Update on the Medusa Nebula

 A few days ago I posted my image of the Medusa nebula. I had mentioned that there were some problems with the level of Sii data and that the blue star subs were really bad.

It turns out there were other issues as well - having to do with the settings used to calibrate and stack the narrowband subs. I sent my raw data files to a fellow astrophotographer out on Astrobin, Uwe Deutermann, and he was able to process them with no such issues and create a much better final image. Here is that result as a collaboration effort of the two of us: my data, Uwe's processing.

Medusa Nebula -- Abell 21, Sh2-274

Later on another astrophotographer on Astrobin, George Yendrey, provided a very complete evaluation of my issue with the processing and uncovered an incorrect setting/parameter I was using in calibrating the subs. Once I set the parameter correctly I was able to reprocess my data and get similar results to what Uwe had provided. Such is the huge benefit of having an online collaboration site like Astrobin where fellow astrophotographers can ask questions, and exchange knowledge.

The complete dialog of the journey to get this image can be found on Astrobin.

The Medusa nebula

Got some clear nights as of late so I immediately got the scope out under the stars to do some imaging.

Seems like everyone as of late is posting the Medusa nebula on Astrobin.  Mine is no where as good as any of them, but it is the object I used to check on my recently returned EdgeHD11 from Celestron (had it in for cleaning and maintenance) and my new Optolong filters and 2" FW. 

The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula. It is 1,500 light years distant spanning about 4 light years across.

I had lots of problems getting this object imaged. One is the lack of sufficient data in S2. The other was the fact that the focus on the Blue filter was off and so I got some wonky stars. Oh well, enough of the sad commentary, here it is.

The Medusa nebula - SHO w/RGB stars
March 19, 21 and 26, 2023
EdgeHD-11; ASI2600mm  -  9 hours Integration Time

There was another issue I had but that is potentially going to be discussed in a later post. I didn't do any calibration on these subs - no darks, no flats. This was because of something that was occurring in the PixInsight WBPP script that essentially wrecked my Ha stack. The O3 and S2 data were fine. Not sure why this happened, but I am researching it.

More details on this imaging run can be found on my Astrobin site.