Amp glow calibrated has become Black glow???

This seems to happen to everyone one time or another. The solution usually ends up being re-doing the darks. Some have noted that older ASI capture software may change the offset depending on various factors. So in general, check your fits header and make sure your camera settings for both light and dark are exactly the same. APP can accommodate different lengths of exposure by scaling the darks. This has worked well for me. But other than that, the setting should be the same.

@astrogee Here is my fits header, I cant see anything about darks/flats at all. Am I looking in the wrong spot?:

FITS HDUs: 1
HDU1 - SIMPLE = T / Java FITS: Wed Oct 21 22:22:42 AEST 2020
HDU1 - BITPIX = -32 / bits per data value
HDU1 - NAXIS = 3 / number of axes
HDU1 - NAXIS1 = 7120 / size of the n'th axis
HDU1 - NAXIS2 = 4251 / size of the n'th axis
HDU1 - NAXIS3 = 3 / size of the n'th axis
HDU1 - EXTEND = T / Extensions are permitted
HDU1 - BSCALE = 1.0 / scale factor
HDU1 - BZERO = 0.0 / no offset
HDU1 - DATE = '2020-10-22T09:27:55' / creation date of Integration
HDU1 - SOFTWARE= 'Astro Pixel Processor by Aries Productions' / software
HDU1 - VERSION = '1.083-beta1' / Astro Pixel Processor version
HDU1 - INTEGRAT= 'Integration' / integration of light frames
HDU1 - CFAIMAGE= 'no ' / Color Filter Array pattern
HDU1 - NOTE-1 = 'INTEGRATION METADATA'
HDU1 - EXPTIME = 30000.0 / exposure time (s)
HDU1 - NUMFRAME= 46 / number of frames used in this integration
HDU1 - BG-1 = ' 1.1756E-02' / background estimate of channel 1
HDU1 - BG-2 = ' 2.9885E-02' / background estimate of channel 2
HDU1 - BG-3 = ' 2.1168E-02' / background estimate of channel 3
HDU1 - SCALE-1 = ' 2.9620E-04' / dispersion of channel 1
HDU1 - SCALE-2 = ' 4.7518E-04' / dispersion of channel 2
HDU1 - SCALE-3 = ' 3.5563E-04' / dispersion of channel 3
HDU1 - NOISE-1 = ' 7.5899E-05' / noise level of channel 1
HDU1 - NOISE-2 = ' 1.7306E-04' / noise level of channel 2
HDU1 - NOISE-3 = ' 1.1521E-04' / noise level of channel 3
HDU1 - SNR-1 = ' 1.2564E+01' / Signal to Noise Ratio of channel 1
HDU1 - SNR-2 = ' 6.1854E+00' / Signal to Noise Ratio of channel 2
HDU1 - SNR-3 = ' 6.3751E+00' / Signal to Noise Ratio of channel 3
HDU1 - NOTE-2 = 'NR = Noise Reduction'
HDU1 - NOTE-3 = 'medNR = noise in median frame / noise in integration'
HDU1 - NOTE-4 = 'refNR = noise in reference frame / noise in integration'
HDU1 - NOTE-5 = 'ideal noise reduction = square root of number of frames'
HDU1 - NOTE-6 = 'the realized/ideal noise reduction ratio should approach 1 ideally'
HDU1 - NOTE-7 = 'the effective noise reduction has a correction for'
HDU1 - NOTE-8 = 'dispersion change between the frame and the integration'
HDU1 - NOTE-9 = 'because dispersion and noise are correlated'
HDU1 - medNR-1 = ' 5.0404E+00' / median noise reduction, channel 1
HDU1 - medNR-2 = ' 4.9619E+00' / median noise reduction, channel 2
HDU1 - medNR-3 = ' 5.2838E+00' / median noise reduction, channel 3
HDU1 - refNR-1 = ' 5.4792E+00' / reference noise reduction, channel 1
HDU1 - refNR-2 = ' 5.1053E+00' / reference noise reduction, channel 2
HDU1 - refNR-3 = ' 5.4228E+00' / reference noise reduction, channel 3
HDU1 - idNR-1 = ' 6.7823E+00' / ideal noise reduction, channel 1
HDU1 - idNR-2 = ' 6.7823E+00' / ideal noise reduction, channel 2
HDU1 - idNR-3 = ' 6.7823E+00' / ideal noise reduction, channel 3
HDU1 - ratNR-1 = ' 7.4316E-01' / realized/ideal noise reduction ratio, channel 1
HDU1 - ratNR-2 = ' 7.3159E-01' / realized/ideal noise reduction ratio, channel 2
HDU1 - ratNR-3 = ' 7.7906E-01' / realized/ideal noise reduction ratio, channel 3
HDU1 - medENR-1= ' 1.2205E+00' / effective median noise reduction, channel 1
HDU1 - medENR-2= ' 1.0751E+00' / effective median noise reduction, channel 2
HDU1 - medENR-3= ' 1.0201E+00' / effective median noise reduction, channel 3
HDU1 - refENR-1= ' 2.1789E+00' / effective reference noise reduction, channel 1
HDU1 - refENR-2= ' 1.8866E+00' / effective reference noise reduction, channel 2
HDU1 - refENR-3= ' 1.7941E+00' / effective reference noise reduction, channel 3
HDU1 - NORMMODE= 'advanced' / normalization mode
HDU1 - NORMMETH= 'multiply-scale' / normalization method
HDU1 - NORMSCAL= 'BWMV ' / normalization scale/dispersion calculation
HDU1 - NOTE-10 = 'REFERENC tag: used reference frame'
HDU1 - REFERENC= 'Light_M8_300s_Bin1_0001.fit'
HDU1 - COMPMODE= 'full ' / composition mode
HDU1 - REGMODE = 'normal ' / registration mode
HDU1 - REGMODEL= 'projective' / registration model
HDU1 - OPT-DC = 'enabled ' / optical distortion correction
HDU1 - WEIGHTS = 'quality ' / integration weights
HDU1 - INT-METH= 'average ' / integration method
HDU1 - OUTL-REJ= 'adaptive rejection' / outlier rejection filter
HDU1 - OUTL-LN = 'LN rejection' / outlier rejection with local normalization
HDU1 - OUTL-DP = '8 ' / outlier rejection diffraction protection
HDU1 - OUTL-KL = 8.0 / outlier rejection kappa low
HDU1 - OUTL-KH = 4.0 / outlier rejection kappa high
HDU1 - INT-MODE= 'interpolation' / integration mode
HDU1 - INTERPOL= 'lanczos-3-NUOS' / data interpolation & resampling filter
HDU1 - INTSCALE= 1.0 / integrate scale
HDU1 - NOTE-11 = 'PROJECT tag: projection type'
HDU1 - PROJECT = 'rectilinearProjection'
HDU1 - MBBLEND = 'MBB20 % ' / multi-band blending
HDU1 - LNC-DEG = 'noLNC ' / Local Normalization Correction not applied
HDU1 - AD-PED = 0.00511 / adaptive pedestal from data calibration
HDU1 - FILTNUM = 1 / data combined from 1 filter
HDU1 - FILT-1 = 'RGB ' / filter used
HDU1 - SESSNUM = 1 / data combined from 1 session
HDU1 - SESS-1 = 'session 1' / capture session
HDU1 - END

Come to think of it, I think I used lights of different exposures (300s, 600s & 1200s) and darks of 600s. These were fresh darks which had not previously been integrated as master darks (I also had correct dark flats and flats loaded). I wonder if by calibrating with these individual darks and not a scaled master dark may be the issue?

Is there a way to view the workflow log in APP ?

Posted by: @dan-archer

Come to think of it, I think I used lights of different exposures (300s, 600s & 1200s) and darks of 600s. These were fresh darks which had not previously been integrated as master darks (I also had correct dark flats and flats loaded). I wonder if by calibrating with these individual darks and not a scaled master dark may be the issue?

Is there a way to view the workflow log in APP ?

You dont need to correct anything. Just load all your raw darks, flats, bias and lights, into APP. It will save calibration masters and apply appropriately. Later you can use the master calibration frames without loading the original raws.

The file header you showed was the APP output. You need to check the original raw fit headers to see that they all have the same settings, offset, gain, time and temperature. As mentioned, the exposure time can be adjusted for the darks in APP automatically using dark scaling - calibrate tab.

APP can be 100% automatic, try just loading your subs and hit "integrate" - tab 6.

I have noticed with my ASI1600MM that I *have* to use darks with the same exposure time as the lights otherwise I get all kinds of artefacts in the final stack. With my ASI6200MM I can use e.g. 60 s darks with 30 s or 120 s lights and the stack looks nice.

My advice is to take 300 s and 1200 s darks and process the 300 s, 600 s and 1200 s frames in three sessions, one for each exposure time.

HTH, Wouter

I can see "no offset" in the header file. Is that correct? If so, that shouldn't be the case.

@vincent-mod I am unsure of how to adjust the offset using ASIAIR software

@dan-archer, I believe ZWO chooses the offset based on other settings. I heard more recent versions use the same general offset so you might want to update your ZWO software/firmware for more consistency in the offset setting, or use another software to drive the camera, like SharpCap. What offset to use, I read is based on camera noise (floor) which is relative to settings like ISO, exposure time and temperature. A higher offset is used for higher noise floor - i.e. it should exceed the camera noise so that noise is not clipped to 0. This is for the sake of post-processing software like APP itself. My software defaulted to a value of 8 which I think is probably low but seems to work OK - I haven't seen any bad artifacts yet.

@astrogee Thanks for your help, however according to the ZWO firmware website https://astronomy-imaging-camera.com/software-drivers as I have a USB3.0 camera there is no need to upgrade. This is rather annoying, finding it very difficult to capture correct calibration frames with this ASI183MC-Pro and ASI Air. The calibration frames are really hit and miss

@dan-archer I have a friend who has ASI air. I’ll ask him what he does. 

Thanks @astrogee, yes so I don't have an ASIAir, but that's what I noticed in the header. Not sure if it actually sets the offset to 0, but you should confirm with the developers at ASI to see if that is the case or not. I do know that an offset of 0 is not ok as you get a black noise floor.

So my friend with the ASI Air suggest that you use the same software to take the darks as the lights. If you did that with the ASI Air then you would need to make sure the exposure and temperature is the same because there's no other way to control offset.

Thanks, yes I use ASI Air only, and Gain, exposure, and temp are always set the same.  They just turn out differently every now and then.

Sometimes the amp glow is black, sometimes the darks make my integration turn blue as per a previous post of mine https://www.astropixelprocessor.com/community/main-forum/duoband-integration-query/#post-12891  

I don't believe this is a problem with APP, I think the issue lies with the camera. Perhaps there is someone out there with a similar issue?

Thanks for your replies, I think all I can do is keep taking the darks until they are right, and then use the masters for as long as I can before I need fresh ones.

Cheers

Very strange, I would really advice to post this also to the ASI developers, the more people wanting control of the offset the better I think. Strange it seems it's not possible to control.