WBPP for different Gains

Bruce Donzanti

I have subs with the same filter and exposure time but 2 different gain settings. I also have darks, flats and dark flats from both gain settings.  When I load all of the Ha subs, they are listed under 300s exposures- gain is not identified.  Same for the darks, flats and dark flats.  Can someone explain if and how I can set up WBPP to integrate these data?  Do I need to add the specific gain value as a keyword for the appropriate light, flat, dark flat and dark so they are grouped that way?  The two different gain settings are listed in the fits headers.

Bruce Donzanti

I think I figured it out.

BlockHead

Hi Bruce,

If everything was consistent in the headers- you could simply use a preprocessing keyword called "GAIN" and your data would be grouped for calibration matching the gain setting as written in the headers of files. This is something I explain and demonstrate in many tutorials. Did you find this solution? Were the videos of help in solving the issue?

-the Blockhead

Bruce Donzanti

Thanks, Adam.  My headings are consistent.  I watched 2 of your videos on this topic and they are helpful, but I posted the question in haste and then jumped to my own conclusions as to how to do this instead of watching the other videos.  At first, I used both 300 and 100 (the two gain settings) as preprocessing keywords and then realized after it started running that I may have made a mistake.  Re-running it just with "gain" gave me the answer I was looking for.  

BlockHead

Correct.

The Keyword is the thing the files have in common... the "values" (in this case 100 and 300) are the things that will be grouped. 

Good work!

-the Blockhead

Bruce Donzanti

After combining the different gains and using your calculation on the use of a pedestal when required (great video on that), I was able to get a decent image of the faint planetary nebula, PK164+31.1 (Jones-Emberson-1), from my light polluted suburban area.  It took 22 hrs of data using my C11" EdgeHD @ f/10 (o.27 arcsec/pixel) with an ASI6200mm but I was pleased with the result.  

Thanks to both of your videos on WBPP grouping and use of a pedestal (the 100 gain did not require a pedestal but the 300 gain needed a small one) and your help here made this work out for me.

Bruce Donzanti

I am back to this problem again.  I captured data both at a gain of 100 and 300.  I have darks, flats, and dark flats at both gains.  The fits of all the file types all show gain as 100 or 300 as expected.  Yet, when I place them in WBPP and use GAIN as a keyword, I am getting an error of the 300 gain light frames as "new data".  I haven't seen this before and the lights captured at 300 gain are clearly indicated on the fits files.   If I enter the 300 gain data alone, no problem.  If I enter the 100 gain data, no problem.  It is only when I try to combine them and use the keyword of gain that the issue occurs.  

Any idea what I am doing wrong?

BlockHead

Hi Bruce,

What you have not shown are your file names (or path).

File names and path take precedence over FITS key words.  

I would wager that "New Data" is in your path statement...and likely there is preceding "Gain" before it??

WBPP isn't making a judgement... "New data" must be something you created.

Does this make sense?

-the Blockhead

Bruce Donzanti

ahh....I never would have figured that out!  

Attached was the file path with "new data" in it

When I simply put those data into the other folders containing the 100 gain files, it worked. 

Thanks, Adam.  I would have been pulling the rest of my hair out, trying to figure this out!