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Old 12-07-2011, 04:43 PM
astrospotter (Mark)
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astrospotter is offline
Join Date: Jan 2010
Location: San Jose, CA, USA
Posts: 146
Nice GC report

Fun read Paddy!

Globs to me are up there as nice targets that hold my interest. Your report is very timely in my own quest that started at a 4 day huge star party way up north here. As always I enjoy your reports as they hold lots of goodies and often ones I cannot see up north at +36 degrees.

If and only if you like globs need you read farther ...

What intrigues me about the globulars is the concentration class. They were all rated with DSS plates and so on but visually it is not so easy to squeeze 12 classes of concentration for these GCs for various reasons specific to visual observing. Generally we can say low/medium/high and MAYBE up to 5 classes like that very fine low concentration glob in Musca (N4372 I believe, and I really like that one). We are all tricked visually as we can NEVER see where a glob actually ends. I always judge WAY too small knowing full well that will be the case.

It is even with my 18" dob generally almost impossible to judge the very limits of a glob because the glow fades to nothing. So for concentration class which is required for the next Astronomical League club I am working on I decided to try other ways to visually judge them as I re-observe 50 or more for this club. I am sure I will not get the values right and prior to this I generally rated 'low', medium, high or in cases such as that very low concentrated one in Musca 'very low'.

At the star party in 1st week of July I covered 22 globs (among other things) and decided to try to note things using this method and then judge these numbers using stated GC total size and see if I can find a connection to concentration class they are rated at in books.

Here is the plan:
1) Use 9mmNag, 216x, and judge outer limits of the glow. Also discuss a 'guess' at class and then note any distinct features such as 'streamers'.
2) Use 3.5mmNag, 555x (yes it's close to insane but I am judging glow now and not so much resolution). For this I try to estimate 'covered core' which is where there is full coverage with no dark non-star gaps. I use 3.5mm to get better diameter measurement but seeing was really nice so I felt it was ok for this measurement.
3) Also with 3.5mm 555x measure 'mid-glob boundry' which is where you can say for sure you are about at 50% star coverage with lots of dark spots and stars about 50/50.

I hope to try to correlate this to real measurements but I have little faith.

Thanks for the real interesting read on the south globs I cannot see well from up here Paddy. I always enjoy your ORs, nicely done.

Mark (from the North)
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