17 May 2010

Sketch from Mansfield

I don't know how he managed it, since I was shivering too much to be able to hold a pencil...

16 May 2010

Mansfield nights #2

While we were setting the scopes up - before it got dark - Venus came out from behind the clouds, so I saw it for the first time up close! It was a bit fuzzy because of the clouds (which went away when it got dark), but it was both definitely not a star (too disk-like) and also not round (think a gibbous moon). Exciting indeed.

I was determined to get through my list, so that's what I went straight into. There was a little crowd of three doubles that I thought I'd tick off quickly, because they were close, but in the end I had trouble figuring which ones were which, which meant difficulty figuring out which direction to go in next. Didn't help that one was only 2 arcseconds of separation, so I probably say it and didn't realise. That was R227; I did however split Q Centaurus, and Rmk18. Go me. Happily, I also managed to find and split DUN128, chi Centaurus, and iota Lupus. And, accidentally, I found and split h4651 as well, and tau Lupus (1) also.

My big, smug-making achievement of the evening was finding the galaxy Centaurus A... admittedly, this was easier because it basically forms a straight line with Hadar and omega Centauri, and because it was so dark that it was naked-eye visible, but whatever! I still saw it through my scope!

Saturn, this time, had four moons basically trailing behind it like ducklings after their mother: Titan, Rhea, Tethys and Enceladus, according to Stellarium, getting closer. Plus the rings were incredibly crisp, as was the shadow on Saturn's disk from them.

I was on quite a high after finding most of the things on my list, so despite being freezing (according to J's scope it was 4C), I decided to grab the SkyMaps list and at least check off the naked-eye objects, in my continuing quest to learn my celestial cartography. Couldn't find five things, but only because they'd already set. But, for the record, I did find: Arcturus (in Bootes); Sirius (Canis Major); Procyon (Canis Minor); Canopus (Carina); the Coalsack (near Crux); Regulus (Leo); Antares (Scorpio); and Spica (Virgo). I was totally going to try for the binocular objects, but when I realised that the scope was dripping with dew and I would have to spend heaps of time swinging the scope around and around, I gave in and went inside.

J did show me some awesome things through his - I especially liked the Blue Planetary, a round nebula that really does look like a planetary disk.

All up, it was a brilliant weekend. Our star chairs - both Cats' Perches - were marvellous and very welcome for 2-hour observing stints. I have rarely been so thankful for my down-filled jacket, and the doubling-up of Explorer socks in my walking boots was awesome on Saturday. Plus, our headlamps - strapped to our heads, looking a bit dorky perhaps - with red cellophane inside? Brilliant! No longer worrying about ruining our night-vision with white light, and not having to use a bike light to read the map!

Mansfield nights

New moon weekend, and we managed to get away from Melbourne again, hurrah! The week had been cloudy and rainy in true Melbourne-autumn style, but we clung desperately to the forecast that the weekend would be sunny - and that Mansfield is on the other side of the Divide, so they get different weather. It looked incredibly unpromising as we drove away from Melbourne - no break in the clouds to be seen - but then, as we went over some hills, an amazing thing happened. The clouds were left behind, and the sky was a glorious blue. Joy!

I had me a list of double in Centaurus that I want to chase, so that's what I mostly did, over two nights.

Firstly, we saw Venus! on our way to dinner, but it's the first time in ages I've seen it after sunset - so bright!

Began by finding omega Centauri, the globular cluster, just for kicks and because it was naked-eye visible it was that dark. Also Mars, in order to get the Rigil in line; it's not nearly as interesting as it was a few months ago.

As for doubles, started off with Rigil Kent (alpha Centauri), which I managed to split although only just. When I then moved on to Hadar, the other Pointer, I realised that I had been somewhat optimistic: it's got a separation of just 0.9 arcseconds, which is really close. I reckon on really good nights I'll be able to split maybe 8 arcseconds? So no dice with Hadar, and I realised looking at my list that there were a good few of separations I simply wouldn't manage. Oh well; I found (what I think were) the stars anyway, for fun.

Also? I think I will have to learn the Greek alphabet since, according to J, referring to the stars' reference as 'the squiggly one with a bit on top'? Not so impressive.

The next attempt was on gamma Centaurus; also 0.9 arcseconds, also no luck. Alpha Circinus, however - score! 16 arcseconds. And yes, not in Centaurus, but just below so it totally counts. Gamma Circinus was another no-go, at 0.8 arcseconds, but I did find an unlisted double near it, so that's fine.

At about this point, the owners of the place where we were staying came out - I'd told them they should - so I found Saturn, and it looked awesome. In mine, I could see Titan a fair way out; a faint star close in on both sides, and another faint one on the opposite side. It turns out, through J's telescope, that those two close-in moons were actually both pairs! (Stellarium tells me they were Rhea/Enceladus, and Dione/Tethys, with Iapetus a long way out.) They were suitably impressed both with that, the telescopes, and the fact that we were outside at all - did I mention it was freezing? I was wearing multiple layers, although no beanie, which J thought was crazy but taking the glasses on and off with a beanie on is more trouble than it was worth.

I finished the night somewhat ambivalently. I found DUN159 and 133, but failed with I424 and R213 - imaginative names, aren't they? Then, having been outside for a bit more than 2 hours, we scurried inside to warm out near-frostbitten tootsies. Also, my scope was having a bit of a dew problem. J had rigged up a dew system for his, what with the mirror being bigger and all; he'd wondered whether mine would require it too. Having to wipe off the Rigil in order to see through it, and ditto the eyepieces? And discovering the front element had a fine mist of dew over the whole thing? yeh, that would be me requiring a gadget to act basically as a hot water blanket to my scope.

02 May 2010

Doubles hunter

With my brand-spanking new Double Star Atlas, I can now really and truly have a go at hunting doubles!

Last night was the first in ages that was actually clear. There were some high wispy clouds at sunset that had J panicking, but they went away so we went outside. As well as my Atlas, the other exciting new thing I have is a Cat's Perch! J's been talking about getting a star chair for months, and he ended up ordering two of these - it's so much easier to focus and hold steady when you're sitting down, rather than standing. He'd constructed them last weekend, and sanded them yesterday, so they were ready for a test. And I loved mine: I was observing to the west, so I ended up having the scope very low down and the seat correspondingly so. I could have had it higher, but I think that would have been more annoying.

So, what did we see? I started off with Saturn, of course; and it was lovely. I could definitely see the shadow band under the rings, and I could just see one moon, which was either Rhea or Dione. I then swung around and decided to play around in Canis Major, to see what doubles I could find and whether the Atlas is going to work for me.

Firstly, I'm glad it's spiral-bound. The Atlas has 30 double-page maps, with constellations and doubles and some other features marked. Then, at the back, it has the list that the authors worked from, of which doubles to include: this has the magnitudes and separations of the respective stars. This is very, very useful when you think you've found the right star, but you're not sure you can see a companion, so you need to know whether they're only 8 arc-seconds apart and therefore unlikely to resolve under light-polluted skies (which happened to me), or whether the companion is TWO HUNDRED AND SIXTY FIVE arc-seconds away and therefore could be one of three faint stars you can see (I am annotating the list as I go, with ticks and dates of when observed. This one I also annotated with "srsly?!"). The one problem - and this is only a problem for me, not the book - is that they're in right-ascension order. This has to do with how the stars are mapped, and I am struggling to really get my head around it. (Dumb moment of the night: realising that I was treating the lines of right ascension and declination as if they were straight, rather than curved....) This is something that I will get used to over time. I presume.

Anyway. Canis Major. Start with Sirius; no luck splitting. Move up to Wezen: success! (At least, I presume so; that's the 265" split.) No luck with Adhara (7" split, so not that surprising). Then, on to some harder ones. There's a little group of three along the 'spine' of Canis, two of which are noted as binaries. I hazarded a guess at where they should be, looked in the scope... and didn't think I'd found it. Asked J for some help, tearing him away from his open-cluster hunting, showed him the map... and he found exactly the same thing. I looked at it a bit longer - checked the list at the back - and realised that actually, one was a triplet, and that's what I'd been confused by: the top star in my eyepiece had two very faint stars nearby, which was indeed my triplet! This was also helpful because I now have an idea of what 44" looks like. That was 17CMA; sadly couldn't split pi, so that will have to wait for another night. After that success, I attempted tau-CMA, which is in the open cluster NGC 2362 - which, I didn't realise, is J's favourite little one. And I found it, and I think I saw the double; at 85" separation, in a cluster, it's hard to be positive.

Unfortunately, I didn't have a great end to the night. There's another little group of three, between Sirius and Mirzam, that looked like they should be easy enough to find - two are bright-ish, and they're convenient between those two very bright stars. I got quite frustrated because I just couldn't find them. So J had a go, and swapped in our widest eye-piece. Turns out I was looking in exactly the right place... but I had totally underestimated just how wide the set was. This is another thing I will have to get used to judging. Anyway: I split v-1CMA and v-3CMA (although the latter doesn't appear to be in the master list, which is odd).

The other thing I have to get used to, and adjust my expectations for, is how many things I will manage to see in a night. At the moment, the answer is not that many. J has much more practice with observing, and reading charts, and is not handicapped with a monumentally unspatial brain like me - so he's always going to see more. It's also a lot easier to tell when you've hit a cluster, than when you've hit a double, so he can skip around more easily if he wants to. I think this is something I can deal with... eventually... and as I keep reminding myself, the sky actually will stay basically the same for my entire life. It's not like I'm running out of time to do this.