I hauled the 18″ out for some summer observing. Because it doesn’t get properly dark here at this time of year, I decided to go for some planetary nebulae as these are good targets for the less-than-dark skies.
Date: 8/9 July 2013
Conditions: Very mild (14°C/57°F), 74% humidity but minimal dew.
Seeing: Good; Transparency: Good, improving to very good later.
Instrument: 18″ (457mm) f/4.3 Dobsonian with 22mm TeleVue Panoptic (90x); 12mm TeleVue Nagler (165x); 9mm TeleVue Nagler (219x) and 5mm TeleVue Radian (395x)
Oxygen III (OIII) filter
I began with some eye-candy, M57, but the reason for this was that I was having a go at seeing the rather difficult central star from home. I’d seen it from TSP once, with a friend’s 18″, but not seen it from home.
It eventually popped out in moments of good seeing. Pretty faint, but it was there. 395x
NGC 6772, Aquila – This has eluded me in the past but I finally got it tonight. At 90x, it’s invisible without OIII filter but looks like roundish irregular smudge with the filter. At 165x it is only just visible without the filter but with the filter added, it looks like a slightly oval with ragged edges. 90x, 165x
IC 1295, Scutum – Easily found, lying just east of M11. Very faint without the OIII filter but nice and obvious with the filter. At 90x it’s a uniformly oval glow, elongated east-west with a star lying just off the western end.
At 219x, it’s visible without a filter as an oval glow only just brighter than the background sky. The OIII improves the view and the PNe looks a little darker in the centre. 90x, 165x
NGC 6803, Aquila – small, bright and easily found at 90x without the OIII. With the OIII, the PNe looks larger. At 219x it is big and roundish with fuzzy edges. Slightly darker in the middle. 90x, 219x
NGC 6572, Ophiuchus – Easily found, looking like a fat, intensely blue-green star at 90x. At 219x it’s distinctly oval and very turquoise. OIII doesn’t do a lot except make the PNe look a bit larger while 395x shows a definite north-south oval, although at high magnification the colour gets washed out. 90x, 219x.
I also looked at the Veil Nebula, M11 and M27 before packing up at 0100 UT (0200 BST)