RFA PixInsight Stacking Problem, Calibration Problem, or... who knows what problem Pleiades Astrophoto PixInsight · DavesView · ... · 4 · 232 · 1

Issue: I receive the failure below when running WBPP. Results in what seems to be vignetting. The below image has had Graxpert, ABE, SPCC and stretched. Saved as jpg. I don't detect vignetting in the subs. Maybe my calibration frames are the problem.



Link to Google Drive 1 each unprocessed light, flat and bias, fits files:

https://drive.google.com/drive/folders/1RXM3SVyxZArLLM2-SeEkS3mdJpj_2fhm?usp=drive_link

Scratch the Google Drive attempt to post the files for download. Just had someone try it and it looks to be a pain in the ass.

Equip: RedCat51iii, ASI294MC Pro, Optolong Ultimate, ASIair+

2024-08-02 17:28:48] * Loading target calibration frame: D:/Astro_Processing/LobsterClaw/NIGHT/NIGHT_N1/Light_LobsterClaw_600.0s_Bin1_294MC_OPTU_gain120_20240801-225041_RC51_0002.fit

[2024-08-02 17:28:48] Reading FITS image: 16-bit integers, 1 channel(s), 4144x2822 pixels: done
[2024-08-02 17:28:48] 77 FITS keywords extracted
[2024-08-02 17:28:48] * Performing image calibration.
[2024-08-02 17:28:48] ** Warning: negative or insignificant pixel sample values detected after calibration.
[2024-08-02 17:28:48] Applying automatic pedestal: 4 DN
[2024-08-02 17:28:48] Calibration range: [-2.537413e-01,1.069428e+00] (truncated)
[2024-08-02 17:28:48] * Writing output file: D:/Astro_Processing/LobsterClaw/calibrated/Light_BIN-1_4144x2822_EXPOSURE-600.00s_FILTER-OPTU_CFA/Light_LobsterClaw_600.0s_Bin1_294MC_OPTU_gain120_20240801-225041_RC51_0002_c.xisf
[2024-08-02 17:28:48] Writing image: w=4144 h=2822 n=1 Gray Float32
[2024-08-02 17:28:48] 85 FITS keyword(s) embedded
[2024-08-02 17:28:48] 
[2024-08-02 17:28:48] [001]

Tim Ray:
I have had the same results with a 1600mmPro camera. My flats were the issue. I was taking very short duration flats (less than 1 sec). I dimmed my light source and expose between 5 and 10 sec flats. The levels were the same but it took longer to get there. Also are you normalizing your subs during the stacking process? 

To verify, stack your lights without calibration frames and see if you have the same result...

CS Tim

Good call! I stacked without the bias/flats... same result. Then I stacked without the darks/flats/bias, and although I had amp glow aplenty, I didn't have the vignetting. Found a masterdark used in a previous successful session and voila. Yep, using normalization. I am currently using sky flats for my OSC setup, so I have to whip them out pretty quickly to avoid a cloud changing the lighting. My mono setup is running NINA and I have a flat panel for it. Going to have to get the OSC rig on NINA. 

Thanks for the tip!

Obviously these messages occur during calibration. They can be related to problematic calibration frames, but from time to time they appear even if the data is "good". To avoid these problems, you can set the offset for your camera. It adds some value to every pixel to ensure that the calculation results are not going to  be negative. If you use an offset, you may try to increase it a little bit. If you don't, just try it. If you are sure, you've done everything correctly, this may be the solution.