Thursday, 31 December 2009

in the wee hours

I got an early look at the dark, spring sky the other night. I went down to the observatory at 2am. This was the only non-moonlit clear free period I have had where it has been safe to travel, i.e. above 0ºC, just. I got the scope ready well before the moon set at 3am. It is a better time to observe, because a few people will actually turn their lights off and headlights become very scarce. Although there were a few flashes of lightning and a little mistiness to the upper atmosphere it was pretty still air and Mars looked surprisingly detailed, with 2 surface features visible and a lighter polar region. When I looked it up, the diameter was only 12"! However, as per usual, the scope did not track well enough for photography. I was getting nice 1/800" ISO 100 pics of Mars, but when it came to long exposures the wobble looked terrible. I had a quiet* battle with the tracking for a couple of hours until during an ascending slew, the declination motor decided to scream and stall on me (* the motors actually make a loud, quirky, metallic noise while tracking). After a gentle push, I found that a bit of weight on the scope helped.

By this time, the constellations Crater and Corvus (the cup and the crow) were up in the south. Scanning my cerebral databases I headed towards the Antennae galaxies. So here is my picture. Taken around 5 am, about 24 reasonably tracked pics of the Antennae galaxies (NGC 4038 and NGC 4039), at 30" exposure, ISO 1600, f/3(ish), stacked, processed and tweaked. It's a fascinating object and the word 'object' is a bit of an understatement. The faint 'antennae' are stars flung out by the combined gravitational interaction of the merging galaxies' stars. In the centre of the galaxies there are bright patches that are zones of star birth triggered by gravitational shockwaves in the material, brought about by the galactic collision. To reveal the antennae was well worth putting up with the freezing wind blowing on my face for 5 hours.

Wednesday, 23 December 2009

Frosty cloud

I haven't been able to get to my observatory despite some lovely clear skies! Ice and Snow, minus 4, minus 5... Oh well, even if I did make it the light pollution is 10 times worse because the snow reflects street lights up into the sky. Plus I'm saving petrol (carbon). I created this misty effect by building a mask using the luminance value, inverting it and applying a 5 pixel gaussian blur. Any guesses as to what this mystery object is? (Hint: there's an easy way to cheat).

Friday, 18 December 2009

The Geminid Meteor Shower

I caught a Geminid on film during the mostly cloudy night of Sunday the 13th of December. It's a game of luck to get meteors on film. During my imaging stint, which comprised of exposing a camera on a tripod, I saw several Geminid meteors. But only on the way back home at about 00:30 I saw a beautiful green firework shooting slowly down to the east. Through thin cloud, this thing was amazingly bright, it must have been about mag -4. The one I got in this photo I didn't see - it is the only one I got out in about 30 photos! It'a a bit rubbish, but there was plenty of activity and I thought I would 'report' it on this blog.

Wednesday, 9 December 2009

Eris 2

Here's the second pic of the animation as it doesn't work.

New record for the Society's 20" telescope

Being able to image the solar system's faint outer moons Triton, Hyperion, Phoebe has whet my appetite for obscure astronomical targets. I set to work looking for the solar system's outermost visible object, Eris (I still liked the name 'Xena' better). Eris is 96.7 astronomical units away. This is a crazy distance! Three times that of Pluto. It's therefore receiving 1/9th the light, and only 1/9th of THAT light will get back to Earth. This object really pushed the limits of my imaging system. This comprises of stepper motors, worm gears, an MS-DOS program, an Alt-az hand built Newtonian telescope, a field flattener and a Canon EOS 350D (at about 8ºC). The site is now fairly light-polluted but we have a dome. Eris was about 30 degrees up in the South when these images were taken (13 days apart). It has only moved a few arc minutes (mostly parallax shift) in this time because it is so far away and that is how it evaded detection before Jan 2005. It has a moon, Dysnomia, discovered Oct 2005. Using the moon to 'weigh' Eris, it is now known to be more massive and also larger than Pluto, thanks to Hubble's impressive measurement of its size. I really had to optimise the stacking and processing of each of these images. The second image (Eris on right) is noisier, despite more (43 (cf. 32)) 30 second images. These are cropped and put together into an animated gif.

See "littlebeck" blog on my links - for the necessary images that reassured me that my blobs were Eris.