NGC 247 and some friends

lazjen (Chris) · #1 03-10-2016, 01:00 PM

From the backyard, this was a difficult target to get a decent guide star so that the galaxy was well framed. In fact, I didn't get close to decent framing, so this image is heavily cropped.

This was taken with the ASI1600MM-C camera, "Unity" setting.
L: 75 x 60sec
R: 75 x 60sec
G: 72 x 60sec
B: 68 x 60sec

60 second images were probably too short, but I was concerned about the LP impact. I probably should go to a lower gain setting for this target.

Again, no flats. I can see I will have to sort this out as I think the dust donuts made this image harder to process overall.

Click image for larger version

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Another version, probably not much better resolution: https://flic.kr/p/LSqHrS

There are 3 other galaxies in the image that I can see, but I haven't been able to work out any identification for them.

Comments, constructive feedback, etc, welcome.

renormalised (Carl) · #2 03-10-2016, 01:08 PM

Getting there. Just needs those darks and flats. Might do to give the sensor and/or glass window on the camera a bit of a clean. See how some more subs turn out before you up the sub length. Looks like you have a bit of a colour gradient there as well. That should clean up alright with the darks and flats added, but if it's still there, it can be removed. It'd look a lot better if you could get to a darker site and try the same target there.

lazjen (Chris) · #3 03-10-2016, 01:13 PM

Thanks. I should have mentioned I did use darks - just no flats.

strongmanmike (Michael) · #4 03-10-2016, 06:32 PM

Doesn't look too bad Chris, just needs those flats really. This is one of the few galaxies that shows good resolution into stars. Those two galaxies are part of Burbidge's Chain. If you have a big enough field it's cool to try and frame them with the main galaxy

lazjen (Chris) · #5 03-10-2016, 07:10 PM

Thanks Mike. So, if I understand correctly, there's 2 more galaxies to the "left" of my image? If so I think could easily get them with the main galaxy - assuming I can get a guide star in the right place. Maybe not in the backyard, but a dark site it should be possible.

I just "found" your NGC 247: http://www.pbase.com/strongmanmike2002/image/157929594 framed as you suggest. Nice! I can see my pic is "upside down" to your pic.

I've been told that the 3 small galaxies are (also) known as (left to right in image): PGC -2794, PGC -2796, PGC -2795.

strongmanmike (Michael) · #6 03-10-2016, 07:18 PM

Quote:

Originally Posted by lazjen

Thanks Mike. So, if I understand correctly, there's 2 more galaxies to the "left" of my image? If so I think could easily get them with the main galaxy - assuming I can get a guide star in the right place. Maybe not in the backyard, but a dark site it should be possible.

I just "found" your NGC 247: http://www.pbase.com/strongmanmike2002/image/157929594 framed as you suggest. Nice! I can see my pic is "upside down" to your pic.

I've been told that the 3 small galaxies are (also) known as (left to right in image): PGC -2794, PGC -2796, PGC -2795.

Yes I recon it makes for a special framing really and worth doing if you can from a good site...then you can see the real scene

Good luck...and get those flats!

Mike

lazjen (Chris) · #7 03-10-2016, 07:23 PM

You've got some good gear there - excellent "processing"

DJScotty (Scott) · #8 03-10-2016, 08:16 PM

That's a nice little image.
Yes i will say flats will help.
What is your guiding setup?

lazjen (Chris) · #9 03-10-2016, 10:06 PM

I use an OAG with an Sbig ST-i (colour, unfortunately). I like the ST-i (darks are easy to create with its shutter), but I regret not getting the mono version now.

The OAG limited field of view at times makes it difficult to find guide stars.

Atmos (Colin) · #10 03-10-2016, 10:19 PM

Considering that it has been captured with light pollution, it's turned out quite nicely. From what I have read over on the CN threads, a Gain of ~75 may be a good place start.

lazjen (Chris) · #11 03-10-2016, 10:35 PM

Thanks Colin. Yes, I've been reading a few threads over on CN, including the mention of 75 - 77 gain (I think that was with a 10 - 12 offset?).

Picking the right settings for this camera is going to be a journey in itself, however for this target dropping the gain to 75 - 77 should allow for longer exposures. That will drop my quantity of exposures but I should still be getting enough for PixInsight to do its magic.

*****
I did some tweaks to the setup this afternoon, including cleaning the reducer and the glass on the front of the camera. There was an obvious spec there too. Tomorrow night is looking to be clear so I hope to do more testing then.

RickS (Rick) · #12 04-10-2016, 04:02 PM

Should look good with flats applied, Chris

lazjen (Chris) · #13 04-10-2016, 11:03 PM

Thanks Rick.

I did manage to do some testing tonight and I think I've minimised the vignetting. I'm not sure if I can do much better given I'm using 1.25" filters. If I got a custom connector, I think I'd be able to get the camera closer to the filters.