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The FIRSTGSC2 Match
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The FIRST Survey is a large-area, high-resolution radio survey using the VLA. 20 cm wavelength ... FIRST catalog and images are online. http://sundog.stsci.edu ... – PowerPoint PPT presentation
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Title: The FIRSTGSC2 Match
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The FIRST/GSC-2 Match
Rick White 2000 October 20 Stevensville, MD
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The FIRST Survey
- The FIRST Survey is a large-area, high-resolution
radio survey using the VLA. - 20 cm wavelength
- 5.4 FWHM resolution (C-configuration)
- 1 mJy detection limit
- 10,000 sq deg of north Galactic Cap
- Matches SDSS current coverage 8000 sq deg
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Current FIRST Sky Coverage
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Southern Sky Coverage
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The FIRST Source Catalog
- First wide-area radio survey with the one arcsec
positions needed for optical identifications - 1 positions (90 confidence) at flux limit
- FIRST catalog and images are online
- http//sundog.stsci.edu
- Current catalog contains 720,000 sources
- 90 sources per sq deg
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FIRST/Optical IDs
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FIRST/GSC-2 Match
- Matched FIRST catalog to GSC 2.1.1
- Used chart.stsci.edu web interface
- 720,000 FIRST catalog sources
- 980,000 GSC-2 counterparts within 24
- Wide match separation allows estimate of
background coincidence rate - 120,000 GSC-2 counterparts within 2
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FIRST/GSC-2 Separation Distribution
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Star Separation Distribution
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Galaxy Separation Distribution
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DRA vs. DDec - All Matches
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DRA vs. DDec - GSC-2 Stars
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Sky DistributionFIRST/GSC-2 Matches lt 2
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Match Magnitude Distribution
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Magnitude Log Distribution
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Comparison with APM Catalog
- Previous FIRST optical matches have used APM
catalog of POSS-I (McMahon, Irwin et al.) - FIRST team has improved APM astrometry and
photometry - APM catalog used for FIRST Bright Quasar Survey
(White et al. 2000), etc. - FIRST/APM/GSC-2 can be used as test
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GSC-2/APM Magnitudes
E(APM) vs. F(GSC-2)
O(APM) vs. J(GSC-2)
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E(APM) vs. F(GSC-2)
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APM/GSC-2 Classifications
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APM/GSC-2 Classifications
Galaxies
Combined
Stars
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Magnitude Log Distribution
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Science with FIRST/GSC-2
- APM catalog has some limitations
- Classifications inaccurate for fainter objects
- Old POSS-I positions have too much proper motion
to find radio stars - FIRST/GSC-2 used to push beyond APM
- E.g., search for red quasars
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FIRST/2MASS 07382750
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FIRST/2MASS 07382750
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SDSS 1044-0125
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Summary
- 120,000 FIRST matches in GSC 2.1.1
- Positions look good on average
- FIRST/GSC-2 matches useful for magnitude test
(faint, good astrometry) - Classification limitations bright galaxies
classified as stars - Good addition to bright training set
- Already valuable for science
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