Sculptor Galaxy

[BruceG]

Looks like no world record stargazing for me tonight - with cloud cover and choking smoke from hazard reduction burning so...... here's something I prepared earlier (last Friday night).
47 subs passed muster after collecting 60 x 2 minute subs, so the result is 94 minutes integration at 1600 ISO on the unmodified 1000D.
I left the reducer / flattener out of the optical chain to get some more image scale.

It's early in the season for Sculptor, so I hope to add to this in the coming weeks.

Hi res here (http://www.astrobin.com/202672/)

[Somnium]

Nice Bruce, I would be interested to see how additional data will help to smooth out the transition of the galaxy to the background.

[raymo]

Very nice Bruce, and I imagine it will improve with more data as the year
wears on.
raymo

[Camelopardalis]

Looks great Bruce :thumbsup: lots of detail in there!

[BruceG]

Thanks Aiden and Raymo, Yes the transition from galaxy interface to the background is very grainy. I used dither when guiding to lower noise but it is the edges that need more data.

Thanks Dunk, it had more detail than the effort I made last year mainly because I am much more fussy about selecting and rejecting subs.

Dithering with my setup really adds to the time needed to collect subs (seems to add 90 to 120 seconds per sub). I guess I should be using a LP filter and taking much longer subs to reduce the number of dithers.
Bruce.

[5ash]

Very nice detail and colours in the galaxy , but what's going on with the stars at the edge of the field of view ? They appear to be elongated as if they are rotating about the centre of the field of view. Stars in the centre are nice and round.


Regards philip:question:

[BruceG]

I have removed the field flattener / reducer maybe this is effecting the areas way from the centre? Anyone else have any clues?

[raymo]

It looks like field rotation, what mount are you using?
raymo

[BruceG]

Hi Raymo,
It's my HEQ5 guided. PA is pretty good but I can see why you think it's field rotation. I guess the only way to prove it is the mount is to try the same subs with the reducer flattener in place and see if I stll have the same issue.

[raymo]

Your HEQ5 won't give you field rotation; I thought you might have been using an alt/az mount. I know little about reducers/ flatteners, so can't help there. Try an exposure without it; if it goes away you know the reducer is the culprit in some way or another.
It just occurred to me; is it possible that the camera turned a bit during an exposure? Worth looking at the individual frames to see if it appears on one or all of them.
raymo

[BruceG]

Good point Raymo, I will take a look at the individual subs. When I vet them, I am always inspecting the main subject area, not the edges.
Cheers,
Bruce.