NEAT/PALOMAR INSTRUMENT DESCRIPTION
Dr. Steven H. Pravdo
Jet Propulsion Laboratory
California Institute of Technology
4800 Oak Grove Drive
Pasadena, CA 91109
(818) 354-3131 voice
(818) 354-8887 fax
The NEAT/Palomar instrument on the Oschin telescope is a CCD camera, consisting of three
separate 4Kx4K front-side illuminated arrays in separate dewars arranged in a linear array
Pixels: 4080x4080 15 micron pixels in each of 3 arrays
Plate scale: 1"/pixel. One 3-array image covers ~3.75 square degrees.
Gap between arrays: ~ 1 degree
Stellar image size: 1-2 pixel (plus seeing) with some edge-of-fields degradation
Bandpass: no filters, covers 400-900 nm with typical front-side illuminated CCD quantum efficiency, peaking near 50% at 650 nm.
Cooling: TECs achieve operating temperatures ~-40 C.
Readout time: ~30 sec in 4 parallel channels/array, and each array in parallel.
Dynamic range: 16 bits/pixel but saturation occurs in s/w near DN (cts) ~20K
Arrays A,B,C have similar performance. As of 2002, Array A has higher noise in its northeast quadrant, which is typically not used in
A 60-s exposure reaches V~21
Read noise (est.) ~ 10 e-, gain ~2
Dark time background = 23 cts/pixel/sec
E.g. V=19 object, G-type spectrum yields 29 cts/sec
Lowest practical exposure time without duty cycle penalty is ~30 sec. The lowest exposure time is 1 sec.
Observer provides a script for all-night autonomous operations. The script contains one line for each observation. The observation
parameters are: RA (decimal hours) and Decl. (decimal degrees) J2000, the exposure time, the number of exposures and the revisit time
between exposures. NEAT operations typically take three 60-sec exposures in 15-min intervals.
The overhead time between exposures taking into account readout and telescope motion is ~50 sec.