M71 Globular Cluster (RGB) - 17 Sept 2019

[geoflewis]

I settled on imaging this cluster as the full Moon made the sky to bright for me to shoot any faint targets in RGB. It is just 9x120sec subs for each of RGB, so just under 1 hour total integration. The data was captured with my QSI583wsg camera through my classic C14+Optec telecompressor lens for an effective F7.

Despite the very bright sky it turned out quite nice with good star colours. I think that it makes quite a striking view, being located amongst the rich star field of the Milky Way.

I hope that you like it and thanks for looking.

Geof

[kirkster501]

Well done Geof, looks lovely.  Quite a handful at that focal length!

[JamesF]

Very nice.  Interesting that the star colours in the cluster appear mostly yellow.  Many of the globs I've imaged have been mainly blue/white.

I must get back into imaging clusters and globs again.

James

[geoflewis]

11 minutes ago, JamesF said:

Very nice.  Interesting that the star colours in the cluster appear mostly yellow.  Many of the globs I've imaged have been mainly blue/white.

I must get back into imaging clusters and globs again.

James

Thanks James, I know what you mean as most of the brighter clusters I've imaged tend to be dominated by blue stars, e.g M2, M3, M13, M15,, etc. I did find this reference from an article on M71 in 'Universe Today', from Nov 2018....

'In NGC 6838 the giant stars are red and become bluer with decreasing brightness.....',

....hence I'm fairly confident that I got a true representation of the star colours in my image.

Cheers, Geof

[Star101]

Very nice image Geof.

 

Edited September 19, 2019 by Star101

[geoflewis]

16 minutes ago, kirkster501 said:

Well done Geof, looks lovely.  Quite a handful at that focal length!

Thanks Steve,

Yes, it is a handful, but the AP1200 doesn't break a sweat with the C14 and (fingers crossed) I'm gaining confidence in the settings I'm using in PHD2 for guiding. I also used SGP's focus target tool for the first time as I've consitently found that using autofocus on target for globulars just isn't reliable. The focus tool requires manual intervent so hardly automatic; I had to stop guiding, slew to a focus target, run autofocus, then slew back, resart guiding and resume the sequence, but it definitely gives better focus than what I'd been doing focusing on the cluster itself. FYI below is a screenshot of PHD2 guide log analysis for just the red filter.

Total RMS after excluding the dithers was sub 0.5", with RA 0.27"and Dec 0.35", being similar for all 3 filters.

Cheers, Geof

[geoflewis]

7 minutes ago, Star101 said:

Very nice image Geof.

 

Many thanks, Geof