M31 image

[Kevdan]

Hi All,

I had a great night last night as im sure most of us did, I took a series of 25 1minute exposures of M31, (However this took 1 1/2 hours due to my camera being so slow when processing)

Ive run the images through DSS but can not get hardly any detail from it, I can see M110 quite easily but the detail of M31 eludes me, what else do i have to do to get the detail, I have got photoshop cs5 and even when i adjust the curves and levels (after changing to 16bit) nothing realy comes out.

Any help realy apreciated.

Kev.

[umadog]

I image other stuff, not astro-related, but I think the (or at least a) problem may be the large number of exposures. Reading from the chip adds noise to the image because the little amplifiers inside the CCD are not noise-free. Consequently, a single 25 minute minute exposure will contain less noise than 25 exposures of 1 minute each.

What do the individual frames look like? Is there anything recognisable on them at all? If there isn't, then maybe this is throwing off the stacker. Perhaps there's something you could do to improve the quality of the individual frames even at 1 minute exposures? Have you taken dark frames and subtracted those? That will help because things like hot pixels are in the same place on each frame and will confuse the stacker. Removing the noise due to the dark current will also clean up the images (see links below).

www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/4836310/

http://photo.net/learn/dark_noise/

http://www.astropix.com/HTML/J_DIGIT/JPG_DFS.HTM

http://en.wikipedia.org/wiki/Dark-frame_subtraction

[Kevdan]

Thanks for that,

Im now suspecting that it may be due to me(although im blaming the camera) didnt set quality to RAW image so it is in jpeg mode so the detail may have got lost in processingby the camera.

Kev.