It moves!

Nov. 9th, 2007 12:15 am
fivemack: (Default)
A squall-line came over this afternoon, down from the Orkneys on the wings of a tree-felling and ship-sinking wind, bringing behind it beautifully clear sky; Ed had said that he'd tried and failed to photograph the comet, so I wondered if it had faded substantially, and went out with a range of cameras.

With my little camera (Canon Powershot A510; 15s f/5.5, 140mm-equivalent, ISO 400) I get the left-hand picture. It's not a good picture - the lens is flaring badly around the brighter stars, and the colours are much too blue, with alpha Persei looking the actinic-blue of an O-type star when its spectral type is a more prosaic F5 - but it's a 200-gram pocket camera not intended for astronomy; the right-hand picture is with totally different kit but at about the same scale, taken by me on Saturday, to show that the comet is moving.

With a camera of inconvenient size (Nikon D100; 200mm, f/2.8, the camera and lens weighing in at 2.3kg, 4-second exposure at ISO 1000, push ISO up a couple of stops in gimp cursing at the lack of 16-bit-per-channel support) I get

So it's still pretty visible to me; I'm surprised that Ed couldn't get a picture of it without sky-fog issues (in that it's a lot brighter than sky-fog to me, and would be visible through it unless the exposure was so long that the sky-fog saturated), unless where he lives is a lot more floodlit than a central-Cambridge back garden.


Nov. 4th, 2007 12:36 am
fivemack: (Default)
As I came back from the Parkside ceilidh this evening, I noticed that the sky was clear, Comet Holmes visible to the naked eye as the corner of a triangle in Perseus which I knew wasn't there the last time I admired Perseus (the comet grew brighter by a factor 30,000 about ten days ago), and my brain not entirely befuddled. So I set up the most elaborate camera gear I had access to on a tripod in the garden, and got this:

I'm sure I can do better - I didn't set up the impressive telescope that [ profile] major_clanger lent me, because there was only one of me and it was midnight, and I've really done very little processing on the raw camera output. In particular, there are bright green stars in the photo above, and those don't exist. That picture is a few-second exposure at 80mm f/2.8 ISO1000 with my Absurd Photojournalist Lens; exposures at 200mm f/2.8 make it look bigger but not obviously better:

The geometry of this comet is a bit odd - basically we're between it and the Sun, so the tail is pointing directly away from us and visible only as the elongation of the coma.
fivemack: (Default)
I have a telescope, and the weather is now such that I from time to time wish to use it. OK, it gets dark somewhat unreasonably late at the moment, so the list may get more active come the autumn; Mercury's in quite a good position this week at around sunset (say 8:30), Mars is in conjunction with Saturn on the 17th - both planets will appear in a single telescope field of view - so I'll start off by inviting interested people to my place, and thence to the top of Castle Mound, that evening at eight-ish.

[though it's Suicide Sunday the next day, so possibly everybody will be at May Balls, or Pimms- and Camwater-sodden after the CTS punting]

If any Cambridge people would like to be added to a list of people to be invited to admire the stars when my fickle fancy takes me, please comment here:
fivemack: (Default)

Some pretty pictures, and really rather good didactic commentary.

Also, to do for geography what Jane Austin and the Flying Moose of Nargothrond do for literary criticism, consider the following map
fivemack: (Default)
NASA has cancelled Dawn, an ion-drive-propelled probe intended to visit two large asteroids.

A large portion of the spacecraft, including the two cameras provided by European organisations, has already been built - it was intended to launch in June. The budget was about 300 million Euros, much of which (though presumably not the launch vehicle) has already been spent. It would fit easily on an Ariane 5 - indeed, it's too small for it to make sense to launch it on such a vehicle; I can't quite tell whether it would fit on a Soyuz.

There's no competing ESA mission; so the question is, could NASA be convinced to let the mission be taken over by ESA, and could ESA be convinced to pay for it?

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