Labours in Hercules

[John]

Sorry about the rather naff re-working of the Greek legend but I could not resist

I had my 12 inch dobsonian out for a couple of hours this evening, when darkness eventually fell.

I spent most of my observing time in Hercules re-visiting the globular clusters and planetary nebulae that I had observed with my 120mm refractor a few nights back.

The constellation was pretty high in the sky so the views of the brighter pair of globular clusters (M 92 and M 13) were pretty spectacular with the much larger aperture. At 338x magnification M 13 takes up around half the field of view and M 92 not much less. Stars resolved right into cores of both clusters.

A bonus that the larger aperture bought to M 13 was a view of the galaxy NGC 6207 around half a degree to the north east which lies 2,000 times further away from us than the grand globular cluster. At 122x magnification both could be seen in the same field of view with the cluster resembling a tight stellar swarm and the galaxy a small, softly glowing oval. Always a "stand out" view for me in Hercules 

The fainter and more distant globular NGC 6229, while not as impressive as it's illustrious neighbours, was easy to see and some faint star resolution was visible in the outer fringes of that one at 199x magnification.

Dropping back down to the area of sky beneath the "keystone" of Hercules, the small but quite bright planetary nebula NGC 6210 was quite easy to pick up and seemed to me to resemble a smaller version of the Cats Eye Nebula (NGC 6543) in Draco. A quick visit to Draco to have a peek at the Cats Eye confirmed this similarity in form if not in apparent size.

I've a busy day tomorrow so could not make this a long session. I did want to try and find something new (to me) in Hercules though and Stellarium suggested that the galaxy NGC 6166 might be possible and well positioned.

Well this distant galaxy was quite hard work to find tonight. Finding the correct spot in the sky was straightforward enough but actually seeing any trace of the galaxy, somewhat harder. Eventually I thought I was getting traces of a faint suspect glow in the right place at 94x magnification. Jumping up to 199x did not really help but a spot in between, at 122x (13mm eyepiece) confirmed the lower power glimpses with a little more conviction. It's surface brightness is around magnitude 12 I think but possibly a little less.

NGC 6166 is one of the more distant galaxies that I've observed - it's distance from us is given as around 490 million light years away. So that was a new object to end this session with 

Well ...... not quite. I could not resist a few minutes gazing at the Ring Nebula in Lyra, which was now well up in the sky and starting to look rather splendid. A future challenge will be to try and spot the central star in this famous planetary nebula, but not tonight. Just, relax, enjoy the views for a while and then time to pack up.

 

 

 

Edited June 1, 2021 by John

[Voyager 3]

Jon as you've mentioned NGC 6210 , I would like to suggest you 3 more small bright planetary nebulae in the upcoming summer skies - NGC 6572 in Ophiuchus , NGC 6818 in Sagittarius and NGC 7009 in Aquarius . You may have observed all of them but still .

 Actually they 4 are in my SkySafari observing list , but the weather here is exactly opposite to what someone would like ... I forgot what criteria I've filtered them . But I'm pretty they all have very high surface brightness , especially NGC 6572 . SkySafari says it has 100 times the surface brightness of M57 ! If someone can find them and give a report I will be very much pleased !