Tales from Santa Luce, Tuscany, Episode III: Planetaries Galore!

[michael.h.f.wilkinson]

In this continuing saga of observations from Tuscany, my next session was logged on July 28, 2013. This time I set up the C8 in time to achieve thermal equilibrium, but despite that Saturn looked a bit wobbly. With the day's heat reaching 35 Celsius easily, this was hardly surprising as thermals rose from the countryside. There were moments of stable air, and then the planet looked quite nice. I decided not to use the DMK21 this time, given the very bad seeing (which could only get worse as the planet got nearer the horizon.

I started out to testing the transparency of the skies on the Trifid Nebula (M20, always one of the slightly shy Messier nebulae). The emission component could be made out OK, especially with the UHC filter in place, but the northern reflection component was all but invisible (without UHC, of course). The view was not a patch on the glorious views I had from near Cahors last year. Even the Lagoon (M8) looked less bright than I had expected. Some high haze seemed to be affecting the views.

Not to be deterred, I decided to hunt for some planetary nebulae that had escaped me last year (or I had simply overlooked on the chart). Most of these are near stellar, and are very hard to distinguish from stars. This does mean their surface brightness is huge compared to most other emission nebulae.

This time round I was better prepared for these little PNs, having purchased a second-hand Denkmeier Filter-Switch Diagonal some time ago. This allows me to switch UHC or O-III filters in and out of the optical path rapidly. PNs retain their brightness while stars fade when such a filter is switched into the optical path. Last year I would have to remove the EP, screw in the filter, and try to remember which star was brighter than which. That works in sparse star fields, but in the heart of the Milky Way it is hopeless. "The Denk", as I tend to call it, is a brilliant tool for this kind of search. Now I just operate a slider back and forth, as I keep my eye to the EP. The only drawback is that it will not come to focus with my 80mm F/6 refractor. In the C8, there are no such problems.

First target was NGC 6567, near mu Sagittarii. Tiny, practically stellar (certainly in the poor seeing), "UHC-blinking", as I like to call the method, was the only way to pick it up.

Near the western end of M24, but still within the star cloud, I found NGC 6567, one of the 100 brightest planetaries. Similar to the above, but a touch brighter.

I checked out Antares, but the disco was in full swing, so no hope of splitting.

M19 was up next; slightly underrated in my view, it is a very nice globular. This time is was a stepping stone to NGC 6284, which is an altogether smaller globular, a friend from last year, and this time a staging post to IC 4634. This again was a stellar planetary, and also on the list of 100 brightest planetaries. After verifying the position a couple of times, I moved over to M22. Really superb, and a short hop to NGC 6644 (also on the list of 100 brightest planetaries). This is a very tricky one indeed. I have a feeling its central star is contributing more continuum, reducing the UHC-blink effect. Still, after several filter-switches, I noted that one star seemed to brighten relative to three very similar stars when the UHC filter was in. A look at Carte-du-Ciel confirmed the identification.

The last new object was IC 4732. This proved even harder, but the filter-switch did it again. None of these objects are particularly difficult to see, but identifying which speck is which is the hard bit.

Just to have a look at a really impressive planetary, I had a look at the Ring Nebula (M57). Awesome as ever.

M51 was very nice despite the distant glow of Livorno and Pisa.

I tried one more slightly off-the-wall object: Pal 8. This is a globular cluster found on the Palomar list (just 15). They are considered real tests for imagers, but I tried to spot it nonetheless. No luck, unsurprisingly.

No shame in the single failure, what with 5 new planetaries bagged, and many old friends revisited.

Next episode: Globulars, loads of globulars.

[cotterless45]

Lovely report , few more targets to look at .Definately worth travelling around, thanks for posting,

Nick.

[Double Kick Drum]

Thanks for sharing episode III. I haven't seen the Triffid for such a long time. A lovely photographic object.