The ASI294MM-Pro

Properties of my ASI294MM-Pro

For an upcoming Echelle spectrograph I bought a new detector, an ASI294MM-Pro. This is my first CMOS chip. I want to present my observations on this detector to show the effect of technical progress.

Please find a more extensive evaluation of the asi294mm-pro at Christian Buil's site.

The ASI294 is operated under Linux on an INDI server. indi_asi_ccd is used as the driver. The client is ccdciel. Gain was 200, offset 8. I have reproduced all measurements also with my old Atik460EX with the driver indi_atik_ccd.


I took 30 bias shots with an exposure time of 0.00032 sec at a temperature of -20°C. The arithmetic mean of these frames give the particular meanbias. The results in the meanbiases and the particular single biasframe bias004.fits are

Frame ASI294 Atik460
Num Pixall116943686045051
Std Devmeanbias3.93.2
Std devbias00041617
ADU ≤ xxxmeanbias≤400: 0px≤200: 0
ADU ≥ xxxmeanbias≥740: 16px≥400: 0px

I show you the 10th column from the right border.

single column from each bias
A column from the meanbias of ASI294 and Atik460.

I took 30 dark frames of 600s exposure time at a temperature of -20°C with my ASI and 23 with my ATIK. 29 rsp. 22 of them were mean averaged and also also a median average of these frames was computed. See the meandark:

mean dark of 29 rsp. 22 frames 600s exptime each
The mean dark frame. Blackpoit and whitpoints are median(frame) ± 104. Move your mouse over the image to see the Atik mean dark.

There is a light in the dark to better find your way home at night.

The two mean darks are not very different.

Property ASI294 Atik460
Mean 570 321
Std Dev 41 104
ADU ≤ xxx ≤400: 0px ≤300: 0px
ADU ≥ xxxx ≥1200: 735px ≥1000: 463px

I made a simple data frame to see what the unwanted lantern does to weak data. My weak signal is 4096 ADU all over the chip. \[\mathrm{sim\_data} = 4096 + \mathrm{remaining\_dark}\] \[\mathrm{pure\_data} = \mathrm{sim\_data} - \mathrm{meandark}\] This simple data reduction removes the glow of the amplifier leaving some noise that comes with every signal. See characteristics of the resulting frame \(\mathrm{pure\_data}\) in the table below and following a plot of the 10th rightmost column in \(\mathrm{sim\_data}\) and \(\mathrm{pure\_data}\) from the asi cam. At last 10th last column of \(\mathrm{pure\_data}\) from cmos vs. ccd.

Property ASI294 Atik460
mean 4087.020 4095.983
median 4086.483 4095.958
std dev 31.66 19.59

The row 8278 in simulated data and the same row in pure data from the CMOS detector in ASI294.
Row 4134 from ASI294 and row 2189 from from the CCD detector in Atik460.

-> comparison of flatfields.

Last modified: 2023 Jan 13