M103 and M52

Hi all,

A couple of DSO images from early October last year that I'm finally getting processed. I'm not sure why M52 is showing little colour, but it definitely has a 3 colour histogram.

http://web.gccaz.edu/~pmaxson/DSO/M103.jpg

M52:

http://web.gccaz.edu/~pmaxson/DSO/M52.jpg

Paul Maxson

Paul,
Nice clusters. Wow, you must be having great weather to be backloged on data to October.

M103 has that bright red star in the middle and other color. M52 has some color (not as much I think) and should show a little more than you got. I can't explain it.

Paul Maxson said:
.......I'm not sure why M52 is showing little colour, but it definitely has a 3 colour histogram.
M52:
http://web.gccaz.edu/~pmaxson/DSO/M52.jpg

Hi Paul,
Open your M52 in Photoshop or any program that can give you pixel values.
The usual cause for all white stars is that the stars are saturated in all three channels.
The stars in the black band at the top all show saturation in all three channels, hence bright, white stars.
The rest of the stars show mostly equal values in the three channels, which equals white, but they are not all saturated.
I suspect that you lowered the white point on these stars at some point in your processing which is why they are not saturated now. They probably were at acquisition, though.
Most of your stars have a donut appearance. This comes from too aggressive sharpening. I know it's tempting when starting out to call on a sharpening routine to pretty things up, but I would advise you to not do any sharpening until you've mastered the basics. Sharpening works best on really good data and when applied selectively and lightly.
The 'cure' for saturated stars is to take shorter subexposures. When doing a test exposure measure a bright star. A non-saturated red star will have values such as R=230, G=140, B=140, for instance.

I hope this helps,

dan kowall

Hi all,

This is the .fit file I got after combining 100 images of M52. This is the fit file I used to process the final product. If anyone wants to try it, feel free. The fit was created in Nebulousity 1.49.

http://web.gccaz.edu/~pmaxson/DSO/a-M52.zip

Thanks!!
Paul