First Data from the Fermilab Drift Scan Camera
Session 27 -- Digitizing the Sky
Display presentation, Tuesday, 31, 1994, 9:20-6:30

## [27.02] First Data from the Fermilab Drift Scan Camera

Chris Stoughton (FNAL), Jim Annis (FNAL), Steve Kent (FNAL), Richard Kron (FNAL), Jonathan Loveday (FNAL), Tim McKay (FNAL), Heidi Newberg (FNAL)

The Fermilab Drift Scan Camera contains a single Tektronix/SITe $2048^2$ CCD and serves as a prototype for the Sloan Digital Sky Survey. The camera is on the 41'' reflector at Yerkes Observatory. We have completed a section of a great circle survey near the celestial equator, 8$h$ long and $20^\prime$ wide, using four filters which approximate the colors $V$, $R$, $I$, and $z^\prime$. The last color, $z^\prime$, is centered at 9250 $\AA$ with FWHM of 1450 $\AA$, and will be used in the Sloan Digital Sky Survey.

The effective exposure time of 80 seconds gives a limiting magnitude of 20 in $I$. By tuning the detection parameters (\# connected pixels, and significance above sky) we detect low surface brightness objects (central surface brightness of 21 $mag/arcsec^2$ in $I$) and reject noise. We measure isophotal magnitude to a surface brightness of 24.5 $mag/arcsec^2$ in $I$, aperture magnitude, radial profiles, and weighted moments in each color.

The object finding and measuring software is specific to the Drift Scan Camera, although the framework'' software (FITS i/o, storing object parameters, etc.) and commercial object oriented database (Versant) are those used by the Sloan Digital Sky Survey. Thus, tools for data analysis which we develop let us see how to handle the similar, but significantly more volumnious, Sloan Digital Sky Survey data.

The photometric calibration is from Landolt standard stars, and we then compare to objects in the HST Guide Star Catalog to check the photometry and calibrate the astrometry. Repeated scans on sections of the survey check the calibrations. These data allow us to study the global properties of stars and galaxies in the 40 square degrees of our survey, free from systematic biases inherent in large-angle photographic surveys.