Time to bag my first galaxy

BruceG (Bruce) · #1 23-06-2014, 10:15 PM

Had to jump outside last night after wasting all Saturday night waiting for the clouds to disappear (they didn't).
Quickly set up and got things underway by just before 10pm (bad idea with work next day). Got 35 subs of 2 minutes and took 15 darks. I haven't bothered with bias and flats until I gain more practice with the basics.
The result of the first stack revealed field rotation so my PA needs to be more accurate. The PHD graph wasn't real pretty either but hey, let's push on. Tonight I re stacked with 2 reference points to correct the field rotation and I am happy with the result.
Full res available here: http://www.astrobin.com/103549/B/
As always criticism and constructive comments are welcome.
Bruce.

raymo · #2 23-06-2014, 11:42 PM

Very nice Bruce. The only comment I have is that 5128 is not
Aquamarine, and if you look carefully, the whole image has a very faint
greenish tinge. Remove the tinge, and I expect 5128 would look less
aquamarine too.
cheers raymo

BruceG (Bruce) · #3 23-06-2014, 11:46 PM

Thanks Raymo, will make the colour alterations and repost. Thanks for the advice

cometcatcher (Kevin) · #4 23-06-2014, 11:54 PM

That's good for a first galaxy pic.

Going to try for Cent A in the coming nights myself, clouds / fog permitting.

BruceG (Bruce) · #5 23-06-2014, 11:58 PM

This better ? I think so - thanks Raymo

5ash (Philip) · #6 24-06-2014, 08:27 AM

Nice detail coming out , sky looks too black and galaxy looks distinctly oval.
Regards philip

BruceG (Bruce) · #7 24-06-2014, 04:05 PM

Thanks 5ash, I'm guilty as charged. Trying to pull too much out of not enough data. I thought I was capturing some of the galactic glow which is where the elongated or oval shape is coming from.
The good thing about these fora are the lessons one can learn, not just the praise, but where improvements can be made.
Cheers,
Bruce.

cometcatcher (Kevin) · #8 24-06-2014, 05:03 PM

I think that galaxy actually does have an oval glow doesn't it?

RE: The processing. Yes it can be difficult knowing when to stop, how much is too much or too little. Basically, the more (good) data you have, the more you can stretch or process the image. Even with a lot of good data, one has to be careful not to over process certain aspects of the image.

Depends on object type too. Comet photography is a little different from regular deep sky. Most comets pics are deliberately over processed to bring out the faint tail structure. Mega data is never available for comets due to tail motion. At most an hour or two.

Another consideration is image size and if you want to print it out. A small image for forums like this one, the data can be squeezed harder and no one will notice the difference. But if you want to "pixel peep" it at high resolution, put up a full res image or do really big prints, the job is much more demanding on taking and processing the image.

andyc (Andy) · #9 24-06-2014, 08:23 PM

Lovely photo! I also think the galaxy is actually a little oval along that axis - have a look at the super-deep images by Rolf or Mike in the main image forum

LightningNZ (Cam) · #10 24-06-2014, 11:09 PM

Hi Bruce. All in all, I think you've done really well. The image doesn't appear to need flats.

The galaxy IS oval. Most galaxies look pretty weird in one way or another. Now if the stars were oval there'd be a problem... but they aren't.

Do try to resist the temptation to make the sky black. It isn't.

You could probably increase the colour vibrancy a bit more to bring more colour back into the stars.

Cheers,
Cam

BruceG (Bruce) · #11 24-06-2014, 11:34 PM

Thanks Kevin, Andy & Cam for your input. I will take everything on board and have another crack with the processing on this one.
Note to self- spend some time getting better polar alignment next night out as even these short 2 minute subs gave field rotation during the 70 minutes of lights. I had to de rotate during stacking to get rid of star trails in the corners.
Thanks again all for the advice. I appreciate it.
Bruce.

LightningNZ (Cam) · #12 25-06-2014, 03:16 PM

What did you stack with? DSS will auto-rotate the image for you. It just can't fix it if the sub goes too long.
-Cam

BruceG (Bruce) · #13 25-06-2014, 05:21 PM

I use Nebulosity 3 for pre processing and stacking. After I have stacked, I use StarTools and then touch up with Gimp.
I have never used DSS.
Bruce.