An Autumn Grab Bag

Overall the past 4+ months have not been kind to amateur astronomers in my area. There seemed to be an above average number of cloudy evenings, and those that were clear often had a haze triggered by smoke drifting down from Canadian wildfires. So to say that the return of some cooler, crisp fall evenings was most welcome is probably an understatement. 

Jupiter and Saturn took some of my attention, but I also made time to check in on some targets among the Astronomical League's Urban List in my ongoing assessment of how easily they can be spotted from suburban skies that suffer from significant light pollution.

August 19, 2023 
Sky: Mostly clear, temps ~65° F, light winds
Transparency: 7/10    
Seeing: 5/10
Limiting Magnitude: 3.2

NGC 6818 
Planetary Nebula in Sagittarius
10” f/6 Newt   15mm Plossl  CGX-L Mount  

It took a 4-star alignment process to get the mount's GoTo working accurately enough to ensure that it was landing on targets with good accuracy, but that was a prerequisite given the light pollution in the southeast where my chosen target lies. But it was worth it, as once I peered into the 25mm eyepiece it was apparent as a small, uniformly round orb with perhaps a slight blue tint to it amid a handful of field stars. Popping in the 15mm enhanced the view of the planetary. There was no structure such as an annulus that I could discern, and it sported an even distribution of light. While a little faint, it bore direct vision well, even without a UHC filter. Alternating between direct and indirect vision yielded no evidence of the central star.

NGC 6934
Globular Cluster in Delphinus
10” f/6 Newt   15mm Plossl  CGX-L Mount  

I know that I have seen this DSO before with my 6” RV-6, but that observation is lost among the many that have gone by the wayside. I wish I had been better about archiving them for later access.

When inspecting the field with the 42mm once the scope completed its slew there was no sign of the globular. I did not tarry long before switching to the 25mm eyepiece with the Baader Moon & Skyglow filter, which revealed it immediately. I followed up with the 15mm which gave a good view of this globular. The field has stars that form roughly an “arrow” asterism pointing to the east. And the globular lies along the shaft of the arrow on the side closest to its apex. It is perhaps 4-5’ in size and can take direct vision but is improved with averted. No resolution of the member stars was noted. The globular is circular and has surprisingly even illumination – no sign of a brighter core discerned in the observation this evening.

September 3, 2023 
Sky: Thin haze, temps ~85° F, calm
Transparency: 7/10    
Seeing: 7/10
Limiting Magnitude: 3.2

IC 4756
Open Cluster in Ophiuchus
6” f/8 Newt  TV 25mm Plossl  HEM27 Mount

Once I verified the HEM27 was working well I decided to target this open cluster. I slewed to Rasalhague and then did a center operation to ensure the hop over to the cluster would be on target. And indeed, as soon as I peered in the eyepiece with the 42mm I could see a loose, large cluster of stars.

Bumping the magnification up to the 25mm came close to filling the field, implying the cluster size at about ¾ degree. There is one bright anchor star, perhaps 7^th or 6^th magnitude, in the south of the cluster – no color noted in it or any of the other members of this cluster. The other members range in brightness from about 8^th magnitude down to limit of visibility. All told about 40 stars are seen, but there is no nebulosity hinting at any mass of unresolved members. Very nice cluster and would be worth checking again under darker skies.

NGC 6709
Open Cluster in Aquila
6” f/8 Newt  8mm TMB  HEM27 Mount

Once the scope finished its slew I checked the area with the 25mm TeleVue Plossl, and my attention was drawn quickly to an eye-catching triple set of stars. West of it seemed to have a slightly above average number of stars, but nothing that screamed “I’m a cluster”!

Dropping in the 8mm TMB I see a few more stars and a dim fourth sun joins that pretty trio. I do a quick online check to verify that I am on the cluster, easily confirmed by the trio-plus-one showpiece of the field. As my night vision adapts, I see perhaps about 15 stars that may be cluster members in what is a coarse and not very rich offering. No hints of any nebulosity, and none of the stars depart from the standard white color. It is small, perhaps 10-15’ in size. While it may be really nice in darker skies, I'd be inclined to drop this one from the Urban List.