M51 Processing data from Josep Drudis -- Thanks!

Roger Smith

Hi Adam,

I watched all these M51 Fundamental Processing videos last month, and now doing the actual processing. I have learned a lot and like your explanations, thought processes and enthusiasms you show all of us. Thank you! I know your starting intention was to produce a step by step method for newer PI users, but you faced the reality that the red data made it necessary to apply more than step by step. I appreciate this because if following others' online step by step guides, they would not tell you how to examine the result (red donuts around all stars) and how to fix it. You are the best instructor!

During my M51 processing I am using the current version WBPP2.1.2 which simplified the loading and confirming it was set up properly. I then used the NSG1.4 script to set the NWEIGHTS for each LRGB sub. After star registration and integration I think the result quite good (I am not brave enough to say better than yours!). I ended up with none of the black artifacts showing in your processing, and the stars K values a bit brighter. 

For the 'correcting' for the large red stars. I made the star mask, applied it and then eroded the outer portion of the red stars, same as you did. I think results good (similar). Actually I found it amazing you could "fix" the red, including the shift the red vs green and blue. I again learned a lot.

My questions:   

If you were re-processing the same M51 data would you approach the red stars size reduction the same way as your video, or is there a good alternate way to try?   

Would your new video on Star De-Emphasis be an alternate way to approach the red problem, and using a game mask to protect the galaxy? Of course on the extracted red channel.

I told my wife that I learned from you that I could either spend 2 minutes focusing my scope carefully, or 2+ hours compensating for bad focusing! We both agreed, The devil is in the details.

Roger

BlockHead

Regarding the red stars- they were really badly out of focus. This is the only "reasonable" (kinda) way I know. Star-Deemphasis would also work...but likely be more steps than necessary. Keep in mind we are fixing the color here... not detail (not luminance)- When using StarDe-emph it is done on a full color (including lightness/detail) image. 

I am glad you enjoyed the information and I appreciate the feedback.

-the Blockhead