Description of Detector upgrade to LDSS3C
Detector Readout, Gain, Noise:
Slow readout mode (152s read time): gain (low) = 0.16e-/ADU and 0.19e- /ADU (for the 2 amplifier readout); noise = 6 e- with some pattern. There is little reason to use this mode due to the long readout and severe gain with noise that is really no better than Fast readout.
Fast readout mode (28s read time): gain (low) = 1.5e-/ADU and 1.8e-/ADU (for the 2 amplifier readout); noise = 6-6.5 e-
Turbo readout mode (24s read time): gain (low) = 2.7e-/ADU and 3.1e-/ADU (for the 2 amplifier readout); noise = ~10e-
Measured zero points (1e-/s at airmass 1.0) from 140323: [recent reference values from LDSS3 old detector]
Sloan_g = 27.41 [27.45]
Sloan_r = 27.63 [27.52]
Sloan_i = 27.66 [27.26]
Sloan_z = 27.76 [26.36]
Spectral transmission: Measurements by A.Seifahrt 140323
Avoid high flux exposures:
It is requested to keep full frame exposures under 10 full wells per
second (FW/s), i.e. under about 2,000,000 e-/s. Damage to the
detector will most likely
occur at 1000 FW/s. Both, the flux per time and the total flux matter. As a rule of thumb we treat that as a linear effect, i.e. 100s at 10FW/s is as bad as 1s of 1000FW/s. Point sources are no concern, even if they ‘violate’ the above rules. It is total flux on the chip that matters.
(1) Never observe when the sun is above the horizon (i.e. no sky flats with sun above the horizon).
(2) Avoid morning sky flats if possible. At any rate, choose short exposure times (~1s) for the first flats and/or when changing filters to determine save exposure levels.
(3) Never point at the moon.
(4) Switch off Vsub whenever the camera is not in use (i.e. in the morning after the run is over).