15 Oct 03 R 15 49 13.91501 17 Oct 03 R 15 73 14.01544 13 Oct 03 R 30 55 15.21544 14 Oct 03 R 30 53 15.01544 15 Oct 03 R 15 35 15.01544 16 Oct 03 R 15 29 15.31544 19 Oct 03 R 30 53 15.61645 16 Oct 03 R 30 59 14.21645 17 Oct 03 C 20 100 14.41799 01 Oct 03 R 15 64 15.41799 02 Oct 03 R 20 47 15.31799 16 Oct 03 R 30 38 15.71799 17 Oct 03 C 20 45 15.62097 30 Sep 03 R 30 98 14.62097 11 Oct 03 R 30 50 15.52097 15 Oct 03 R 30 50 15.42097 17 Oct 03 R 30 55 15.2
This is a report on the lightcurve measurement programat Antelope Hills Observatory in the United States.Asteroid 1474 Beira was determined to have a period of4.184 hours ± 0.001 hours, with an amplitude of 0.18 ±0.02 magnitude. Asteroid 3674 Erbisbuhl exhibited aperiod of 11.28 hours ±0.01 hours and an amplitude of0.40 ± 0.02 magnitude.
Equipment and Procedure
In 2002, Antelope Hills Observatory was established as areplacement for Thornton Observatory, MPC code 713. The newobservatory is located near Bennett, Colorado at an elevation of1740 meters. The observatory has obtained the MPC code H09.The equipment and instrumentation of Antelope Hills Observatoryconsists of an 0.25-m f/10 Meade SCT telescope, a TrueTechnology filter wheel, and an Apogee AP47 camera, operatedunbinned. The instruments are housed in a clamshell dome, andare operated remotely from the nearby house. Targets wereselected from the “Potential Lightcurve Targets” on the CALLwebsite (Warner, 2003), and further refined based on theirmagnitude and position in the sky. Targets were selected for whichno lightcurve data had been previously reported. (Harris, 1997).Mars-crossing asteroids were given priority.
All images reported here were obtained in unfiltered light, using aclear filter with an IR cutoff of 700 nm to prevent fringing. Thedifferential photometry was measured using the program“Canopus” by Brian Warner, which uses aperture photometry.Magnitudes were calculated using reference stars from the USNO-A 2.0 catalog. Comparison stars differed from night-to-night dueto movement of the asteroid. Lightcurves were prepared using“Canopus”, based on the method developed by Dr. Alan Harris
(Harris et al., 1989). This program allows compensation for night-to-night comparison star variation by manually shifting individualnight’s magnitude scales to obtain a best fit.
Observations and Results
1474 Beira
Beira, a Mars-crossing asteroid, was discovered August 20, 1935by C. Jackson at Johannesburg, S. A. It is approximately 19 kmin diameter. The aphelion is 4.072 AU and the perihelion is1.400 AU. No lightcurve results are reported for this object(Harris 2004). Observations were made on six nights during theperiod from September 2, 2003 to November 12, 2003. Duringthe period of the investigation, the phase angle dropped from 35.5degrees to 34.0 degrees before increasing to 40.75 degrees.Exposure times for this investigation were two minutes each.Images were taken at 2.5-minute intervals. Dark frames and flatfields were used to calibrate each image. A total of 463observations were used in the solution.
Figure 1 shows the resulting lightcurve. The zero point of thecurve is J.D. 2452887.72249. The synodic period was determinedto be 4.184 hours with a formal error of ± 0.001 hours. Theamplitude was 0.18 ± 0.02 magnitude.
Figure 1. Lightcurve of 1474 Beira, based on a period of 4.184hours. Ordinate is relative magnitude.
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3674 Erbisbuhl
Erbisbuhl is a Mars-crossing asteroid discovered September 13,1963 by C. Hoffmeister at Sonneberg. It is approximately 25 kmin diameter. The aphelion is 3.243 AU, and perihelion is 1.479AU. No previously observed lightcurve is reported for this object(Harris 2004). Observations were made on three nights during theperiod from December 17, 2003 to December 26, 2003. Duringthe period of the investigation, the phase angle dropped from 15.5degrees to 11.0 degrees. Exposure times for this investigationwere two minutes each. Images were taken at 2.5-minuteintervals. Dark frames and flat fields were used to calibrate eachimage. A total of 492 observations were used in the solution.
Figure 2 shows the resulting lightcurve. The zero point of thecurve is J.D. 2452990.75470. The synodic period was determinedto be 11.28 hours with a formal error of ± 0.01 hours. Theamplitude was 0.40 ± 0.02 magnitude. In addition to the clearfilter images used in the period solution, four images were takenusing V and R filters, and transformed to the standard system.The resultant V-R for asteroid 3647 was 0.47 with an estimatederror of ±0.05.
Figure 2. Lightcurve of 3674 Erbisbuhl, based on a period of11.28 hours. Ordinate is relative magnitude.
Acknowledgments
Many thanks to Brian Warner for his continuing work on theCALL website and the program “Canopus”, which has made itpossible for amateurs to analyze and share lightcurve data.
References
Harris, A. W., Young, J. W., Bowell, E., Martin, L. J., Millis, R.L., Poutanen, M., Scaltriti, F., Zappala, V., Schober, H. J.,Debehogne, H., and Zeigler, K. W. (1989). “PhotoelectricObservations of Asteroids 3, 24, 60, 261, and 863.” Icarus 77, pp.171-186.
Harris, A. W. (2004). “Minor Planet Lightcurve Parameters”, Onthe Minor Planet Center website: http://cfa-www.harvard.edu/iau/lists/LightcurveDat.html, or on the CALL website:http://www.MinorPlanetObserver.com/astlc/default.htm
Warner, B. D. (2003). “Potential Lightcurve Targets”, on theCALL website, http://www.MinorPlanetObserver.com/astlc/default.htm
LIGHTCURVE ANALYSIS OF ASTEROIDS110, 196, 776, 804, AND 1825
Lightcurve period and amplitude results are reported forfive asteroids observed at Carbuncle Hill Observatoryduring November 2003 through January 2004. Thefollowing synodic periods and amplitudes weredetermined: 110 Lydia, 10.924+0.003h, 0.14+0.01m;1 9 6 P h i l o m e l a , 8 . 3 3 + 0 . 0 2 h , 0 . 1 0+0.02m;776 Berbericia, 7.67+0.04h, 0.26+0.01m; 804 Hispania,14.64+0.01h, 0.20+0.02m; 1825 Klare, 4.744+0.009h,0.75+0.02m
Introduction
Carbuncle Hill Observatory, MPC code 100, is located abouttwenty miles west of Providence, RI, in one of the darkest spots inthe state. All observations were made using an SBIG ST-10XMECCD camera, binned 3x3, coupled to a 0.35m f6.5 SCT. Thiscombination produced an image dimension of 21x14 arc min. Allobservations were taken through the “clear” filter.
Most of the selected asteroids were observed as part of theA.L.P.O. Shape Modeling Program. Details of this program maybe found at http://www.bitnik.com/mp/alpo/. The aim of theprogram is to determine the pole position, shape, rotation state andsurface scattering properties of asteroids. Lightcurves generatedover several apparitions are generally required to make thesedeterminations. The four asteroids selected for this study alreadyhad previously measured periods, so it is the differences betweenthe newly-found lightcurves and those which preceded them that issignificant. Targets were also selected based on their locationabove the local horizon, as well as for their suitability to theequipment. 1825 Klare was selected from the “Call” website’s“List of Potential Lightcurve Targets” (Warner 2003). This targetdid not have its period published in the list of “Minor PlanetLightcurve Parameters” maintained by Harris and Warner (2003).
Image calibration via dark frames and flat field frames wasperformed using “MaxIm DL”. Lightcurve construction andanalysis was accomplished using “Canopus” developed by BrianWarner. Differential photometry was used in all cases, and allmeasurements were corrected for light travel time.
Observations and Results
110 Lydia
Discovered by A. Borrelly at Marseille in 1870, 110 Lydia wasdetermined to have a synodic period of 10.924+0.003h, with anamplitude of 0.14+0.01m. 597 images taken in ten sessionsbetween December 2 and December 29, 2003 were used to makethis measurement. The lightcurve is shown in Figure 1. Thisperiod is compared to 10.927h, with an amplitude ranging between0.10 and 0.20m, which is presented in the list of Minor PlanetLightcurve Parameters, Harris and Warner (2003). The IRAS
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Minor Planet Survey, as appears in the Small Bodies Node ofNASA’s Planetary Data System, (henceforth IRAS V4.0), lists110 Lydia as having an assumed absolute magnitude of 7.80, amean albedo of 0.181, and an effective diameter of 86 km.
Figure 1. The lightcurve of 110 Lydia. The synodic period wasfound to be 10.924+0.003h with an amplitude of 0.14+0.01m.
196 Philomela
C.H.F. Peters discovered this asteroid in 1879 at Clinton. IRASV4.0 has estimated a diameter of 136 km for this object with anassumed absolute magnitude of 6.55. During three sessionsbetween November 16 and November 23, 2003, 559 images weretaken to derive a synodic period of 8.33+0.02h with an amplitudeof 0.10+0.02m. See Figure 2. During this time, the phase anglechanged from 8.6 to 6.3 degrees. The list of Minor PlanetLightcurve Parameters lists this object as having a period of8.343h, with various amplitudes between 0.07 and 0.37m.
Figure 2. The lightcurve of 196 Philomela. The synodic periodwas found to be 8.33+0.02h with an amplitude of 0.10+0.02m.
776 Berbericia
This object was discovered at Heidelburg by A. Massinger in1914. The synodic period was determined to be 7.67+0.04h withan amplitude of 0.26+0.01m. 386 images were taken in twosessions over a three-night span between November 24 andNovember 26, 2003. This asteroid is seen to have a somewhatunusual lightcurve with four maxima, although one of these isquite small. See Figure 3. Interestingly, it has roughly similarfeatures to the lightcurve of 110 Lydia, which also shows four
maxima. If and when their shapes are determined, it should beinteresting to see what form they take. The list of Minor PlanetLightcurve Parameters states this object as having a period of7.668h with amplitude estimates between 0.13m and 0.21m. Themean albedo is stated as 0.066 with an assumed absolutemagnitude of 7.68, yielding an effective diameter of 151 km,(IRAS V4.0).
Figure 3. The lightcurve for 776 Berbericia. The synodic periodwas determined to be 7.67+0.04h with an amplitude of0.26+0.01m.
804 Hispania
Hispania was discovered in 1915 at Barcelona by J. Comas Sola.The mean albedo is listed as 0.052 with an assumed absolutemagnitude of 7.84, yielding an effective diameter of 157 km,(IRAS V4.0). Ambiguity seems to have followed this objectthroughout the years of effort to determine its rotational lightcurveperiod. The list of Minor Planet Lightcurve Parameters shows aperiod of 14.840h, and an amplitude between 0.19 and 0.23m.However, examination of the references provided in the list showother determinations have been made in the area of 7.4h,Magnusson and Langerkvist (1991), Calabresi and Roselli (2001).
New lightcurve observations of Hispania were obtained fromDecember 9 to December 28, 2003, during which a total of 177images were taken during four sessions. My initial analysisshowed a synodic period of 7.462+0.015h with an amplitude of
Figure 4. The lightcurve for 804 Hispania. The synodic periodwas found to be 14.64+0.01h with an amplitude of 0.24+0.01m.
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0.20+0.02m. However, consultations with Robert Stevens ofSantana Observatory led me to revise the period upward to nearlydouble this. Using his much larger data set as a guide for analysis,I now derive a period of 14.64+0.01h with an amplitude of0.24+0.01m. However, there is a rather large hole in the curve, sothese parameters could well change somewhat with bettercoverage. The lightcurve is shown in Figure 4.
1825 Klare
This asteroid was discovered by K. Reinmuth at Heidelberg in1954. 438 images were taken between December 27, 2003 andJanuary 1, 2004, in five sessions. The measured synodic periodwas 4.744+0.009h with an amplitude of 0.75+0.02m. The largeamplitude would suggest a highly irregular shape. It was observedat phase angles varying from 6 to 3.5 degrees. The lightcurve ispresented in Figure 5.
Figure 5. The lightcurve for 1825 Klare. The measured synodicperiod was 4.744+0.009h with an amplitude of 0.75+0.02m.
Acknowledgments
Special thanks is given to Brian Warner for his continued help andsupport in my development in this area of research, and for hiscontinuing improvements to the program, “Canopus”. Thanks arealso given to Bob Stevens for his assistance with the solution ofthe 804 Hispania lightcurve.
References
Calabresi, M., and Roselli, G. (2001). “Research Note, TheRotation Period of 804 Hispania. Some Considerations on itsNature.” Astronomy and Astrophysics, 369, 305-307.
Harris, Alan W., and Warner, Brian D. (2003). “Minor PlanetLightcurve Parameters”, found on the Minor Planet Center website: http://cfa-www.harvard.edu/iau/lists/LightcurveDat.html.
IRAS V4.0 from NASA Small Bodies Node of the Planetary DataSystem, IRAS Minor Planet Survey V4.0. http://pdssbn.astro.umd.edu/nodehtml/sbdb.html
Magnusson, P., and Langerkvist, C. I. (1991). “Physical Studiesof Asteroids XXII. Photoelectric Photometry of Asteroids 34, 98,115, 174, 270, 389, 419 and 804.” Astronomy and AstrophysicsSupplement Series 87, 269-275.
Stevens, R. (2004). Private communications. http://home.earthlink.net/~rdstephens/default.htm
Warner, B.D. (2003). Collaborative Asteroid Lightcurve Link(CALL) web site. http://www.MinorPlanetObserver.com/astlc/default.htm.
LIGHTCURVE ANALYSIS FOR NUMBERED ASTEROIDS1351, 1589, 2778, 5076, 5892, AND 6386
The lightcurves of six numbered asteroids obtained in late2003 were analyzed. The following synodic periods andamplitudes were determined. 1351 Uzbekistania:73.90±0.02h, 0.34±0.02m; 1589 Fanatica: 2.58±0.05h,0.16±0.02m; 2778 Tangshan: 3.461±0.020h, 0.25±0.03m;5076 Lebedev-Kumach: 3.2190±0.0005h, 0.14±0.02m;(5892) 1981 YS1: 10.60±0.02h, 0.26±0.03m; and (6386)1989 NK1: 3.1381±0.0005h, 0.08±0.02m.
Equipment and Procedures
The asteroid lightcurve program at the Palmer Divide Observatoryhas been previously described in detail (Warner 2003) so only asummary is provided now. The main instrument at the
Observatory is a 0.5m f/8.1 Ritchey-Chretien telescope using aFinger Lakes Instruments IMG camera with Kodak KAF-1001Echip. A second instrument also in use was a 0.3m f/9.3 Schmidt-Cassegrain using an SBIG ST-9E camera. For this set of asteroids,only the 0.5m scope was used.
Initial targets are determined by referring to the list of lightcurvesmaintained by Dr. Alan Harris (Harris 2003), with additions madeby the author to include findings posted in subsequent issues ofthe Minor Planet Bulletin. In addition, reference is made to theCollaborative Asteroid Lightcurve Link (CALL) web sitemaintained by the author (http://www.MinorPlanetObserver.com/astlc/default.htm) where researchers can post their findingspending publication. MPO Canopus, a custom software packagewritten by the author, is used to measure the images. It usesaperture photometry with derived magnitudes determined bycalibrating images against field or, preferably, standard stars. Rawinstrumental magnitudes are used for period analysis, which isincluded in the program. The routine is a conversion of theoriginal FORTRAN code developed by Alan Harris (Harris et al.,1989).
Note: in the following, the orbital elements are taken from theIAU MPCORB data file available at the Minor Planet Center website (ftp://cfa-ftp.harvard.edu/pub/MPCORB/). The date ofosculation for the elements was 2453000.5.
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The Phase Angle Bisector
The observation table for each asteroid gives the date, phase angle,and phase angle bisector longitude and latitude. The PAB wasdeveloped by Alan Harris and Edward Bowell. Harris states(Harris 2003a), “The significance is that the direction that bisectsthe directions to the sun and the line of sight is a bestapproximation to a single ‘viewing direction.’ As an extremeexample, if you viewed a rotating ‘cigar’ from its pole it wouldhave no lightcurve amplitude if the sun were also shining from thepole direction, but if the sun were shining at the equator (90°phase angle), then you would see a big amplitude. Now if youreverse the Earth and sun positions so you are viewing from theequator and the sun is shining on the pole, you likewise get a bigamplitude, even though in this case the illuminated area isconstant, you just see different amounts of it as it rotates. The bestapproximation you can make to a zero phase angle viewing aspectis a single line half way in between the illumination and viewingdirections. This we call the ‘phase angle bisector’, since it is theline that bisects the phase angle.”
Results
1351 Uzbekistania
Uzbekistania was discovered by G.N. Neujmin at Simeis on 1934October 5. It’s carried the designations 1925 CA, 1928 QJ, 1931FK, 1934 TF, A917 SL, and A920 FA. It’s named in honor of the(former) Uzbek Soviet Republic where the discoverer lived duringWW II. Kozai (1979) puts the asteroid in his group 63, which
includes, among others, 48 Doris and 52 Europa. The IRASsurvey (Tedesco 1989) gives an effective diameter of 64.91 ±4.31km and mean albedo of 0.0606 ±0.0090. The IAUsMPCORB database gives values of 9.6 and 0.15 respectively for Hand G. The principal orbital elements for Uzbekistania are: semi-major axis, 3.197AU; inclination, 9.703°; and eccentricity, 0.0610.
There were 871 data points used in the final analysis that gave asynodic period of 73.90±0.02h and amplitude of 0.34±0.02m.Figure 1 shows the observations phased against this period. Theamplitude implies a ratio of 1.37:1 for the projected a/b axes of theassumed triaxial ellipsoid. The table below provides a summaryof the individual observation runs.
1589 Fanatica
M. Itzigsohn discovered 1589 Fanatica on 1950 September 13 atLa Plata. The name is in honor of Eva Peron whose devotion andenthusiasm for the people of Argentina led her to champion thecause of workers. The name literally means a fanatical woman orfeminine zealot. The asteroid has been designated 1935 RD, 1937CF, 1946 OE, 1950 RK, 1950 TM3, and A924 WC.
The H value from the MPCORB database 12.00. Using a formulaprovide by Harris (2003), which assumes the asteroid’s albedo(0.18) and type (S) based on the semi-major axis, the approximatediameter is 12 km. Kosai (1979) includes Fanatica in his group 15along with 11 Parthenope and 17 Thetis. The principal elementsare: semi-major axis, 2.417AU; inclination, 5.261°; andeccentricity, 0.0927.
Observations were obtained on three nights in late November andearly December, with a total of 261 data points used in the finalperiod analysis (see Figure 2). The synodic period was found tobe 2.58±0.05h and the amplitude to be 0.16±0.02m, or a projected
Figure 1. The lightcurve for 1351 Uzbekistania. The synodicperiod is 73.9±0.02h and the amplitude 0.34±0.02m.
Figure 2. The lightcurve for 1589 Fanatica phased against asynodic period of 2.58±0.05h. The amplitude is 0.16±0.02m.
DATE Phase PAB2003 Angle Long LatNov. 29 7.9 52.7 –4.1Nov. 30 8.4 52.8 –4.0Dec. 01 8.9 52.8 -4.0
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a/b ratio of 1.16:1 for the assumed triaxial ellipsoid. The tablebelow provides a summary of the individual observation runs.
2778 Tangshan
Tangshan is named for a city in the Hebei province in northernChina. It was discovered at the Purple Mountain Observatory atNanking on 1979 December 14. Its last designation was 1979 XPwith its earliest designation being 1948 WL. Using the formula byHarris (2003), the approximate diameter is 8 km when using theMPCORB H value of 13.00 and albedo of 0.18. The principalelements are: semi-major axis, 2.281AU; inclination, 4.616°; andeccentricity 0.1212.
Figure 3 shows the 265 data points obtained on Nov. 26 and Nov.28, 2003, that were used in the final period analysis. The synodicperiod of the lightcurve is 3.461±0.020h and its amplitude is0.25±0.03m, which yields a projected a/b axis ratio of 1.26:1 forthe assumed triaxial ellipsoid. The table below provides asummary of the individual observation runs.
Figure 3. The lightcurve for 2778 Tangshan. The data is phasedagainst a synodic period of 3.461±0.020h. The amplitude is0.25±0.03m.
DATE Phase PAB2003 Angle Long LatNov. 26 2.5 61.1 –3.4Nov. 28 3.3 61.2 –3.3
5076 Lebedev-Kumach
Discovered by L. I. Chernykh on 1973 September 26 at Nauchnyj,Lebedev-Kumach is named for Vasilij Ivanovich Lebedev-Kumach (1898-1949), prominent poet and song-writer, known forhis lyrical and patriotic verses for songs for many Soviet films.The principal elements are: semi-major axis, 2.416AU;inclination, 9.481°; and eccentricity 0.2327. Assuming an albedoof 0.18 per Harris (2003) and the H value of 13.00 from theMPCORB data file, the approximate diameter is 8 km.
Observations were obtained in October and November 2003, with150 data points used in the final period analysis. The synodicperiod of the lightcurve was found to be 3.2190±0.0005h and the
amplitude to be 0.14±0.02m. Assuming a triaxial ellipsoid, theamplitude gives a ratio of 1.14:1 for the projected a/b axes. Figure4 shows a phased plot against this period. The table belowprovides a summary of the individual observation runs.
Figure 4. The lightcurve for 5076 Lebedev-Kumach. The synodicperiod is 3.2190±0.0005h with an amplitude of 0.14±0.02m.
DATE Phase PAB2003 Angle Long LatOct. 05 6.2 2.3 1.1Nov. 15 25.8 8.8 –2.7Nov. 25 28.3 11.6 –3.5
Figure 5. A phased lightcurve for (5892) 1981 YS1 using asynodic period of 10.60±0.02h. The amplitude is 0.26±0.03m.
This is another discovery from Purple Mountain Observatory atNanking (1981 December 23). The asteroid has also carried thedesignations 1971 BS1, 1988 QG1, and 1988 UZ. Again using theformula from Harris (2003) and assumed albedo of 0.18, the Hvalue of 13.60 gives an approximate diameter of 6 km. Theprincipal elements are: semi-major axis, 2.384AU; inclination,4.585°; and eccentricity 0.3020.
358 observations obtained on four nights in December 2003 wereused to find a synodic period for the lightcurve of 10.60±0.02hand amplitude of 0.26±0.03m. The latter implies a ratio of 1.27:1for the projected a/b axes of a triaxial ellipsoid. Figure 5 shows aphased plot of the observations and the table below gives asummary for each run.
(6386) 1989 NK1
H.E. Holt discovered 1989 NK1 on 1989 July 10 at Palomar. Ithas also been designated 1955 RG1 and 1991 FW4. Assuming analbedo of 0.18, based on Harris (2003), and using the H value of12.70 from the MPCORB table, the approximate diameter is 9 km.The principal elements are: semi-major axis, 2.271AU;inclination, 8.737°; and eccentricity 0.3008.
Observations were made in October and November 2003. The211 data points used for analysis are shown in Figure 6 against thederived synodic period of 3.1381±0.0005h. The amplitude of thecurve is 0.08±0.02m. This would give a ratio of 1.08:1 for theprojected a/b axes of a triaxial ellipsoid. The table below providesthe viewing aspects for each of the observation runs.
Figure 6. A phased lightcurve for (6386) 1989 NK1 using asynodic period of 3.1381±0.0005h. The amplitude is 0.08±0.02m.
Thanks go to Dr. Alan Harris of the Space Science Institute formaking available the source code to his Fourier Analysis programand his continuing support and advice. I also thank Robert D.Stephens of Santana Observatory, Rancho Cucamonga, for his on-going advice and support.
References
References Note: Asteroid names and discovery information arefrom Schmadel (1999).
Harris, A.W., Young, J.W., Bowell, E., Martin, L.J., Millis, R.L.,Poutanen, M., Scaltriti, F., Zappala, V., Schober, H.J., Debehogne,H., and Zeigler, K.W., (1989). “Photoelectric Observations ofAsteroids 3, 24, 60, 261, and 863.” Icarus 77, 171-186.
Harris, Alan W. (2003). “Minor Planet Lightcurve Parameters.On Minor Planet Center web si te: http:/ /cfa-www.harvard.edu/iau/lists/LightcurveDat.html
Harris, Alan W. (2003a). Private communications.
Kozai, Y., (1979). “The dynamical evolution of the Hirayamafamily.” In Asteroids (T. Geherels, Ed.) pp. 334-358. Univ. ofArizona Press, Tucson.
Schmadel, L. (1999). Dictionary of Minor Planet Names, 4thedition. Springer-Verlag, Heidelberg, Germany.
Tedesco, E. F., Tholen, D.J., and Zellner, B. (1989). “UBV colorsand IRAS alebedos and diameters”. In Asteroids II (R.P. Binzel,T. Gehrels, and M.S. Matthews, Eds.), pp. 1090-1138. Univ. ofArizona Press, Tucson.
Warner, B. D. (2003), “Lightcurve Analysis for [Several]Asteroids”, Minor Planet Bulletin 30, 21-24.
CALL FOR OBSERVATIONS
Frederick PilcherIllinois College
Jacksonville, IL 62650 USA
Observers who have made visual or photographic measurementsof positions of minor planets in calendar 2003 are encouraged toreport them to this author on or before April 1, 2004. This will bethe deadline for receipt of reports which can be included in the“General Report of Position Observations for 2003,” to bepublished in MPB Vol. 31, No. 3.
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Minor Planet Bulletin 31 (2004)
PHOTOMETRY OF 804 HISPANIA, 899 JOKASTE,1306 SCYTHIA, AND 2074 SHOEMAKER
Results for the following asteroids (lightcurve periodand amplitude) observed from Santana Observatoryduring the period September to December 2003 arereported: 804 Hispania (14.845 ± 0.01 hours and 0.21mag.), 899 Jokaste (6.245 ± 0.005 hours and 0.28 mag.),1306 Scythia (15.05 ± 0.01 hours and 0.18 mag.), 2074Shoemaker (57.02 ± 0.1 hours and 0.45 mag.).
Santana Observatory (MPC Code 646) is located in RanchoCucamonga, California at an elevation of 400 meters and isoperated by Robert D. Stephens. Details of the equipment andreduction techniques are found in Stephens (2003) and at theauthor’s web site (http://home.earthlink.net/~rdstephens/default.htm). All of the asteroids were selected from the “CALL”web site “List of Potential Lightcurve Targets” (Warner 2003).Shoemaker was selected because it is a Hungaria asteroid andbecause it is named in honor of Eugene Shoemaker.
804 Hispania
Discovered March 20, 1915 by J. Comas Solá at Barcelona,Hispania is a main-belt asteroid. Hispania is the Latin name ofSpain. Seven hundred sixty nine observations over five sessionsbetween October 7 and 13, 2003 were used to derive the synodicrotational period of 14.845 ± 0.01 hours with an amplitude of0.21 ± 0.02 magnitude. Table I gives the phase angles during theobserving run.
Figure 1: Lightcurve of 804 Hispania based upon a derived periodof 14.845 ± 0.01 hours. Zero phase is J.D. 2452920.867512(corrected for light-time).
899 Jokaste is a main-belt asteroid discovered August 3, 1918 byM. Wolf at Heidelberg. It is probably named for a figure in theopera Die Fledermaus by Johann Strauss. Three hundred oneobservations over three sessions between November 27 andDecember 3, 2003 were used to derive the synodic rotationalperiod of 6.245 ± 0.005 hours with an amplitude of 0.28 ± 0.02magnitude. Table II gives the observed range of phase angles.
Figure 2: Lightcurve of 899 Jokaste based upon a derived periodof 6.245 ± 0.005 hours. Zero phase equals J.D. 2452975.801180(corrected for light-time).
Discovered July 22, 1930 by G. N. Neuymin at Simeïs, Scthia is amain-belt asteroid. It is named for the country of the ancientScythians, comprising parts of Europe and Asia in regions northof the Black sea and east of the Aral Sea. Its estimated size is 34km in diameter. Three hundred eighty four observations overfour sessions between September 23 and 30, 2003 were used toderive the synodic rotational period of 15.05 ± 0.01 hours with anamplitude of 0.18 ± 0.03 magnitude. Table III gives the phaseangles during the observing run.
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Minor Planet Bulletin 31 (2004)
Figure 3: Lightcurve of 1306 Scythia based upon a derivedperiod of 15.05 ± 0.01 hours. Zero phase equals J.D.2452908.860012 (corrected for light-time).
Table III: Observing circumstances for 1306 Scythia
2074 Shoemaker
2074 Shoemaker is a Hungaria asteroid discovered by E. Helin atPalomar on October 17, 1974. It is named in honor of EugeneShoemaker (1928-1997). Based upon its H value, Shoemaker isestimated to be between 4 and 9 km in size. Seven hundredtwenty two observations over nine nights between October 15 andNovember 3, 2003 were used to derive the synodic rotationalperiod of 57.02 ± 0.10 hours with an amplitude of 0.45 ± 0.03magnitude. Its long period made it very difficult to get adequateoverlap between the sessions. Each session contributed barely 10percent to the lightcurve. Finally, the California wildfires, whichburned to within a half a kilometer of the observatory curtailedobservations until the asteroid was too low to observe. Becausethe asteroid was moving so fast, each night had to be split intotwo sessions with different comparison stars which werecorrected with zero point adjustments. Table IV gives the phaseangles during the observing run.
Figure 4: Lightcurve of 2074 Shoemaker based upon a derivedperiod of 57.02 ± 0.10 hours. Zero phase equals J.D.2452929.762632 (corrected for light-time).
Table IV: Observing circumstances for 2074 Shoemaker
Acknowledgements
Many thanks to Brian Warner for his continuing work andenhancements to the software program “Canopus” which makes itpossible for amateur astronomers to analyze and collaborate onasteroid rotational period projects and for maintaining the CALLWeb site which helps coordinate collaborative projects betweenamateur astronomers.
References
Stephens, R. D. (2003). “Photometry of 2134 Dennispalm, 2258Viipuri, 3678 Mongmanwai, 4024 Ronan, and 6354 Vangelis.”MPB 30, 46-48.
Stephens, R. D. (2003).http://home.earthlink.net/~rdstephens/default.htm.
Warner, B. (2003). “Potential Lightcurve Targets.”http://www.minorplanetobserver.com/astlc.targets.
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Minor Planet Bulletin 31 (2004)
CCD PHOTOMETRY OF 1248 JUGURTHA
Walter E. WormanDepartment of Physics and AstronomyMinnesota State University Moorhead
Moorhead, MN 56563
Michael P. OlsonDepartment of Physics
North Dakota State UniversityFargo, ND 58105
(Received: 8 December Revised: 11 January)
CCD observations were made of 1248 Jugurtha on fournights in February and March 2002. The synodic periodof rotation was found to be 12.190 ± 0.002 hours withthe lightcurve amplitude evolving from 0.827 ± 0.017 to0.734 ± 0.017 magnitudes. The period and largeamplitude are in agreement with previously reportedvalues.
Observations
The asteroid 1248 Jugurtha is a main-belt asteroid with semi-major axis of 2.72 AU. Koff and Gross (2002) previouslyreported a period of 12.1897 ±0.0001 hours with an amplitude inexcess of 0.70 magnitudes. The new observations of 1248Jugurtha we report here were made at the Paul Feder Observatory,located on the Buffalo River Site of the Minnesota StateUniversity Moorhead Regional Science Center. Data werecollected on the nights of February 17, 21, 22, and March 10,2002.
The observatory has a 16-inch computer controlled Cassegraintelescope made by DFM. The associated Photometrics Star 1CCD camera system was used to collect data. In all, 147 imageswere made of the asteroid during the four nights. Of these, 141were used in the analysis. The others were rejected because theasteroid image was too close to another star or to dawn. Theexposures were 3 minutes long and typically separated by 10minutes. No filter was used. Dark current and flat fieldcorrections were made to the data. Three stars were used asmagnitude standards for each image. The magnitudes were takenfrom the Guide 7 program (Hubble Guide Star Catalog). A leastsquares fit was done for each image and the relation between themagnitude and the log of the total count determined. Themagnitude of the asteroid was then determined from thisrelationship. A photometric aperture of 11 pixels by 11 pixels wasused and an equal sized region of the background nearby was usedfor the background correction.
Results
Times were corrected for travel time from the asteroid to the Earthand were taken to be at the mid-times for the images. Lightcurveswere made for each of the four nights. Relative magnitudes fromnight to night were uncertain as different comparison stars wereused. This was dealt with by using additive constants for thesecond, third and fourth night magnitudes to bring them intoagreement with the first night. A single lightcurve for the fournights was then least squares fit to a Fourier series including nineharmonics. The additive constants for the second through fourthnights and the period were then adjusted so that the fit minimized
the sum of the squares of the residuals. The resulting values werea period of 12.190 ± 0.002 hours, the additive constant for thesecond night was –0.0875, for the third night was –0.4719, and forthe fourth night was 0.3297 magnitudes. These are reasonable asthe uncertainties in the Hubble Guide Star Catalog are given to beabout ± 0.4 magnitudes. The standard deviation of the residualswas 0.017 magnitudes, which is due to the amplitude difference ofthe last night compared to the previous three.
A period of 12.190 hours was assumed and the second throughfourth night data were translated to fall on the first night data togive the composite lightcurve shown in Figure 1. The time scaleis given in rotational phase with the zero corresponding to 0 hr onFebruary 17, 2002 UT. There are clearly two maxima and twominima per rotation. The amplitude of the lightcurve is 0.827 ±0.017 magnitudes for the first day and 0.734 ± 0.017 magnitudesfor the last day. The phase angle during the first three days ofobservations varied between 8.9° and 7.3°, and the last day was5.4°. We believe that this phase angle change is responsible forthe amplitude trend as less shadowing occurs on the asteroid atsmaller phase angles.
Reference
Koff, R.A. and Gross, J. (2002). “Lightcurve Photometry ofAsteroid 1248 Jugurtha.” MPB 29, 75-76
Figure 1. Rotational lightcurve for 1248 Jugurtha assuming aperiod of 12.190 hours. The V magnitude scale is approximateowing to the typical 0.4 mag. uncertainty of the Hubble Guide StarCatalog.
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Minor Planet Bulletin 31 (2004)
THE MINOR PLANET OBSERVER:MAKING AND READING HISTORY
The news came in mid-October, 2003: the long lost minor planet1937 UB, also known as Hermes, had been recovered. Brian Skiffof the Lowell Observatory Near-Earth-Object Search (LONEOS)program made the observations that sent astronomers, professionaland amateur, scurrying to their instruments. Within a few days,radar and optical observations confirmed that the asteroid wasactually two separate bodies rotating around one another. You canread more about the recovery at http://www.lowell.edu/press_room/releases/recent_releases/Hermes_rls.html.
As often happens with the announcement of an NEO discovery orrecovery, there was a rush to gather as much data as possible. Insome cases, that amounted to “overkill” as the Minor PlanetCenter received 50 or more astrometric observations a night in thedays immediately following recovery. That’s not meant todiscourage or disparage those who did turn in the observations.Only to note that one wishes there could be such interest moreoften, even when the targets are more mundane.
I was one of those who jumped into the rush to get opticallightcurve data to support findings being reported by radarimaging teams. Two teams of optical observers took the fore onacquiring the data and analyzing it. One was lead by Petr Pravecat Ondrejov Observatory, of which I was a part, and RaoulBehrend of Geneva Observatory headed the other. A total ofabout 15 observers from Europe, Australia, and the U.S.contributed data that eventually lead to the finding of an orbitalperiod for the pair of about 13.9h with an amplitude of 0.07m.The analysis further indicated that the objects appear to be lockedin synchronous rotation. It never ceases to amaze me that one canmake such determinations for asteroids based simply on thechanging brightness over time. The feat becomes even moreamazing when applied to eclipsing binary stars, which I’ve donewith the aid of the program, Binary Maker by David Bradstreet.
What the episode demonstrates is the value of cooperation andcollaboration among professionals and among professionals andamateurs. Hermes was a difficult target, not so much because ofits brightness or motion across the sky but because of the lowamplitude of the curve and the uncertainty of the initial results.This was one time where overwhelming the problem with datawas not a waste of time and effort but a strong necessity.
Most readers of these pages don’t need to be told that pro-amcollaborations can lead to a number of important discoveries andcontinued advancement in many aspects of astronomy. There arealready many such collaborations among those involved inasteroids and eclipsing binary stars. Those collaborations havehelped lead to some important developments in recent years andwill continue to do so. There are many amateurs available whocan and do high-level work every day (or night). The problem isgetting them tied up with professionals who can do the criticalanalysis if they have the data.
Addressing this problem is just one goal of the Society forAstronomical Sciences, formerly the IAPPP-West, which holds an
annual meeting in Big Bear, CA, each year. The group changedits name in 2003 and is working towards developing a method andprocess – a network, if you will – to build a pool of high qualityobservers and give professionals access to that pool. This parallelsthe work that has long be done by the American Association ofVariable Star Observers (AAVSO) with whom SAS is trying towork along with other groups. If you’d like more information onSAS, visit their home page at http://www.socastrosci.org.
One of the pleasures I had while out working on Hermes and otherasteroids late in 2003 was to see a spectacular aurora. It’s rare tosee much, if anything, from my mid-latitude location in Coloradobut the heightened solar activity resulted in some spectacularshows of bright green curtains, blood red sheets, rays of all lengthsand colors seen by those as far south as the southern tier of theUnited States. Of course, one man’s treasure is another man’sjunk. Some Canadian amateurs were quick to point out that whilethe show was nice, they see such displays quite often with manyso bright that the sky becomes is as if the quarter moon or morewas present. This brought to mind a time when I was doing somevisual variable star estimates and couldn’t figure out why the faintvariable suddenly disappeared. I looked up to see almost theentire sky filled with sheet upon sheet of bright red aurora. I maymarvel at such a display now, but I’ll also wonder if a fewhundred miles north some other amateur is cursing Mother Nature.
I’ve been reading a very well done book called “Galileo’sDaughter” by Dava Sobel (ISBN 0-8027-1343-2). It’s not new,having been published in 1999, but if you haven’t had a chance toread it, I recommend it very highly. It’s a tremendous andtouching insight into Galileo’s writings and times using in partsome or all of the 124 letters written by one of two of hisdaughters, both of whom he placed in a convent before theirsixteenth birthday. It’s an unfortunate part of history that hisletters to her did not survive. The mother abbess of the conventdestroyed them soon after Suor Maria Celeste’s death in fear ofreprisals from the Church for having the materials of a declaredheretic.
I also managed to read – finally – Donald Yeoman’s book oncomets. This time I was about two decades behind the times. Ithink what started the reading frenzy was getting bogged down inthe technical side of observing. It’s been a nice diversion to learna little more about the history and people in astronomy. It alsomeant renewing a library card that was so old and infrequentlyused that the library district didn’t think I was still alive. I wasglad to report such was the case and have rediscovered the joy ofjust wandering through the library during my lunch hour fromtime to time. There’s something old and something new aroundevery corner just waiting to be discovered.
With northern summer rapidly approaching, and so the asteroidsdipping well south of the celestial equator, I’ll be taking more timeto read some history, and traveling to one or more meetings. Iparticularly look forward to the latter as it gives me a chance tomeet with some of you and learn how to improve my observingand data analysis skills. I hope to see some new faces and helpdevelop new cooperative efforts among professionals andamateurs. Let there be no doubt: the day of the amateur is farfrom over despite the new large scopes and surveys coming online. Clear Skies!
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Minor Planet Bulletin 31 (2004)
LIGHTCURVES AND ROTATIONAL PERIODS OF1474 BEIRA, 1309 HYPERBOREA, AND 2525 O'STEEN
Gordana ApostolovskaInstitute of Physics, Faculty of Natural Sciences
The V-band lightcurves of the asteroids 1474 Beira,1309 Hyperborea, 2525 O'Steen, and the mean colorindices for 1474 Beira are presented. The CCDobservations were carried out at the Bulgarian NationalAstronomical Observatory Rozhen (MPC Code 071).The calculated synodic periods are: 1474 Beira,4.184±0.002h; 1309 Hyperborea, 13.95±0.02h; and2525 O'Steen, 3.55±0.01h.
The observations we report for 1309 Hyperborea, 1474 Beira, and2525 O'Steen were made at the Bulgarian National AstronomicalObservatory Rozhen (MPC Code 071). The data for Beira andO'Steen were obtained with an SBIG ST-8E (Kodak KAF-1602E,1536x1024px2, 1px=9µ m) CCD camera attached to a0.50m/0.70m Schmidt telescope. A Photometrics CCD camera(CE200A-SITe, 1024x1024, 1px=24µm) was used with the 2-mRCC for observing of Hyperborea. Until our choice of theseobjects, there was no reported information for photometricobservations of these asteroids in the list of Harris (2003).
In the preliminary reduction, images were dark and flat fieldsubtracted. The flat field correction with precision <1% was madeusing twilight and dawn sky flat fields. The V-band lightcurveswere derived from the differential magnitudes between theasteroid and comparison stars. Aperture photometry wasperformed using the software program CCDPHOT (Buie, 1998).For lightcurve analysis, we used Asteroid Catalog Software (APC)(Magnuson et al. 1990), that produces composite lightcurves,calculates rotational periods, and provides the Fourier analysisfitting procedure of the lightcurve, which we used.
1474 Beira
Beira is a Mars-crossing asteroid with a semi-major axis of 2.74AU, eccentricity 0.49 and inclination of orbit 26.7 degrees. Beirawas discovered in 1935 by C. Jackson in Johannesburg. Theassumed diameter of Beira in the IRAS Minor Planet Survey,(Tedesco, 1992) is 39 km. The Tholen taxonomic type (Tholen,1989) is FX. At the time of observation asteroid was at 14.6m andthe solar phase angle was 31.5 degrees. On 24 and 25 of August2003, Beira was observed for about 6 hours, an interval that wasmore than the full lightcurve coverage. We determined thesynodic period to be 4.184±0.002 hours. The amplitude of thecomposite lightcurve, Fourier fitted of order 6, is 0.149±0.010magnitude. The obtained composite lightcurve has maxima andminima which slightly differ from each other by shape and height.
On 21 September 2003, three days before Beira's particularlyfavorable opposition, the asteroid was observed in B, V, R and Ibands. All frames were taken through a standard Johnson-Cousinsset of filters. The reduction to the BVRI standard system of theasteroid magnitudes was made by means of the observations oftwo standards fields SA114 and PG0231+051 (Landolt, 1992).The atmospheric extinctions were kB=0.32±0.03, kV=0.15±0.02,kR=0.140±0.036 and kI=0.07±0.01. The mean values of the colorindices of the asteroid were measured as: B-V=0.70±0.049,V-I=0.687±0.012, R-I=0.314±0.006, and V-R=0.378±0.025.
Figure 1: Lightcurve of 1474 Beira based on a period of4.184±0.002 hours.
Figure 2: Lightcurve of 1309 Hyperborea based on a period of13.95±0.014 hours.
(1309) Hyperborea
Hyperborea is a main-belt asteroid discovered in 1931 by G. N.Neujmin in Simeis. It has a semi-major axis of 3.20 AU,eccentricity 0.15 and inclination of orbit 10.28 degrees. Thediameter of Hyperborea is 59 km (Tedesco, 1992). Theobservations of this asteroid at Rozhen were carried out in twonights: 12 and 14 January 2002. On the first night, bad weatherconditions permitted only 2 hours of observations. The secondnight of observations cover 7.5 hours of the lightcurve, whichreveals a nice maximum and very sharp minimum. Assuming astandard lightcurve with two pairs of symmetrical extrema weestimate a period of 13.95±0.02 hours. The amplitude of the
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Minor Planet Bulletin 31 (2004)
composite lightcurve for the presented phase interval is about 0.4magnitude.
(2525) O'Steen
This asteroid was discovered in 1981 by B. A. Skiff in Flagstaff atthe Anderson Mesa Station. O'Steen is a main-belt asteroid with asemi-major axis of 3.13 AU, eccentricity 0.195 and inclination oforbit 2.78 degrees. The assumed diameter of 2525 O’Steen is 106km (Tedesco, 1992). O'Steen was observed on 23 of September2003. In the time of the observation the asteroid was 14m and thesolar phase angle was 6.98 degrees. One night observations with aduration of 6 hours covered more than one cycle of the asteroid.The composite lightcurve based on a synodic period of 3.55±0.01hours is asymmetric. The amplitude of the composite lightcurve,Fourier fitted of order 4, is 0.193±0.009 magnitude.
Figure 3: Lightcurve of 2525 O'Steen based on a period of 3.55±0.01 hours. The Fourier fit of order 4 is presented with solid line.
Acknowledgments
This research was supported by contract Num, NZ-904/99 with theNational Science Fund, Ministry of Education and Sciences,Bulgaria and by contract with the Ministry of Education andScience, Republic of Macedonia.
References
Buie, M. W., (1998). http://www.lowell.edu/users/buie/idl/ccdphot.html
Harris, A. W. (2003). “Minor Planet Lightcurve Parameters”. Onthe Minor Planet Center website: http://cfa-www.harvard.edu/iau/lists/LightcurveDat.html (updated October 2003)
Landolt, A.U., (1992). “UBVRI Photometric standard stars in themagnitude range 11.5<V<16.0 around the celestial equator”.Astron. J. 104, 340-491
Magnuson , P. and Lagerkvist, C. I., (1990). “Analyses ofasteroid lightcurves. I. database and basic reduction.” Astron.Astrophys. Suppl. Ser. 86, 45-51
Tedesco, E., F. (Ed.), 1992. IRAS Minor Planet Survey, (PhillipsLaboratory Technical Report No. PL-TR-92-2049. Hanscom AirForce Base, MA)
Tholen, D. J., (1989). “ Asteroid taxonomic classifications.” InAsteroids II (R. P. Binzel, T. Gehrels, and M. S. Matthews, Eds.),pp 1139-1150. Univ. Arizona Press, Tucson.
BOOK REVIEW
Richard P. Binzel, Editor
A Practical Guide to Lightcurve Photometry andAnalysis by Brian D. Warner. Bdw Publishing, 2003.ISBN 0-9743849-0-9, paperback, 266 pages. (Price$30, available at www.MinorPlanetObserver.com)
Oh how long we have waited for a book like this! In the distantpast, amateurs had to crack their way into the field of lightcurvephotometry by tackling papers such as Hardie (1959) and bybuilding their own photometers following the classic book byFrank Bradshaw Wood (1963). Several follow-on books thatcarried the field forward were published by Willmann-Bell, Inc.,including Genet (1983) and Henden and Kaitchuck (1990). Theaffordability, proliferation, and enabling capabilities of CCDcameras at “amateur” observatories has opened a huge potentialfor new opportunities for new observers to make valuablelightcurve photometry measurements. Yet a void has existed indetailing how to get started and carry forward a program oflightcurve photometry driven by scientific curiousity.
Brian D. Warner’s Practical Guide now fills that void. It iswritten from the perspective of one who still remembers what itwas like to start as a beginner. Thus the writing comes across in awarm and welcoming style. Much advice comes from Warner’sown experience, building upon works like Henden and Kaitchuck(1990), and it is conveyed as being told from one friend toanother. It is hard to imagine any new person who picks up thisbook with genuine interest being able to resist taking the author’sextended hand and gently being guided forward. Warner firstcoaxes his readers to take the plunge by tantalizing them with thescience that comes out of the observations. Those who try CCDlightcurve photometry because of the technical challenge will do itonce or twice and then move to the next challenge elsewhere.This book’s approach is to capture you for the long term bygetting you hooked on the joy and satisfaction of learning andcontributing new scientific knowledge about our Universe. It isthis common passion for new knowledge that erases barriersbetween “amateur” and professional astronomers. There are nobarriers here.
About 40 pages of the book are devoted to communicating thefundamentals of photometry, and this is accomplished with theclear and concise skill of a patient and expert teacher. Manyreferences here (and in the book’s Bibliography) tell you where togo for more depth than this overview allows. Technical terms aregiven in italics when first introduced and a nice (although limitedin length) Glossary is given at the end for additional help.Throughout the book, text blocks are offset within boxesdisplaying the subheading “Tying It Together…” to try to keep thebig picture in mind while focusing on the details. Becausecomputers and software are so intertwined with CCD datacollection and reduction, the bulk of this book provides a guide tohow to use these tools. While Warner himself has developed awide variety of excellent and popular software tools, he does notexclusively tout his own packages. Most importantly, the author
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Minor Planet Bulletin 31 (2004)
tries to convey an understanding of what the various reductionsteps are intended to accomplish. Numerous correct and fullywarranted cautionary statements are made not to place blind trustin the output of these packages, but to give careful human thoughtas to whether the results being spit out make sense. The copiousexamples serve to help a beginner to learn rapidly many of themost common pitfalls. Ultimately it is the experience that the newobserver gains with her/his own data that brings about confidenceand expertise.
New observers who are ready to start their own programs will findadvice on how to get off the ground and choose targets to beginworking on. Recognizing that the higher purpose is tocommunicate one’s results, one of the final sections of the bookdescribes the task and venues for publication, including the MinorPlanet Bulletin. Many details and technical examples are savedfor the Appendices, making the main body of the text smoothlyflowing and readable. Finally the inclusion of standard star fields,reprinted with permission, puts some enormously useful referencematerial into a single accessible place. The quality and clarity ofthe printing of the standard star charts enables excellentphotocopies of these pages – for personal use and handling ease atthe telescope or computer screen.
Brian D. Warner’s Practical Guide is an instant classic andrequired reading for anyone learning the ropes of CCD photometryand its application to the challenge of lightcurve observations ofboth asteroids and variable stars. More than any other volume inthe past decade, this book will spark new interest and newobservers to the field of lightcurve studies. Thank you Brian forilluminating the way. We welcome all who follow.
References
Genet, R. M. (1983). Solar System Photometry Handbook.Willmann-Bell, Inc., Richmond, VA.
Hardie, R. H. (1959). “An Improved Method for MeasuringExtinction.” Astrophys. J. 130, 663-669.
Henden, A. and Kaitchuck, R. (1990). Astronomical Photometry.Willmann-Bell, Inc., Richmond, VA.
Wood, F. B. (1963). Photoelectric Astronomy for Amateurs.Macmillan, New York.
LIGHTCURVE PHOTOMETRY OPPORTUNITIESAPRIL – JUNE 2004
Brian D. WarnerPalmer Divide Observatory
17995 Bakers Farm Rd.Colorado Springs, CO 80908
Mikko KaasalainenRolf Nevanlinna Institute
P.O. Box 4 (Yliopistonkatu 5, room 714)FIN-00014 University of Helsinki
Finland
Alan W. HarrisSpace Science Institute
4603 Orange Knoll Ave.La Canada, CA 91011-3364
Petr PravecAstronomical InstituteCZ-25165 Ondrejov
Spinning “flat hamburgers”, “potatoes”, and “footballs” are oftenused to describe an asteroid when explaining its lightcurve. Eventhe human head can give a reasonable approximation to somelightcurves – assuming the person is not bald! The point is thatasteroids come in all sorts of shapes and sizes and that it’sbecoming increasingly important to determine the shapes andorientation of the spin axis for as many asteroids as possible.
A recent review of the known lightcurves and spin axes shows analmost certain influence of the YORP effect on the spin rates andorientations of asteroids less than about 40km in size. The exactshape, or good approximation, of the asteroid is important sincethe influence of the YORP effect is most powerful when the objectis highly irregular in shape.
For many years, the thrust of this article has been to getlightcurves on any object since the number of well-establishedlightcurve parameters was woefully small. The list of spin axisvalues was nearly non-existent. In recent years, there has been adramatic increase in the number of entries on both lists, which arejust now beginning to tell part of the tale of the true evolution ofthe asteroid system. This is no time to rest on our laurels but, withthe promise of even more exciting and important discoveries to bemade for the want of more observations, to reinforce ourdetermination. Again, let there be no doubt that observations willbe put to use. The fear that they will be lost in the dark chasms oftime and neglect should be put aside.
So that neither goal – more raw lightcurves and curves forshape/axis studies – is neglected, we’re including two lists. Thefirst contains asteroids that have no or poorly establishedparameters. Note that this time around we’ve included a numberwith at least preliminary values, some with very long periods.These are challenging, no doubt, but no less important than apassing NEO spinning several times an hour. In fact, they may bemore important right now since the slow rotators are, for a largepart, the greatest mystery in the study of spin rates.
The second list should be of help for those with smallerinstruments. They are relatively bright and so should be withineasy reach. These objects are only a small number of well donelightcurves away from having their shape and/or spin axisresolved, or at least reasonably known. Those working objects onthis list should contact co-author Mikko Kaasalainen to coordinatetheir efforts with his and to be sure that the object has not sincebeen observed well enough to have been modeled.
Important Notes: 1) The periods that are listed should beconsidered preliminary. Don’t be overly influenced by them andtry to force your results to the same or similar values. Let the datadictate the solution, not vice versa. 2) The Declination is actuallyfor when the asteroid is brightest. In most cases, it is about thesame for when at opposition.
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Minor Planet Bulletin 31 (2004)
You’ll find a more complete list of lightcurve opportunities for thecurrent and recent quarters on the CALL web site.(http://www.MinorPlanetObserver.com/astlc/default.htm). Besure to check the link on the CALL site to planned radarobservations. Optical observations are often needed to support theradar work.
The Minor Planet Bulletin is open to papers on all aspects ofminor planet study. Theoretical, observational, historical, review,and other topics from amateur and professional astronomers arewelcome. The level of presentation should be such as to bereadily understood by most amateur astronomers. The preferredlanguage is English. All observational and theoretical papers willbe reviewed by another researcher in the field prior to publicationto insure that results are presented clearly and concisely. It ishoped that papers will be published within three months of receipt.However, material submitted by the posted deadline for an issuemay or may not appear in that issue, depending on available spaceand editorial processing.
The MPB will not generally publish articles on instrumentation.Persons interested in details of CCD instrumentation should jointhe International Amateur-Professional Photoelectric Photometry(IAPPP) and subscribe to their journal. Write to: Dr. Arnold M.Heiser, Dyer Observatory, 1000 Oman Drive, Brentwood, TN37027 (email: [email protected]). The MPB willcarry only limited information on asteroid occultations becausedetailed information on observing these events is given in theOccultation Newsletter published by the International OccultationTiming Association (IOTA). Persons interested in subscribing tothis newsletter should write to: Art Lucas. Secretary & Treasurer,5403 Bluebird Trail, Stillwater, OK 74074 USA([email protected]). Astrometry measurements should besubmitted to the IAU Minor Planet Center and are no longer beingpublished or reproduced in the MPB.
Manuscript Preparation
It is strongly preferred that all manuscripts be prepared using thetemplate found at: http://www.minorplanetobserver.com/astlc/default.htm Manuscripts should be less than 1000 words. Longermanuscripts may be returned for revision or delayed pendingavailable space. For authors not using the template noted above,manuscripts may be submitted electronically as ASCII text or onpaper as a typescript. Typescripts should be typed double spacedand consist of the following: a title page giving the names andaddresses of all authors (editorial correspondence will beconducted with the first author unless otherwise noted), a briefabstract not exceeding four sentences, the text of the paper,acknowledgments, references, tables, figure captions, and figures.Please compile your manuscripts in this order.
For lightcurve articles, authors are encouraged to combine asmany objects together in a single article as possible. For generalarticles, the number of tables plus figures should not exceed two.Tables should be numbered consecutively in Roman numerals,figures in Arabic numerals. We will typeset short tables, ifnecessary. Longer tables must be submitted in “camera ready”format, suitable for direct publication. Font size should be largeenough to allow for clear reproduction within the columndimensions described below. We prefer to receive figures inelectronic format, 300 dpi or higher quality, black markings onwhite. Because of their high reproduction cost, the MPB will notprint color figures. Labeling should be large enough to be easilyreadable when reproduced to fit within the MPB column format.If at all possible, you are strongly encouraged to supply tables andfigures at actual size for direct reproduction. Tables and figuresintended for direct reproduction to occupy one-half page widthshould be 8.6 cm wide, or full-page width, 17.8 cm. Size yourtables and figures to fit one-half page width whenever possible.
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Minor Planet Bulletin 31 (2004)
Limit the vertical extent of your figures as much as possible. Ingeneral they should be 9 cm or less.
References should be cited in the text such as Harris and Young(1980) for one or two authors or Bowell et al. (1979) for morethan two authors. The reference section should list papers inalphabetical order of the first author’s last name. The referenceformat for a journal article, book chapter, and book are as follows:
Harris, A.W., Young, J.W., Bowell, E., Martin, L. J., Millis, R. L.,Poutanen, M., Scaltriti, F., Zappala, V., Schober, H. J.,Debehogne, H, and Zeigler, K. (1989). “PhotoelectricObservations of Asteroids 3, 24, 60, 261, and 863.” Icarus 77,171-186.
Pravec, P., Harris, A. W., and Michalowski, T. (2002). “AsteroidRotations.” In Asteroids III (W. F. Bottke, A. Cellino, P.Paolicchi, R. P. Binzel, eds.) pp 113-122. Univ. Arizona Press,Tucson.
Warner, B. D. (2003). A Practical Guide to LightcurvePhotometry and Analysis. Bdw Publishing, Colorado Springs,CO.
Authors are asked to carefully comply with the above guidelinesin order to minimize the time required for editorial tasks.
Submission
All material submitted for publication in the Minor Planet Bulletinshould be sent to the editor: Dr. Richard P. Binzel, MIT 54-410,Cambridge, MA 02139, USA (email: [email protected]). Authors areencouraged to submit their manuscripts electronically as emailattachments or as ASCII text, prepared following the instructionsabove. Alternatively, your article may be sent by post on diskette(all diskettes must be accompanied by a complete printed copy ofall material) or as a typed manuscript. When sending material bypost, please include high quality original printed figures and tablesthat can be directly reproduced. In most cases, proofs of articleswill be sent to authors prior to publication.
THE MINOR PLANET BULLETIN (ISSN 1052-8091) is the quarterlyjournal of the Minor Planets Section of the Association of Lunar andPlanetary Observers. The Minor Planets Section is directed by itsCoordinator, Prof. Frederick Pilcher, Department of Physics, IllinoisCollege, Jacksonville, IL 62650 USA ([email protected]), assisted byLawrence Garrett, 206 River Road, Fairfax, VT 05454 USA([email protected]). Richard Kowalski, 7630 Conrad St.,Zephyrhills, FL 33544-2729 USA (qho@bitnik. com) is AssociateCoordinator for Observation of NEO’s, and Steve Larson, Lunar andPlanetary Laboratory, 1629 E. University Blvd., University of Arizona,Tucson, AZ 85721 USA ([email protected]) is Scientific Advisor.The Asteroid Photometry Coordinator is Brian D. Warner, Palmer DivideObservatory, 17995 Bakers Farm Rd., Colorado Springs, CO 80908 USA([email protected]).
The Minor Planet Bulletin is edited by Dr. Richard P. Binzel, MIT 54-410,Cambridge, MA 02139 USA ([email protected]) and is produced by Dr. RobertA. Werner, JPL MS 301-150, 4800 Oak Grove Drive, Pasadena, CA 91109USA ([email protected]). Derald D. Nye serves as thedistributor.
The staff of the Minor Planet Section invites MPB subscribers who are notmembers of our parent organization (Association of Lunar and PlanetaryObservers – ALPO) to join by communicating with: Matthew L. Will,A.L.P.O. Membership Secretary, P.O. Box 13456, Springfield, IL 62791-3456 ([email protected]).
The contact for all subscriptions, address changes, etc. is:
Mr. Derald D. NyeMinor Planet Bulletin10385 East Observatory DriveCorona de Tucson, AZ 85641-2309 USA([email protected])(Telephone: 520-762-5504)
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To minimize our administrative time, please consider subscribing for twoyears. Checks or money orders should be in US dollars, drawn on a USbank, and made payable to the “Minor Planet Bulletin.” To pay by creditcard, (Visa, Mastercard, or Discover) please send by mail your credit cardnumber, your name exactly as it appears on the card, and the expirationdate. Be sure to specify the desired length of your subscription. Creditcard charges will be made through “Roadrunner Mkt, Corona AZ.” Whensending your subscription order, be sure to include your full mailingaddress and an email address, if available. The numbers in the upper-rightcorner of your mailing label indicate the volume and issue number withwhich your current subscription expires.
Articles for submission to the MPB should be sent to the editor. Allauthors should follow the guidelines given in “Instructions for Authors” inissue 30–4 and also available at http://www.MinorPlanetObserver.com/astlc/default.htm . Authors with access to Apple Macintosh or IBM-PCcompatible computers are strongly encouraged to submit their manuscriptsby electronic mail ([email protected]) or on diskette. Electronic submissionscan be formatted either using a Microsoft Word template documentavailable at the web page just given, or else as text-only. A printed versionof the file and figures must also be sent. All materials must arrive by thedeadline for each issue. We regret that diskettes cannot be returned.Visual photometry observations, positional observations, any type ofobservation not covered above, and general information requests should besent to the Coordinator.
* * * * *
The deadline for the next issue (31-3) is April 15, 2004. The deadline forissue 31-4 is July 15, 2004.
