Thursday, 30 October 2008

Cosmic Catherine Wheel

I went galaxy hunting the other night. This is a closer up version of the pinwheel galaxy or M33, shown below when I tested my 400mm camera lens. I got 6 30 second pictures on the 20" scope, all were very trailed in different ways, but I detrailed them all seperately, painstakingly! Then I stacked them, hoping that the trail artefacts left over would somehow "average out". Anyway there was a lot of red background noise, so I had to make the colour a bit bluish for the galaxy to stand out - as its light is very spread out. Good result I think?

A distant galaxy cluster

This is the faintest thing I've tried to take a pic of so far. It's 4 exposures combined from 15 seconds to 1 minute on the f/4.8 20" scope, at ISO 1600 (fastest film setting) on my Canon Camera. It looked good considering it's a collection of 14th magnitude galaxies. It is in Pegasus, near NGC 7331 and is called Stefan's Quintet. I've even picked up one galaxy on the image that's not in the PGC/UG catalogue on the far lower left! Impressive for such a short exposure, but not good for traces of trails left from my de-trailing

Monday, 13 October 2008

An autumn gem

NGC 246: I have always had trouble seeing this object as its light is spread over a large area, but I got a good view at low power through a nebular filter. It lies right in the middle of a triangle of stars including Diphda in western Cetus and its central star is double (3.8"). It is a close planetary nebula, well, close in planetary nebula terms at 2100 light years (Hipparcos). Sometimes called the Skull nebula, it is in Patrick Moore's Caldwell Catalogue at number 56 and was discovered by William Herschel in 1785.

Shakespeare's characters reveal themselves

Logically, following the image of Neptune's big moon, Triton I wanted to see other faint moons. Conversely, the moons around the much closer and 7 times brighter planet Uranus are fainter. However the brighter ones number 4 or 5 and rather poetically they are all named after characters from Shakespeare plays. In this picture, comprising of thirteen 3.2 second exposures, I just managed to get three. Fifteenth magnitude Umbriel is hiding just south of the planet's glare; below it are Oberon and Titania at 14.2 and 14.0 magnitude respectively. Also, rather confusingly is a faint star. This is a preliminary picture, which I hope to improve on as it is somewhat trailed and inexactly focused.

Sunday, 12 October 2008

How far south can you comfortably go?

I wanted to get a nice pic of NGC253 - the Sculptor galaxy and surprise folk by the fact it was in Sculptor, a constellation that is barely visible from UK. But to my astonishment, one of our club's members had just got a beautiful shot of it taken via the web on a Ritchey-Chrétien 10" in Australia. Nevertheless, I got a shot of it the following night on the 20". It's had a lot of light pollution subtracted off and I can't say my flat field was good enough to correct for the vignetting effect at the edges.

20" Mirror Test - part 2 small targets

One of my challenges since seeing Triton around Neptune in a 10" scope, was to image it. I didn't realise how easy this would be. It only took a few 4 - 10 second exposures on the 20" scope to easily capture Triton, which is 13.5 magnitude, and pinkish compared to Neptune's bluish. The separation is about 15 arc seconds, so there is either a tiny bit of coma or more likely inexact focusing.

20" Mirror Test - part 1 deep sky

The mirrors on my club's 20" have just been resilvered, and recollimated. I had to test it out, but my camera's adapter was too long, so I improvised and just tied and strapped my camera on. This is NGC 6781, an 11.8 magnitude planetary nebula in Aquila the Eagle. It looked great... pretty bright for something that magnitude and all of 1.8 arc minutes across. This was 11 x 30 second exposures.