Tales from Santa Luce, Tuscany, Episode VI: Of Pisa and Planetaries

[michael.h.f.wilkinson]

August 1 was clear again, after the long session on July 31, so I started off with an early evening solar session. In H-alpha (with the LS35), loads of intricate structures on the surface were notable, but prom activity was less spectacular than it had been previously. White light with the APM 80mm and Herschel wedge showed quite a few sunspots. I then hooked out the 15x70 and had a look at the distant mountains to the north-west. Below the mountains I could see a city with the naked eye, but the 15x70s revealed it was Pisa, as i could make out the Duomo and the Leaning Tower easily, and in pretty good detail. After dinner, when the sun had truly set, I took another look at it, to see how well it was illuminated, but that view was a bit disappointing, as the many city lights obscured the view a bit. I did get a good look at the double cluster, however.

After that, the C8 had reached thermal equilibrium with the balmy night air, and I decided to hunt down some more planetaries.

IC 4634 in Ophiuchus was first, one of the 100 Brightest Planetary Nebulae. It is near stellar (certainly in this seeing), and could be made out fairly easily by switching between UHC and no filter quickly, and observe how it "blinks" with respect to the stars.

IC 4846 in Aquila was similar, also fairly easy, and near stellar (also in the above list)

NGC 6778, also in Aquila, was surprisingly easy, especially because it is not on the Brightest Planetary Nebulae list. What makes it easy is not so much brightness, but the fact that it is resolved.

NGC 6572, which is in the top 100 list, was easier still. It was bright, resolved, and even seemed to show a hint of ring-like structure (a bit elongated).

The next two new ones to hunt down were in Sagitta, so I spent some time admiring M27. Gorgeous sight.

NGC 6886 was another "UHC-blinker", near stellar, and near impossible to find without a filter-slide or similar system to quickly switch filters.

NGC 6879 was similar, but very faint (mag 13), and just as easily mistaken for a star. At that low brightness no real colour can be distinguished, so the UHC filter trick is needed.

Last up was IC 4997, at just 2 seconds of arc according to the list, one of the most compact I spotted. It is close to a star of very similar magnitude, which makes the blinking in UHC quite easy to spot.

After this I packed up the scope, pleased to have found no fewer than seven new planetaries, 6 of them on the Brightest Planetary Nebulae list.

Next episode: First of the Summer Galaxies

[KevUU]

Nice write up again, although that goes without saying with your reports

I hadn't realised that so many of the planetaries are basically stellar - is it really only a handful of M57s and Snowball's that give anything away visually?

[michael.h.f.wilkinson]

Nice write up again, although that goes without saying with your reports

I hadn't realised that so many of the planetaries are basically stellar - is it really only a handful of M57s and Snowball's that give anything away visually?

There are quite a few non-stellar PNs, but a large fraction look like tiny planets with roughly the same colour as Uranus and Neptune. Many non-stellar PN have very low surface brightness (like the Abell Planetaries). These were mainly spotted on Palomar Sky Survey plates, and are very hard visually.