Help with M104

Questions and answers about processing in StarTools and how to accomplish certain tasks.
mhamburg
Posts: 34
Joined: Mon Sep 08, 2014 12:40 pm

Re: Help with M104

Post by mhamburg »

I doubt it because my rig is under a dome in my observatory, but I wasn't looking for any moisture. What intrigues me (okay, :cry: annoys me) is that I might not have the best settings in DSS. Can someone chime in, please?
Michael
User avatar
admin
Site Admin
Posts: 3381
Joined: Thu Dec 02, 2010 10:51 pm
Location: Melbourne
Contact:

Re: Help with M104

Post by admin »

I think the oddly shaped stars are more of stacking problem, trying to stack stars that have been deformed by coma in some frames but not in others, or some other aberration. It happens unfortunately. I don't see any clipping though...
Ivo Jager
StarTools creator and astronomy enthusiast
Rowland
Posts: 235
Joined: Sat Mar 05, 2011 10:54 pm

Re: Help with M104

Post by Rowland »

I've lost track of which version we are talking about. I sampled the pixel values in the second dropbox link in the first post. The processed stack? I thought.

This is the latest dropbox image. I am presuming a single light sub, uncalibrated. No master flat, no master bias (fixed pattern template), no master dark application? Pixel values are OK.

Can you send me a bias and an uncalibrated dark and uncalibrated flat for this image. Just as they came out of the camera - tiff or png is OK to keep the file size down. I'll just convert the sub to whatever you send. Narrow things down and see what's going on, if that is OK with you?

There is no evidence of weird stars. They look OK. I'm not the expert but I find certain techniques produce better results.
Attachments
Pixel values
Pixel values
M104pv.jpg (41.11 KiB) Viewed 7951 times
Pretty picture
Pretty picture
M104.jpg (39.22 KiB) Viewed 7951 times
mhamburg
Posts: 34
Joined: Mon Sep 08, 2014 12:40 pm

Re: Help with M104

Post by mhamburg »

DARK_120s_1600iso_+11c_20150419-02h32m33s894ms.jpg
DARK_120s_1600iso_+11c_20150419-02h32m33s894ms.jpg (475.48 KiB) Viewed 7949 times
Hi Rowland,
I can only post a resized individual dark frame (120s @iso1600). Unfortunately, I wasn't able to shoot any flats and I usually don't shoot bias either. I hope this helps a bit. Many thanks for your help.
Michael
Rowland
Posts: 235
Joined: Sat Mar 05, 2011 10:54 pm

Re: Help with M104

Post by Rowland »

Can you upload a dark fits to dropbox, it's near impossible to work with jpeg due to compression.

In hindsight, :character-oldtimer: and while flats are highly desirable, if the only calibration to this image is dark frames, it's likely the problems lie elsewhere than calibration. The application of a stack of darks is optimal for DSLR data, and as far as DSLR images are concerned, the only purpose of bias frames is to calibrate flats - and so, unlikely that calibration truncated the pixels :chores-chopwood: :teasing-blah:
mhamburg
Posts: 34
Joined: Mon Sep 08, 2014 12:40 pm

Re: Help with M104

Post by mhamburg »

Here is the link to the dark raw file. I hope this helps the analysis.

https://www.dropbox.com/s/i8zpqt4awp569 ... s.CR2?dl=0
Rowland
Posts: 235
Joined: Sat Mar 05, 2011 10:54 pm

Re: Help with M104

Post by Rowland »

Michael.

It just occured to me that the fts file is a stack. If your patience is not strained to breaking point, a single light .CR2 file is what's needed. Have you compared your light frames to the stack individually? On second look the values in the fts file are not what they should be.
mhamburg
Posts: 34
Joined: Mon Sep 08, 2014 12:40 pm

Re: Help with M104

Post by mhamburg »

Hi
Rowland,
Let me provide a link to a single raw light: https://www.dropbox.com/s/51k6jpi50fxl3 ... s.CR2?dl=0
Rowland
Posts: 235
Joined: Sat Mar 05, 2011 10:54 pm

Re: Help with M104

Post by Rowland »

Michael.

A quick look before heading off to work. I think the subs are too short, or possibly the focal ratio to high for the subexposure time. The images calibrate quite well but the remaining values are quite low with a very noisy background. At a glance raising the background is probably the key thing here. I imaging that DSS may not have helped and the settings are probably critical. If you can, in DSS, stack your darks separately and then apply the master to your light frames. Don't apply pixel rejection to your darks, if that is the default in DSS and use an average combine, with no noise evaluation, if DSS does that - just a plain unadulterated stack applied to your light frames. See how that goes.

ST will handle the noise very well. But there is not a lot of data in total to start with.
mhamburg
Posts: 34
Joined: Mon Sep 08, 2014 12:40 pm

Re: Help with M104

Post by mhamburg »

I will follow your advice and thanks for the continued support. Michael
Post Reply