Date: 1st October 2011
Conditions: Cloudless, dewy (88% humidity), some mist. Hazy. Warm, about 16°C (61°F). Lots of owl activity (Barn Owls and Little Owls mostly) plus the intermittent ‘pop’ of acorns falling from the oak trees.
Seeing: II (Good)
Transparency: III (Average)
NELM: 6.0
Equipment: 18″ f/4.3 Dob, 22mm Televue Panoptic (90x), 8mm Televue Radian (247x)
The early autumn heatwave continues, with hot days and clear nights. However, there has been a downside, high humidity leading to formation of mist and fog at night with masses of dew, and Thursday night (29th September) ended up as an ‘eye candy-only’ session and an early finish. I did, however, compare my 18 inch and 12 inch (now sold) scopes side by side, with eyepieces of comparable local length (20 and 22mm) and quality on M13 and the difference was even bigger than I expected, with the 18 inch absolutely blowing the 12 inch out of the water in detail seen. I could see the propeller feature quite easily in the 18 inch but not very easily in the 12 inch. If you look at Obsession’s M13 comparison chart (scroll down the page), it shows the difference between a 12 inch (12.5 inch in the example) and an 18 inch but in real life, the difference was even more apparent.
Back to last night (I’d not bothered observing on the 30th, simply because the mist was so bad that deep sky observing would have been a dead loss) and I’d lined up some galaxies in Pegasus, Pisces and Triangulum to observe. Last night’s conditions weren’t great but an improvement on the previous night. I’ve made an addition to the telescope in the form of black plastic dustbin bags taped over the shroud, this is in an effort to keep the shroud from getting soaked with dew. A wet shroud isn’t nice but the water dripping on to the primary mirror is even less nice – but the garbage bags did their job. Garbage sacks aren’t exactly pretty but who cares in the dark – and it’s better than water marks on the mirror!
I used what has become my favourite eyepiece combination with the 18 inch, my 22mm Televue Panoptic and 8mm Televue Radian.
NGC 7479, galaxy in Pegasus – Large, fairly bright galaxy elongated north-south. It has a diffuse halo with some brightening towards the centre. There is a star on the northern end, plus a fainter one on the western side. Looks mottled. This galaxy has spiral arms which should be visible in the 18 inch but, because of the high humidity and hazy conditions, I didn’t see them. One for a better night. 90x, 247x.
NGC 7626, galaxy in Pisces – Forms a bright pair with NGC 7619. Both galaxies, part of the Pegasus 1 galaxy group, are easily found at 90x. Elliptical with bright core and non-stellar nucleus. Oval, elongated SW-NE. 90x, 247x
NGC 7619, galaxy in Pisces – Very similar to 7626 this also is oval, elongated SW-NE and has a bright core with a non-stellar nucleus. It is slightly brighter than 7626 and the core is also brighter. 90x, 247x
NGC 7617, galaxy in Pisces – Much fainter and smaller than 7626 and 7619 this is a tiny oval glow just to the SW of 7619. Brightens slightly towards the core. Not seen at low power (90x). 247x
NGC 7541, galaxy in Pisces – Easily found at low power (90x) this is a bright spindle elongated 3:1 west-east which stands out well against the background sky, despite its lowish altitude and the murk. It’s fairly featureless, with no sign of becoming any brighter towards its middle. 90x, 247x
NGC 7537, galaxy in Pisces – This lies immediately to the south of 7541 and is smaller and fainter. It is elongated SW-NE. Not seen at low power but easily seen at 247x.
NGC 7785, galaxy in Pegasus – An obvious, bright galaxy set among a triangle of stars. Fairly small and elongated NW-SE. It has a fairly bright centre and a non-stellar core. 90x, 247x
NGC 7742, galaxy in Pegasus – Bright and obvious at 90x. At 247x, it has a round halo with a bright centre and non-stellar nucleus. 90x, 247x
By this time my secondary had dewed up badly and my Telrad, despite the dew shield, had become almost unusable so I packed up, my planned assault on Triangulum will have to wait until another time. It had got to the point where I couldn’t see any galaxies and the brighter stars all sported fetching halos. I am going to be investing in a dew prevention system. I have already bought a power supply, I now need a controller and a couple of heaters for the secondary and the Telrad.
I have sprung for a Telegizmos scope cover from the Widescreen Centre. It’s expensive (too expensive) but it will help keep dust and other crap off of the scope and mirrors. As I have sold my 12 inch, I now have more room in the shed for the 18 inch and I can keep it assembled, so it can just be wheeled in and out each session. The assembled scope, with wheelbarrow handles attached, fits into the shed with a tiny bit of room to spare. At present, the primary is protected by a chamois leather (as recommended by David Lukehurst) and the plywood cover, while the shroud (and bin liners!) is kept on and a sheet thrown over the top to prevent stuff getting onto the secondary, but the Telegizmos cover will give it proper protection.
Sketches will follow once I have scanned them.