Edward BeshoreLunar and Planetary Laboratory
University of Arizona
George DjorgovskiCenter for Advanced Computing Research
Caltech
Killer Asteroids and Exploding Galaxies The Catalina Sky Survey and the
Catalina Real Time Transient Survey
Photo by Rich Kowalski
• Today there are >500,000 catalogued asteroids, most in the main belt
• Those that come closer than 1.3 AU are NEOs, or Near-Earth Objects
The Eventful Universe — March 2010
• Today there are >500,000 catalogued asteroids, most in the main belt
• Those that come closer than 1.3 AU are NEOs, or Near-Earth Objects
The Eventful Universe — March 2010
• Three telescopes– Mt. Bigelow, AZ — 0.7 meter
Schmidt• Vlim ~20 at ~1.5 σ• Field ~8.2 deg2
• Sky 60° > δ > -30° and >20° from galactic plane
• 2.5″ pixels
The Eventful Universe — March 2010
• Three telescopes– Mt. Bigelow, AZ — 0.7 meter
Schmidt– Mt Lemmon, AZ — 1.5 meter
reflector • Vlim ~22 at ~1.5 σ• Field ~1.2 deg2
• ±10° from ecliptic• 1″ pixels
The Eventful Universe — March 2010
• Three telescopes– Mt. Bigelow, AZ — 0.7 meter
Schmidt– Mt Lemmon, AZ — 1.5 meter
reflector– Siding Spring, Australia —
0.5 meter Uppsala Schmidt• Vlim ~19.5 at ~1.5 σ• Field ~4.0 deg2
• Sky -80° < δ < -20° and >20° from galactic plane
• 2″ pixels
The Eventful Universe — March 2010
• Three telescopes– Mt. Bigelow, AZ — 0.7 meter
Schmidt– Mt Lemmon, AZ — 1.5 meter
reflector– Siding Spring, Australia —
0.5 meter Uppsala Schmidt• Identical camera systems
– Spectral Instruments camera with Imager Labs 4K2 CCD thinned by ITL
– ~14 second downloads– CryoTiger cooling
The Eventful Universe — March 2010
• Survey Strategy– Fixed fields– Four (sometimes five) images
10 minutes apart– Typical exposure time 30 sec– Typical “set” consists of 10-12
fields, with up to 15 sets per night
The Eventful Universe — March 2010
• New discoveries of NEO candidates reported immediately to the IAU Minor Planet Center
• Candidates posted to NEO Confirmation Page
• “Incidental” astrometry reported at the end of the night
• Early example of successful pro-am collaboration
The Eventful Universe — March 2010
• Dedicated Followup Telescope• Mt Lemmon, AZ• 1.0 meter reflector • FOV 0.5° on a side• Thinned CCD, Filter wheel• Remote, queued operation• Linked into CSS observing
pipeline• Web accessible• First light late May/early June
The Eventful Universe — March 2010
• Data processing workflow– Calibration
– Read noise ~11 e- due to fast downloads
– Flats constructed from median averaged data
– Unfiltered– Crosstalk artifacts removed
The Eventful Universe — March 2010
• Data processing workflow– Calibration– Object extraction
– Sextractor– Detection thresholds
typically 2-3 pixels at >1.2 σ above sky
The Eventful Universe — March 2010
• Data processing workflow– Calibration– Object extraction– Astrometry
– Typical residuals ~0.2-0.5″– Use UCAC3 catalog
The Eventful Universe — March 2010
• Data processing workflow– Calibration– Object extraction– Astrometry– Moving object detection
– Identify known object– Rate, magnitude, & shape
consistency– Linear motion
• All unidentified detections reviewed by observer
– 5000-6000 detections/night typical
The Eventful Universe — March 2010
• All data placed on a 24 TB RAID system with
• Soon will make all data available via the web using same access software as SDSS
Public Access to Data in Preparation
The Eventful Universe — March 2010
• October 6, 2008 11:39 PM, Rich Kowalski at the Mt. Lemmon 1.5-meter discovers a fast-moving object – 2.5 degrees per day– ~19th magnitude– Reported to MPC immediately– Follow up images begin 82
minutes later
2008 TC3
The Eventful Universe — March 2010
• October 6, 2008 11:39 PM, Rich Kowalski at the Mt. Lemmon 1.5-meter discovers a fast-moving object – 2.5 degrees per day– ~19th magnitude– Reported to MPC immediately– Follow up images begin 82
minutes later
2008 TC3
The Eventful Universe — March 2010
• ~ 570 observations made by 26 professional and amateur observers between time of discovery and impact– 12.4 km/sec– 2-5 meters in diameter
• JPL predicts ~1 kiloton of kinetic energy
The Eventful Universe — March 2010
• Impact predicted over N. Sudan– Predicted 02:45:38– Actual 02:45:40
• Entered atmosphere at 65 km and detonated at 37 km
• An exceptional and successful exercise
The Eventful Universe — March 2010
• For the first time, an object was discovered before entry, observed, and recovered for lab study!
– ~280 meteorites (~5 kg.) recovered
– Named Almahata Sita– A Urelite
The Eventful Universe — March 2010
Catalina Real-Time Transient Survey (CRTS)
• Collaboration with Caltech Center for Advanced Computing Research began in Nov. 2007
• G. Djorgovski, A. Drake, A. Mahabal, R. Williams, M. Catelan
• Uses Palomar Quest detection pipeline• On-site server performs detection in real-time using
deep catalogs, filtering algorithms• Results transmitted to Caltech• CRTS observers classify objects using historical data
from Catalina, others
What’s Next for Catalina?
• Three Small Binocular Telescopes• Largest facility anywhere
dedicated to NEO search• Can be used as three 2.4 meter
telescopes or a single 4.2 meter telescope
• Could cover visible sky ~3 times per month
• Would permit rapid characterization
The Eventful Universe — March 2010
• Dedicated Followup Telescope• Mt Lemmon, AZ• 1.0 meter reflector • FOV 0.5° on a side• Thinned CCD, Filter wheel• Remote, queued operation• Linked into CSS observing
pipeline• Web accessible• New high-speed network• First light late Spring
Results
CSS Archival data used in identifying 2007bi as a pair-instability SN
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Figure 2.
Gal-Yam. et al, Nature, Volume 462, Issue 7273, pp. 624-627 (2009)
CRTS Archival Projects
• CSS observations cover tens of thousands of square degrees since 2005
• Discover and classify variable objects to V~21
• Historical light curves of QSOs, Fermi Blazar targets, SDSS CVs, AMCVn stars
• Light curves for most SDSS spectroscopic targets
• Multi-wavelength studies using sources from NVSS, FIRST, XMM, GALEX, Fermi
• All CSS synoptic data will be made public
More Information
http://www.lpl.arizona.edu/css/Ed Beshore [email protected]
http://crts.caltech.eduA. J. Drake et al 2009 ApJ 696 870-884
Andrew Drake [email protected]
Image Coadds• 100-200 images for most fields in Catalina Schmidt dataset• Limiting magnitude for most single images around V~19.5 (S/N=3)• Median addition of 24 images easily adds 2 magnitudes
The Eventful Universe — March 2010
A. W. Harris, “The population of NEAs and PHAs and the current status of surveys,” final report to NASA NEO Program Office, JPL and NASA NEO Observations Program, Washington, 35 pp., 2007.
30
completion model was "integrated" using the straight line (constant power law) population model, but as we have seen, this model does not fit the derived integral population very well. Summary One of my all time most popular figures, in terms of the number of times it has been copied, with or without permission, appears as Fig. 2-3 in the 2003 NEO SDT Report. An update of that figure, using the newly computed size-frequency distribution, is a suitable summary figure for this report, and is presented in Figure 25. In this figure, we have adopted the population derived using MPC H magnitudes, which results in somewhat lower numbers than using ASTORB or NEODyS magnitudes. The reason we have made this choice is that, in spite of the annoyance of rounding off magnitudes to 0.1 magnitude, the MPC strongly down-weights LINEAR magnitudes when other reported magnitudes are available, thus reducing the bias caused by the 0.18 magnitude systematic offset of LINEAR magnitudes. One can see, in fact, on a close look at Figure 18, that the horizontal offset between the MPC population and the others is about 0.1 magnitude, as one would expect if about half of the magnitudes carry a systematic bias of 0.18 magnitude with respect to the other magnitude base. In comparing H magnitudes of individual objects between databases, this is about the offset that we see. In updating this figure I have also adjusted the secondary scales using new data from this study. The diameter scale is shifted so that D = 1.0 km corresponds to H = 17.75. Although this equivalence was used in the tabular material and text in the 2003 SDT report, the version of the Figure 2-3 published in the report was an older one that still had H = 18.0 as the equivalence between the scales. In the process of deriving a model synthetic population of NEAs for this study, I computed the impact probability of each synthetic object using the Opik algorithm, and also computed the intersection velocity with the Earth (v!), from which one can calculate the impact velocity (vimp) if the object were to hit the Earth from that orbit. For the synthetic population of 100,000 objects used in this study, I find the mean collision probability per object is 2.11 x 10-9 yr-1, or a mean impact interval of 474 m.y. This is a somewhat higher impact frequency than
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This report (2007)Stuart 2001Harris 2002Brown et al. 2002,annual bolide eventConstant power lawfrom 2003 SDT reportDiscovered to 10/31/06
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Figure 25. The new size frequency distribution of NEAs is plotted along with the number of currently discovered NEAs and a few earlier population estimates. Additional scales are included for asteroid diameter and impact energy, and for the mean impact interval.
The Eventful Universe — March 2010
CCD CoolingCryogenic cooling via closed-cycle refrigeration units allow theCCD to be held at -100°C. The near elimination of dark currentallows for zero background imaging with very long exposures.
Data InterfaceThe proprietary gigabit fiber optic interface to the 1300S cameraallows for fast communication and data download from thecamera to the host computer utilizing a free PCI express slot.The flexibility of this interface allows the camera head to belocated many meters away from the controlling PC.
Software InterfaceSpectral Instruments provides our own SI Image SGL cameracontrol software that uses an intuitive graphical user interface
for camera control, image acquisition,viewing, processing and archiving. Inaddition, a TCP/IP server is built into thesoftware allowing another program on thesame computer or from another computerto initiate image acquisition and transfer.SI Image SGL is written in LabVIEW andis provided as a Windows application.LabVIEW and C++ SDK packages areavailable as an option for users who needto extend its functionality or incorporatecontrolling other instruments into asingle program.
CCD Sensor16 ports allow maximum data rates to be reached with thissensor despite its large size. More than 110 megapixels canbe read in less than 10 seconds with less than 10e- noise.16-bit digitization captures the full dynamic range of the80,000e- per pixel dynamic range.
Camera SizeConsidering the size of the sensor in the 1300S camera, thebody is roughly a cylinder 8” in diameter by 12” in length.Bolt patterns at the head can be customized for the end-useapplication. Shown below is the rack mount containing thecryo-tiger and power supply.
Spectral Instruments, Inc.® 420 North Bonita Avenue . Tucson, AZ 85745 . Phone: 520.884.8821 . Fax: 520.884.8803 . Email: [email protected] . Web: www.specinst.com
1300 Series
Finding another TC3
• New camera for Bigelow Schmidt– Increase coverage by 2.4X– Allow nightly searches for TC3-like
objects– Improve understanding of small
object population– Create opportunity for additional
sample recovery– Would allow significant new
transient survey opportunities with a daily cadence for a subset of the sky
The Eventful Universe — March 2010
• Image Characteristics– Rough calibration to V
magnitudes for neutral asteroids using 2MASS colors
– Limiting magnitude at SN=3
• ~19.8 (Bigelow)• ~21.3 (Lemmon)• ~19.5 (Siding Spring)
– Bigelow, Lemmon affected by fringing, particularly at zenith distances > 50°
– Temperature and telescope position-corrected focus
The Eventful Universe — March 2010
• The Data– Archived to DVD by observer– Images lightly compressed
using Hcompress – Sextractor files contain WCS
for each object, corrected instrumental magnitudes, ellipticity, orientation, pixel count, magnitude above sky, processing flags, others
– Image headers contain WCS, central time to ~ 0.5 sec, detector, and telescope data
– ID’d asteroids, validation results, and observations all archived too
– Data to late 2004
BZERO = 32768 BSCALE = 1 DATE = '2009-11-22T08:35:49' ORIGIN = 'CADDSV3.1' INSTRUME= 'SI 600-277' DATE-OBS= '2009-11-22' EXPTIME = 30.0VACUUM = 0. TIME-OBS= '08:35:06.578' MJD = 55157.35789 CAMTEMP = -102.8 OBSERVAT= 'UA Bigelow Station' IMAGETYP= 'OBJECT ' TELESCOP= 'CATALINA SCHMIDT 003'DETECTOR= 'IMAGER LABS' GAIN = 2.6 RDNOISE = 11.6 NCHANNEL= 2 OBJECT = 'U6U00R ' WRA = '06:00:12.06' WDEC = '+31:49:21.8' WEPOCH = 2000.00 SURVEY = 5 SEQNUM = 1 NMINUS = 2 ST = '05:16:59' HA = '-00:43:50' ZD = 9.3
The Eventful Universe — March 2010