M15

[Kevin Phillips]

Hello everyone. Last night had a stab at M15 Globular cluster, came out alright in the end. 3 mins exposure and manage to squeeze in 40 frames before the birds woke up.

Had some issue with guiding. See to pretty much resolved it. 

It looks as if one of the tripod legs keep sliding down only a fraction but it was enough to push the RA out by miles, phd2 was struggling to keep the RA on track. I did the polar align again, it was way off. Once I started to guide for the second time it was much better but still needs improvement, another thing on phd2 I had contrast so high I was unable to see if the stars in phd2 was sharp enough, so this also did not help with guiding issues. Thanks to Tony has given me an idea on preventing further issues of tripod legs slipping.. all in all I am happy how M15 turned out.

Kevin P

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[JR]

Kevin

That's a very appealing image, regardless of the technical problems.  Considering the tripod was shifting and the polar was alignment going, it's remarkably good.

James

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On 5 Jul 2022, at 17:36, Kevin Phillips <thewels...@live.com> wrote:



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[Kevin Phillips]

Hi James

I manage to correct the alignment and thus guiding was a lot better to capture M15.

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From: 'JR' via croydonastro <croydo...@googlegroups.com>
Sent: Tuesday, July 5, 2022 8:52:10 PM
To: croydo...@googlegroups.com <croydo...@googlegroups.com>
Subject: Re: [croydonastro - 7336] M15

 

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[tcos...@gmail.com]

Hi Kevin

That’s a very nice image with lots of colour saturation and good focussing. You seem to be really nailing these globular clusters this summer! I see that tracking was a bit of an issue because of your mount/tripod. Nevertheless  I think you get excellent results from a portable setup and well done for the dedication to stick at it.

Kind regards

Tim C

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[William Bottaci]

Hello Kevin, not at all bad, it's come out pretty good.

Star colours too, from blue-white to orangey; spices up the field.
The stars show the very minimum of trailing, and considering each exposure is of 3 minutes clearly PHD2 guiding is working, but it is capable of better. I would have guessed differential flexure (dangling cables, loose or flimsy guidescope mounting) but the trail is exactly in line with the RA axis so there's a clue there. Certainly not a polar alignment problem, and I know you do very precise aligning there.
However, sorry to say but this does not mean you don’t have a differential flexure issue.

As is common with globular clusters the centre is bright and it's not surprising that the core is over-exposed, but then Messier 15 is one of the most densely packed globulars in our galaxy, so you're forgiven :).

Easy to find, it's well placed now and for several months; a must see deepsky object and fairly bright so any binoculars will see it but you have to see it through a reasonable telescope and see the myriad of tiny pinpoint stars. This cluster is notable for being one of the oldest, at about 12½ billion years you're probably not going to see anything older. Also at 36,000 lightyears away it's an opportunity to see the furthest stars.

There are at least 2 satellite trails, one going up just to the left, and Deep Sky Stacker should have gotten rid of them completely - well they are mostly removed.

You've captured stars to magnitude 18 easily, and a number of galaxies, of which IC 5115 is easily visible in the far top right corner, at magnitude 15 and 500 lightyears away. I can see at least 4 PGC catalogue galaxies smaller and fainter so quite likely even further away - I got bored looking for more :).

PHD2 has a slider control just before the Brain (it's not a brain, just a button to access more advanced settings) that changes your view of the field. Use it to get the best looking stars to allow you to focus well, which is a must. It does not change what PHD2 sees, which always has a better idea of which guide star(s) to use. Use the green SNR number to the right (41.6 in your case) to see if PHD2 can see well.

A pleasing image to look at, thank you for sharing.
William

[Kevin Phillips]

Thank you for your comments. I didn't know there were so many galaxies in that image.

Kevin

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From: croydo...@googlegroups.com <croydo...@googlegroups.com> on behalf of William Bottaci <w.bo...@gmail.com>
Sent: Friday, August 19, 2022 2:28:20 PM
To: croydo...@googlegroups.com <croydo...@googlegroups.com>
Subject: [croydonastro - 7391] M15

 

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