Pixinsight - Pre-Processing Problems

[Kaliska]

Hi, I've been collecting quite a lot of data over the past few weeks, which i am now trying to process. I'm using the PI BatchPreprocessing but I;m getting awful results and I can't figure out why? I've uploaded my files on the OneDrive if there is anyone out there who could kindly give me their honest opinion on the data I've got. I'm using an ASI-1600mm cool with a TS100Q, SGP and PI.

The files can be found here https://1drv.ms/u/s!AsOwCeIp2jCOh0tlJgU_tWjq656k?e=mbbG5L

The image below is calibrated with 50 Flats and Darks in PI.

Edited May 3, 2020 by Kaliska

[MarkAR]

Did you take Bias frames ? they might help.

It looks like your flats might have over corrected the vignetting or you're getting amp glow/ light seepage in the corners.

Noise wise the galaxy looks fine, maybe just crop out the corners.

[Kaliska]

No Bias frames were taken, I always been under the impression that they are not needed for this type of camera/chip.

[MarkAR]

Ok, I thought the ASI1600 was a mono ccd, if it's CMOS then batch preprocessing is not ideal.

Have a look at Chris Woodhouse vids on YouTube, goes through the process for CMOS.

[Laurin Dave]

With the ASI1600 you need to use matched darks and flat darks and calibrate with "Optimisation" turned off..  Pretty sure there's now a way to do this in the BPP script although I don't use it..   Your darks match your lights but you do not appear to have flat darks with which to calibrate your flats.. so you need to take some flat darks to match your flats, however, I looked at one of your flats and the FITS header says CCD temp of 8.8 C and a set temp of -9.1 C so something was amiss there and you may need to retake your flats..  if all of them were at the same temperature then you could take matching darks although if it was at 8.8 C they might be a bit noisy.  

[Kaliska]

Again, I was under the impression the temperature of the camera isn't a factor when producing flats as they are for removing visual aretfacts and not noise. I've just got a new flats panel so I'll take some tonight at -20 along with some dark flats to see if this helps.

[Star101]

Is there moisture in the camera or on the filters?

Check the camera by looking at the chip with no power...Then add power and cool the chip for 10 mins...Look at the chip again. Is there any condensation/colour change? 

I had similar issue a few months ago...Once I dried the camera and the OTA, All was OK again. 

I dried the camera tablets by placing them in the microwave, medium power, for 2 mins. Then pop them back in the camera while still warm.

I'm not saying this is the issue you have....But it worked for me.

 

Good luck and let us know when you find the answer.

 

Dave

[Laurin Dave]

10 minutes ago, Kaliska said:

Again, I was under the impression the temperature of the camera isn't a factor when producing flats as they are for removing visual aretfacts and not noise. I've just got a new flats panel so I'll take some tonight at -20 along with some dark flats to see if this helps.

They don't need to temperature match your lights but its just best to do them with cooling as that minimises overall noise ..  I suspect that the overcorrection is caused by the incorrect or lack of calibration of your flats..  what messages did BPP throw up when you started it?   Your new flats and flat darks should sort it 

 

 

[Kaliska]

10 minutes ago, Laurin Dave said:

They don't need to temperature match your lights but its just best to do them with cooling as that minimises overall noise ..  I suspect that the overcorrection is caused by the incorrect or lack of calibration of your flats..  what messages did BPP throw up when you started it?   Your new flats and flat darks should sort it 

 

 

There were messages coming up "no correlation between master dark" which I've just noticed.

[City9Town0]

I found this a great help when starting out two years ago...

https://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html