Category Archives: Supernova

Summer observing

As those of us stuck at high latitudes know (I’m at 50° North), the long twilights of summer aren’t that conducive to deep sky observing. When it does get ‘dark’ it’s only astronomical twilight as the sun is less than 18° below the horizon. But while it may not be good for the really faint fuzzies (and here, I admit that webcam users and imagers have an advantage over us eyeball-only types) it’s still dark enough for the bright DSOs. Even Messiers you’ve seen countless times before are worth repeated looks and, as it is really the only observing you can get during summer at these latitudes, it’s better than nothing.
The good news is that sunsets started to get earlier from July 1st and from the 16th true darkness returns, only for 36 minutes on the first night but the hours of darkness soon get longer. With a reasonable 30-day forecast (‘reasonable’ meaning average for this time of year – warm sunshine, some showers, average/slightly above average temperatures), I should hopefully get in more observing later this month, good news as I am hoping the new 18″ will be finished in around 3-4 weeks’ time.
I did a little observing last night, going after the supernova in M51, which is still on show, and a little open cluster-hunting in northern Cygnus. There are several on the Herschel II list and real little gits they are too. NGC 7031, NGC 7067 and NGC 7082 were on my list as well as the bright nebula NGC 6857. I also took a look at M57, the Ring Nebula in Lyra.

My notes are as sparse as the clusters themselves were!

Date: 2nd July 2011
Conditions: Cloudless, cool (12° C/53.6° F), some dew
Seeing I-II (later)
Transparency: II
NELM: Around 5.5-5.8 due to the astronomical twilight. Definitely less than 6.0. Milky Way visible all the way to Sagittarius but lacking contrast
Equipment: 12″ f/5 Dobsonian; Televue Panoptic 22mm (69x), Televue Radian 8mm (190), Televue Radian 5mm (304x)

SN2011dh in M51 has got a little brighter recently. It was definitely easier to see than last time but that’s probably as much to do with no Moon in the sky as it is to do with the brightness of the supernova – M51’s spiral arms were certainly easier to see this time out. I didn’t make a sketch this time.

NGC 7031, open cluster in Cygnus Small and quite poor. Compressed. 69x, 190x
NGC 7067, open cluster in Cygnus – Faint, adj to 9th mag star. In rich surroundings. 69x
NGC 7082, open cluster in Cygnus – Scattered, large, cluster. In rich area. Not that great and looks more like a richer portion of Milky Way. 69x

I’ll come back to these on a darker night, and the same goes for NGC 6857 which I looked for, a little over-optimistically, but didn’t see. It was at this point, around midnight, that the observing was interrupted by the kids in a house the other side of the footpath putting an insecurity light on, which encroaches on our garden – although it’s worse in winter because of the lack of leaves on the hedge and trees. They’d gone out into the garden do do some camping (I assume they were camping as I heard what sounded like a tent being put up and a tent zipper being opened and closed) and obviously wanted to see what they were doing. I wish they’d used torches though. I decided to pack up, an hour earlier than I’d intended, as the light was a nuisance – and I didn’t want to disturb them with ‘funny noises’ from across the way (it’s strange how loud switching eyepieces and moving around can be in the dark) and, more importantly, I didn’t want them disturbing me!
At least, when I get the new scope, it will be easier to move to another location in the garden, as it will break down and have wheelbarrow handles on it. I’m intending to move my observing spot further down the garden, although the ‘observashed’ will remain where it is, although I can move around depending on where I am looking at the time.
I shoved the 12″ back into the shed and closed the doors on it. This morning, when I went up there to put it away properly, I found I’d left the Telrad switched on. Fortunately, a Telrad reticle uses up hardly any power so the batteries were far from flat. It’s not the first time I’ve left a Telrad on and I guess it won’t be the last!


Collimation’s one of those weird things that has a reputation for being awkward, annoying and downright difficult and it’s viewed almost as being akin to witchcraft, with ‘The Knowledge’ being available to only a select few individuals. However, observers need to know how to collimate their scopes properly in order to get a decent image in the eyepiece and to achieve focus at high magnifications. There’s no real risk of buggering it up as the mirrors, even if they end up miles out of alignment, can easily be put right again. My current scope, a 12″, is a real git when it comes to going out of collimation and I have to fix it before each and every session. I am hoping my new 18″ won’t be as temperamental.
For me, cleaning the mirrors holds far more trepidation than merely aligning the things. That’s where things can really go wrong…I’ve managed to scratch a mirror attempting to clean it in the past.

For those who can’t quite ‘get’ collimation – and in the past I have been among those people – check out the brilliant video tutorial on the website Andy’s Shot Glass, which explains visual and laser collimation, simply and perfectly. Click here to see it. I have no association with Andy or his website but it’s the best and most simple explanation of the process I have ever seen. Just reading about the process doesn’t make it immediately clear and it may take several re-reads in order to make sense of it; seeing it, though, makes it much clearer. There are loads of websites which offer help with collimation, and there are threads about it on Cloudy Nights, but nothing is as helpful as actually seeing something demonstrated such as in the video.
The way to do it (and the best way for a lone observer such as myself) is to use the sighting tube to centre and tilt the secondary mirror, then use a laser collimator to get the beam right into the centre of the primary. Then you go to the back of the scope and adjust the primary mirror itself, getting the beam in the centre of the laser’s display window, meaning everything is centered nicely when you look in the sighting tube again and your collimation is spot on. It’s not hard and takes a couple of minutes. Pure visual collimation without a laser is more awkward, as that requires two of you to perform the procedure, unless you have arms like Mr Tickle, which most people including me, don’t!

Supernova SN2011dh in M51

Despite my knee problem, I decided to get the scope out and look at the supernova in M51. I didn’t want to wait until the knee was better (it’s improving all the time) or until the Moon was out of the way as the supernova might have faded by then and I didn’t want to miss it.

Date: 8th June 2011
Conditions: First quarter Moon, all-night astronomical twilight. Milky Way visible. No dew, breezy.
Seeing: II
Transparency: II
Equipment: 12″ f/5 dob. Televue 22mm Panoptic (69x), Televue 8mm Radian (190x), Televue 5mm Radian (304x) and Televue 3mm Radian (507x)

I observed the supernova under less-than-ideal conditions, thanks to first quarter Moon and the all-night astronomical twilight we’re cursed with at this time of year – and I have certainly seen M51 better than this. However, the Milky Way was visible and the transparency and seeing were both good. The supernova was best seen at medium to high magnifications. It wasn’t immediately obvious but after a minute or two with averted vision, popped into view as an extra star. I made the sketch without a photo to guide me and checked it against a photo of the supernova’s position later.
The best views were at 190x and 304x. The view at 507x was terrible, it was just smeared all over the place.

The supernova is arrowed on the sketch.