OCRA-pscience projects

Marcin Gawroński

Bonn 14.III.2011

OCRA-p Marcin Gawroński Bonn 14.III.2011

Observations Observations withwith OCRA-p OCRA-p

- two - two modesmodes of of observationsobservations (for (for brightbright and and weakweak sourcessources))

- one - one primaryprimary fluxflux densitydensity calibratorcalibrator (NGC 7027, Hafez et al., 2008) (NGC 7027, Hafez et al., 2008)

- - correctioncorrection of of atmosphericatmospheric absorptionabsorption is is basedbased on on measurementsmeasurements of T_Sys of T_Sys at at zenithzenith and z=60 and z=60

- - gaingain elevationelevation functionfunction is is estimatedestimated usingusing the the seriesseries of NGC7027 of NGC7027 measurementsmeasurements at at differentdifferent elevationselevations

- - fluxflux densitydensity errorserrors at at levellevel of 5-8% of 5-8%

OCRA-p Marcin Gawroński Bonn 14.III.2011

Modes of observationsModes of observations

1. Cross-scans (>100 mJy)

OCRA-p Marcin Gawroński Bonn 14.III.2011

Modes of observationsModes of observations

2. „On-off” Observations

OCRA-p Marcin Gawroński Bonn 14.III.2011

Modes of observationsModes of observations

2. „On-off” Observations

Limits of the „on-off' methodLimits of the „on-off' method::

- - duedue to to accuracyaccuracy of of pointingpointing and and trackingtracking additionaladditional position position calibrationcalibration is is neededneeded

- - cross-scanscross-scans on on nearbynearby brightbright sourcessources (<4 (<4oo, F, F30GHz 30GHz > 150 mJy)> 150 mJy)

- position - position calibrationcalibration everyevery 30-40 min 30-40 min

- single - single „on-off' observation ~5 min, single cross-scan ~7 min„on-off' observation ~5 min, single cross-scan ~7 min

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - CJF Science projects - CJF

CJF CJF surveysurvey

- test project, - test project, comparisoncomparison of of ourour resultsresults to to otherother from the from the literatureliterature

- - 293 293 sourcessources fromfrom CaltechCaltech – Jodrell Bank – Jodrell Bank FlatFlat spectrum spectrum surveysurvey

- S4.8 GHz > 350 mJy

- (1950) 35º

- |b| 10º

- 1.4-4.8 GHz>-0.5 (S)

- observations in the „qscan” (cross-scan) mode (IV-VII 2005)

- results published in Lowe et al. 2007

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - PNe Science projects - PNe

Planetary nebulae survey with OCRA-p

Aims:- test the spinning dust emission hypothesis in the case of PNe- prepare a small sample of source which can be used as a future flux calibrators

Observations:- 442 objects from Acker et al. 1994 ( > -15º) - „blind” survey in the „qscan” mode (XII.2005 – V.2007)- detection of 93 PNe

Results (Pazderska et al. 2009): - for 41 objects free-free emission models were calculated based on Siódmak & Tylenda (2001)- model fits well to observations and hence no need for additional emission mechanism

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - VSA Science projects - VSA

Survey of sources from Very Small Array fields

Aims:- measure the flux densities of 121 sources in VSA fields selected at 15GHz with the Ryle telescope- investigate the spectral index distribution of weak sources- estimate the surface density of sources

Observations:- in the „on-off” mode (2007 -2009)- ~5 mesurements per source

Results (Gawronski et al. 2010)- the estimated surface density of sources with F

30GHz>10 mJy of

2.0 0.4/deg2 is in a good agreement with previous results (eg. Mason et al., 2010)- the proportion of steep spectrum sources increases with decreasing flux density (de Zotti et al., 2005)- no evidence for an additional population of sources with inverted spectra

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - VSA Science projects - VSA

Spectral index distribution

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - VSA Science projects - VSA

Variability of weak sources

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - CRATES Science projects - CRATES

Observations of the Combined Radio All-sky Targeted Eight-GHz Survey (CRATES) sample with OCRA-p

Aims:- improve the knowledge about radio sources populations in the range ~2-200 Ghz- measure the flux densities of the selected subsample from CRATES (|b| 15º, 1.4-4.8 Ghz>-0.5, 75º > >31º)

Observations:- in both modes, for sources with f

30_est>100 mJy „qscan” mode was

used, for f30_est

<100 mJy „on-off” mode was used- XI.2008 -VI.2010, ~6 mesurements per source

Results (Peel et al. 2011):- 34 candidate GPS sources (5.4% objects from selected sample)- variability implies that simple source substraction strategies in CMB studies can be subject to considerable uncertainty- good corelation between the 30GHz flux densities and Fermi gamma-ray flux densities

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - CRATES Science projects - CRATES

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects - CRATES Science projects - CRATES

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects – SZ effect Science projects – SZ effect

Observations of the Sunyaev–Zel'dovich (SZ) effect inGalaxy clusters

Aims:- measure the SZ effect in well selected galaxy clusters sample- estimate the properties of IGM- investigate the cosmological evolution of GC

Observations:- long integrations in the „on-off” mode- observations of trail field separated from the target fields by 20' in RA over the same range of hour angle after each cluster observation- 2006 – 2011

Results (Lancaster et al. 2007, Lancaster et al. 2011):- detections of the SZ effect in 21 most X-ray luminous clusters (4+17)- background source contamination is an important issue - estimated scaling relations between various cluster parameters are in good agreement with the self-similarity model (Morandi et al., 2007)

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects – RS Oph Science projects – RS Oph

International follow up of the RS Oph outburst in the radio part of the continuum

- the latest outburst of the recurrent nova RS Oph was discovered on 12.II.2006

- observations were done in the on-off mode

- MERLIN, VLBA, VLA, Effelsberg, GMRT, OCRA-p (1.4 – 30 GHz)

- all data published in Eyres et al. 2009 and Eyres et al. 2010

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects – RS Oph Science projects – RS Oph

Results

OCRA-p Marcin Gawroński Bonn 14.III.2011

Science projects – V407 Cyg Science projects – V407 Cyg

OCRA-p follow up of the outburst of the symbiotic nova V407 Cyg

- the outburst was discovered on 10.III.2010- OCRA-p made a series of measurements during next 5 months- results were published in the Astronomer's Telegram #2511 & #2905