Can we do sensor analysis with ASTAP, when I asked about this on cloudy nighths it was sugested that I try sharpcap or pixinsite. Both are out of my reach though.
Some things I am interested in know are read noise, well depth, maybe even dark current at different temperatures.
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Yes that is possible. The only thing you have to do is to set the ADU to electron factor in the popup menu statusbar. (not persistent) If the value is already in the fits header then it will propose it. If not you have to enter the correct factor manually. Then the noise will be displayed in eletrons and not ADU.
Then with the viewer popup menu you can display the statistics (of a dark).
That should be enough to analyse a series of dark at different exposure length, temperatures and binning. There is no automation as in SharpCap, so it is a manual excersise.
Hope this helps, Han
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Ok I figured out how to do it and did try it on a few files but I think it may be broken on the mac end. When I select e- from the status menu it still give me a sigma value. And the value apears to be the same too..
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Now can I tell what the well depth of the camear is with this tool as well? As in how many photons of light the pixel can take before hitting saturation?
Last edit: Grimstod 2022-04-19
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I'm surpriced it is so high (20000) for an ASI1600. I operate it normally in unity gain, so 1 e- per ADU. Since it is 12 bit, for maximum output it contains about 4094 electrons. The output is multiplied with 16 to get an output 0..65535.
It think you could measured by applying a low gain. If the actual gain is less then 0.2 you should see saturation below about 65000. Unity gain is camera gain=139, so you should look it up which gain is required for this.
Han
Last edit: han.k 2022-04-19
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I think using the maximum well depth is only interesting if there is a huge amount of light. So for terrestrial images. For astronomy you better stick to unity gain at 139.
At my location SQM<20.4 the sky background noise is still overwhelming. The ASI1600-MM Cool camera readnoise noise is much lower then the sky background noise.
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Can we do sensor analysis with ASTAP, when I asked about this on cloudy nighths it was sugested that I try sharpcap or pixinsite. Both are out of my reach though.
Some things I am interested in know are read noise, well depth, maybe even dark current at different temperatures.
Yes that is possible. The only thing you have to do is to set the ADU to electron factor in the popup menu statusbar. (not persistent) If the value is already in the fits header then it will propose it. If not you have to enter the correct factor manually. Then the noise will be displayed in eletrons and not ADU.
Then with the viewer popup menu you can display the statistics (of a dark).
That should be enough to analyse a series of dark at different exposure length, temperatures and binning. There is no automation as in SharpCap, so it is a manual excersise.
Hope this helps, Han
Ok I figured out how to do it and did try it on a few files but I think it may be broken on the mac end. When I select e- from the status menu it still give me a sigma value. And the value apears to be the same too..
Wait I spoke to soon. Here is what I got. 10s dark 93 of them stacked together. Does this look right? Seams like 0/.2 is really low?
x̄ : 254.96 (sigma-clip iterations=4)
x̃ : 254.96
Mo : 255
σ : 0.2 e- (sigma-clip iterations=4)
σ_2: 0.2 e-
mad: 0.2151
m : 248.89
M : 2760.7 (1 x)
Flux: 7.90E+05
≥64E3 : 0
Vignetting [Mo corners/Mo]: 0%
Bit depth data: 18
Ok a single image shows a more realistic number. Looks like 2.9e for this setting with the camera.
Ok a single image shows a more realistic number. Looks like 2.9e for this setting with the camera.
Now can I tell what the well depth of the camear is with this tool as well? As in how many photons of light the pixel can take before hitting saturation?
Last edit: Grimstod 2022-04-19
93 darks should decrease the noise by sqrt(93). So 2.9 e- dived by sqrt(93) is 0.3 e-. So that looks okay.
The bith depth is reported in your previouse post as:
Bit depth data: 18
For a single image with stars you should get 12, 14 or 16 depending on your camera. For more images it increases
Hopes this helps,
Han
OK good I did see those but that does make more sense now.
How about thought the number of photons of light each pixel can handle? I see this listed in specs for a lot of digital cameras.
Here is an example of the ZWo 1600MM
https://astronomy-imaging-camera.com/product/asi1600mm-cool
I'm surpriced it is so high (20000) for an ASI1600. I operate it normally in unity gain, so 1 e- per ADU. Since it is 12 bit, for maximum output it contains about 4094 electrons. The output is multiplied with 16 to get an output 0..65535.
It think you could measured by applying a low gain. If the actual gain is less then 0.2 you should see saturation below about 65000. Unity gain is camera gain=139, so you should look it up which gain is required for this.
Han
Last edit: han.k 2022-04-19
That number is for gain 0. At 139 the well depth must be much lower but I have not figured out how to read that though.
I think using the maximum well depth is only interesting if there is a huge amount of light. So for terrestrial images. For astronomy you better stick to unity gain at 139.
At my location SQM<20.4 the sky background noise is still overwhelming. The ASI1600-MM Cool camera readnoise noise is much lower then the sky background noise.