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APT specifications

LOCATION (Siding Spring Observatory, near Coonabarabran, NSW, Australia)
Latitude.........................31d 16' 30'' South
Longitude........................149d 03' 40'' East
Altitude.........................1140 metres above sea level

MOUNTING
Declination South limit.........-75 degrees (software limit)
Declination North limit.........+29d 55'    (software limit)
RA West and East limits.........Approx 4h from meridian (software limit)

ENCODERS
RA incremental..................0.045 arcsecs per step, 2500 steps per
                                revolution of the RA motor
Dec incremental.................0.045 arcsecs per step, 1000 steps per
                                revolution of the Dec motor
                    
OPTICS (Baker-Nunn, with modification by UNSW for use with a CCD)
Optical design..................modified Baker-Nunn
Clear aperture..................0.5m
Focal ratio.....................f/1
Mirror diameter.................0.78m
Optically corrected flat field..5 degrees diameter
Filters.........................B, V, R, I, Clear; 5mm thick 80mm dia. 

CCD
CCD sensor used.................EEV (GEC)
Precise plate scale.............9.41 arcsec/pixel
Pixel format....................770 columns x 1152 rows
Field of view covered by CCD....3 degrees (E-W) x 2 degrees (N-S)
Image format with overscan......800 columns x 1200 rows
Pixel size......................22.5 microns square
Readout speed settings..........slow                    fast
Readout noise...................4.7  e-                 8.9  e-
Low gain........................20.4 e-/ADU             21.6 e-/ADU
High gain.......................5.1  e-/ADU             5.4  e-/ADU
Pixel read cycle time...........35 microsec             5.5 microsec 
Vertical transfer cycle time....3.0                     3.0
Typical frame readout time......34s                     6s
Cooling.........................Thermoelectric stable at 200K after 15.5 minutes
Dark current....................<0.8 e/pix/s (0.73 e-/pix/s 300s exp)
A->D converter..................16 bits from 0 to +65535 counts
Bits per pixel..................-16 bits/pixel in FITS header (unsigned 16-bit integer)
Pixel electron well depth.......420,000 e-

Note: dark current may be non-linear with time. It may rise from a negligible
value under about 100sec to about 1 e-/pixel/s for exposures >> 300s.
The dark current for a particular exposure time should be determined 
if accurate dark current subtraction is critical.



Michael C. B. Ashley
Wed Jun 5 14:40:19 EST 1996