Friday, 20 February 2009

A couple of nice spiral galaxies

If you can recognise these, you have passed the test as a good experienced amateur astronomer. As a further clue, I also got a decent picture of a galaxy nearby, just one field width off to the North. I believe 6 x 30 second pictures on the 20" telescope is all it took to get the raw pictures, but the processing was what removed the light pollution and brought all the detail out, especially on the left galaxy.

The Night-Knight

Yes it's a rubbish pun but this looks exactly like the chesspiece. I took a plethora of exposures of assorted lengths through John G.'s filter and detrailed them all eventually. I have found an alternative way of doing this in Paint Shop Pro 7 using layers and 'darken' like the Photoshop method. The result looks quite good small. Pretty smooth. I played around with the pixel value mapping curves to process the stacked image. The vast red cloud IC 434 shines in hydrogen light so it's called an H II ('H-two') region. This light, unfortunately for our visual range of colour, is mostly 656.28 nanometres (H α) in the red, but a very tiny proportion is H β at 486.13 nm, which is in the blue region, enabling us to see it, barely! It's still too faint for my liking - the best I saw was a smudgy line with a gap in it where the horse's head is. This gap is a dark nebula, a dense protrusion called Barnard 33 (B 33) or The Horsehead Nebula that is part of an awesomely sized dust cloud floating in front of one side of IC 434. The blue cloud is a reflection nebula (NGC 2023).