Galaxy Hunting - An image of M81... Finally. Much still to learn!

[PhotoGav]

Here is my first galaxy image with the recently acquired Celestron 8" EdgeHD and 0.7x reducer:

19 x 360s subs, calibrated with darks, flats & bias.

This has taken me several attempts, from fumbling around not even able to find the damn thing to struggling with guiding. So it is a great relief to actually produce an image at long last. However, it is far from the image that I had in mind to be able to make!

It lacks colour - is this due to sub length? Ideally I would like to be able to get 600s subs, but guiding isn't up to it yet... I'm working on it!

The stars in the lower right hand quadrant are elongated. Why? Could this be mirror flop? I realised at the end of the session that I hadn't tightened the two mirror locks.... Doh.

There is a nasty gradient. Could this be due to moonlight? The subs were acquired on 8th March, so first quarter moon.

There are still quite a few artifact marks in the image - I shot plenty of flats (49), but they haven't totally sorted things out. Why would that be?

All comments, advice and thoughts most welcome.

[Pete Presland]

it looks like quite a nice image, in the making. very nicely captured.

but you are well off with the processing. all the stars have a grey halo around them which is similar colour to M81 which also should not look that. i am no expert, but it looks like it been stretched to much in "curves" and maybe you can improve the colour using the saturation. like i said i am no processing expert, but i think you have the basis for a good image, just stread carefully with the processing.

[PhotoGav]

Thank you Pete. Yes, I fear you are right, I may have been a bit bold with my stretching, keen to get as much out of it as possible and just going too far. I will attempt a re-process when I can...

[wxsatuser]

Think you have the makings of something good, it's only a matter of processing.

[Knight of Clear Skies]

The galaxy itself has come out very well, I can make out dust lanes almost all the way to the core. There are some odd shaped stars on the right, but you can always crop them out.

[Eddy_]

Looks great to me, thanks for posting.

[Langy]

Nice image!

[glowingturnip]

i found it quite hard to get much colour out of it too, maybe it's just not a very colourful galaxy.  I think the images you see with flashes of red in the middle are shot with Ha ?

My attempt here is saturated almost as much as I could go and still only got a hint of blue out of one of the arms.  Couldn't find any red.

http://stargazerslounge.com/topic/210160-better-late-than-never-another-m81-m82-supernova/

And I hate to say it, but half a frame to the right and you'd have had M82 too 

You've got good detail though, so another run through processing and I think you should be able to get something better out of it.

[Russe]

Very nice image already!

Why don't you upload a stacked version to dropbox and let us have a play with the data? I think the biggest part in producing nice images is in the post processing. Which is A PAIN TO LEARN...

Is this done with the Celestron 8"? Elongated stars - mhm - could be coma. Not sure, whether in that scope you'd better need a coma corrector. Somebody will be along with better advice hopefully!

[Christopher Davenport]

Very nice image Gav.

I am sure there is more in there than what is coming out, some of the expert processing skills on here will help.

What is the focal length on your 8in once the reducer is on?

I think it is 1300 so at F6.5 you should be getting a lot with 6 minute subs.

BTW: Congrats on 6 minutes subs at 1300, it ain't easy.

[PhotoGav]

Thank you for all the comments. That is a great encouragement and keys me up to get out and do better when the dark skies return.

Yes, shot with the 8" EdgeHD & 0.7x reducer, giving a focal length of 1422mm at f7. The edge shouldn't need a coma corrector as it has one in it already... So not quite sure why I have the elongated stars in that bottom right corner?

As for sub length, I am aiming for 600s, but it is a battle to get that long with the current set up without something going wrong! I was pleased to get 360s this time. I will be working on extending the guiding time.

I will upload the stacked tiff file when I have the computer on. It would be very interesting to see what others can do with the raw data.

Clear skies!

[PhotoGav]

Morning All,

I have put the stacked tiff in dropbox for anyone interested and brave enough to download and have a fiddle with:

https://www.dropbox.com/s/l962hpc1k9r2ta5/M81-03-Stacked.tif

Many thanks in advance and I look forward to seeing how people might get on with this data....