15
Also, standard format for image storage in astronomy is FITS. While
this format supports 8-bit per pixel, this variant is rather unusual and
16 or 32-bit integer or 32-bit floating-point pixels are typically stored
to disk files to achieve as wide compatibility as possible.
Camera gain
Sensors used in C1+ cameras offer programmable gain from 0 to 24 dB,
which translates to the output signal multiplication from 1× to 15.9×. Gain
can be set with 0.1 dB step.
Note the C1+ camera firmware supports only
analog gain
, which
means real amplification of the signal prior to its digitization. The used
sensors support also
digital gain
control, which is only numerical
operation, bringing no real benefit for astronomical camera. Any such
operation can be performed later during image processing if desired.
Conversion factors and read noise
Generally, all sensor characteristics depend on the used gain. So, we
provide two list of parameters for both minimal and maximal gain.
Camera/sensor parameters for sensors with 3.45 × 3.45 μm pixels:
Digitization
12-bit
12-bit
8-bit
8-bit
Sensor gain
0 dB
24 dB
0 dB
24 dB
Full well capacity
11000 e-
1100 -e
2600 e-
1100 e-
Conversion factor
2.8 e-/ADU
0.3 e-/ADU
10.0 e-/ADU
4.4 e-/ADU
Read noise
2.2 e- RMS
2.0 e- RMS
4.2 e- RMS
9.7 e- RMS
Camera/sensor parameters for sensors with 4.50 × 4.50 μm pixels:
Digitization
12-bit
12-bit
Sensor gain
0 dB
24 dB
Full well capacity
26000 e-
2100 -e
Conversion factor
6.3 e-/ADU
0.5 e-/ADU
Read noise
5.3 e- RMS
3.9 e- RMS
Please note the values stated above are not published by sensor
manufacturer, but determined from acquired images using the SIPS
