M13 in Hercules despite the full moon

[iamjulian]

My fifth Messier, M13 (thanks for the recommendations).

I was planning to head out to my dark spot to chase 3 Juno, but a mix of scattered cloud and a full moon made me change my plans. So I set up on the patio and waited for my neighbours to turn out their lights. Just one small problem - it wasn't the neighbour's lights, it was the moon. The place was lit up like it was still daylight. I've seen bright moons before, obviously, but last night is seemed about as bright as I can ever remember it. Maybe just becuase I wanted it to be dark. I thought about chaning my plans and making it a moon observing night but decided I quite like my retinas.

Fortunately it soon made its way south, the house shielding me from the worst of the light. The sky around Pisces was a mess though so there was no way I was going to find 3 Juno. So plan B was grab a look at M13 before a big bank of cloud rolled in from the West.

Midweek I swapped my cross hair magnifying finder for my red dot finder but it was so light that I didn't even need to switch it on! I just looked through the finder without the dot. My star maps were indoors, so I just had to guess. I thought it was roughly mid way between Sophian and Rutilicus in Hercules so I started hunting in that general area. Took about fifteen minutes, largely because when I found it, it wasn't anything like I expected. I was looking for one or two bright stars, with much fainter stars in the background. It actually looked like the other DSOs I had seen - a faint fuzzy. Time to move up from 30x magnification. On the highest magnification I have, 150x with the 10mm and 2x barlow, it was just possible to see a lot of sharp pin pricks of light, but only with averted vision.

One thing I didn't think to try was refocusing. Would it make any difference? Just thinking the focus may be slightly different. Kicked myself this morning for not thinking of trying the focus at the time.

Nonetheless I was very happy with that. I now know where it is now, plus it must have been about the worst conditions for seeing. The moon washing out everything, including any chance my eyes had of getting dark adapted. I'm sure the next time I see it will be so much better. Ten minutes later the cloud stopped play so I had to go inside and check how my plum liquor is developing - should mature just in time for those cold winter nights

[Vega]

Hi Julian

The big full moon would completely destroy the fine detail you can get. Even though it was out of direct view in your case, the full moon still illuminates the sky until it is well below the horizon. Nice one for finding it though, another one in the bag :-D

Matt

[iamjulian]

Thanks Matt, yes I suspected as much. It was a great night for learning a few more constellations. Anything below about Mg 3.5 wasn't visible making them easier to spot. Don't get me wrong, I love it when it is properly dark, but it makes finding everything that bit harder. I plan to learn proper polar aligning and setting circles in the next week or two.

[mike.brightmore]

Its always best to check the focus after any eyepiece or filter change. Also a Moon Filter is a real help for lunar obs - which is pretty much all you can do, and well worth doing, when the moon is around full.

[iamjulian]

Sage advice Mike. I had the focus right for the stars but then when I landed on M13, I wonder whether the view would have improved any with a further focus tweak. Probably not, but I forgot to try.

Yes, I have a moon filter, but still really bright.

[mike.brightmore]

You can get variable polarising filters which allow you to make it as dark as you want.

[Casus belli]

Its always worth re-visiting M13. One night during the best viewing conditions I have ever seen it was absoultely stunning with a sprinkling of blue and yellow stars, At the time I was rather mysified about the blue stars as I knew that globular clusters tend to be ancient and blue stars tend to be young. I thought I had been imagining things. A trawl through the net solved the problem. Apparently there are quite a lot of star mergers which create blue stars