Saturday, 31 January 2009

Leo I

With this title I am not referring to the papacy, but the local dwarf galaxy near the star Regulus, which I was thrilled to pick up on this photo. Not a fantastically sharp picture, like some of those all-nighters on the internet, but artistically composed let's say. Those dedicated astrophotographers are blessed with fantastically dark non-misty skies and $1000s worth of equipment, whereas I have UK weather, UK light pollution, a hand made scope, a reconditioned D-SLR and little patience. There is also a 14th magnitude galaxy at the bottom - North is right on this pic. It was 6 x 30 second RAW images converted to TIFs, detrailed and then stacked in DSS (apologies for all the TLAs).

Thursday, 29 January 2009

A stellar tantrum

One of our Society (John G - please visit his blog: see link) bought a 2" UHC filter that he lent me, so being knowledgeable of the sky, and it being winter, I decided to try it out on a rather strange patch of nebulosity near Sirius called 'Thor's Helmet'. After screwing the filter in place on my Camera adaptor and refocusing, I did a range of exposures from 30 seconds to 3 minutes, all of the longer ones trailing, and some of the 30 second ones trailing also. I detrailed all the trailed ones using the filter manually in Paint Shop Pro 7 just as jpegs, and ran them through Deep Sky Stacker. I was struck with the beauty of the resulting picture that appeared in front of me. And when I processed them in PSP7 I was stunned with the result. DSS selected 18 exposures, most 30 seconds, 3 of about 70" and 2 about 3', but equivalent to ~30" because of the detrailing process, of which it took an adaptive weighted average. Thor's Helmet, NGC 2359, is 7º from Sirius and exists because of a frantic massive star, called a Wolf-Rayet star near its centre. There is Oxygen O III (or O2+) emission in the centre and Hydrogen clouds further out.


I did hours of detective work recently, trying to find which little smudge on my processed images corresponded to Saturn's outer moon Phoebe. Both my sky chart programs were completely wrong with its position and I had to follow-up with some more images 3 days later. It's a rather lovely name for a very porous, dim, reddish rock that orbits in a 550 day retrograde orbit. She spins in 9 hours, so is not tidally locked like the other moons (and our own), leading astronomers to think it could be a captured asteroid. I'm amazed it was detected in 1898; it's only 16.45 magnitude! Take a look at the hi-res Cassini pictures to see how unbelievably full of holes it is. It was a case of taking 4 x 15 second exposures for each area around Saturn and stacking them to reduce noise. Here is the labelled version of the Tuesday night (Weds morning) when more moons were visible. The planet is rather overexposed (if you were wondering where the rings are).

Sunday, 11 January 2009


I looked out of my window this morning and saw unexpected whiteness everywhere. There was no snow forecast, it was just a deep, powdery frost. So I went to my local heath to take some photos and as I climbed the hill I turned back and it was one of those rare occasions when you can look straight at the sun. It was wierd, like looking at a blank, white moon and I gave it a good stare, but I couldn't see any sunspots. I bracketed the exposures but chose the 1/2500" on ISO 100 with the Canon standard lens zoomed in to 70mm. This picture is a crop of a high quality jpeg and the optical quality is amazing, so I couldn't bear to scale the picture down (as I do for all the space pictures that overexpose stars into huge blobs). It was -4º with a breeze and I had no gloves, so in no time I had immobile hands and the autofocus frosted over.

My attempt at stitching photos together.

This is a worthy subject for a panorama: M33 the close spiral galaxy. It has lots of nebulae and clumps of stars visible - click on it and scrutinise the outer regions. I did 4 x 4 x 15 second pictures on the 20" scope with the centre of the galaxy in each corner and tried to stitch them together using the camera's software. The brightnesses were all different - I spent ages trying to adjust the brightness of different parts of the final picture but I had to stop sometime. I don't know of any free software that can easily correct for these subtle brightness differences. Anyway, my previous M33 pic (below) made it into print in my society's newsletter... but I've done as I said in the accompanying post and taken an improved picture (without any of those trailed smudges or the heavy blue bias).

Interacting galaxies

Blogger just lost my post because my finger accidentally fell on to the laptop touch-pad and clicked back on the browser! When I went forward again it was blank and so was the saved draft! Has anything similar happened to you? Anyway, enough ranting, here I present NGC 672 and IC 1727, and even a red galaxy PGC 1803573, which Andrew found out for me - the guy who does the 'littlebeck' blog. Can you see that the galaxy on the right, IC 1727 is a distorted former barred-spiral?

Friday, 9 January 2009

Cosmic Keyhole

This nebula is pretty easy to find - it is just below the Orion Nebula. NGC 1999, or the Keyhole nebula, for obvious reasons. It is quite striking in appearance due to the cloud of cold, dark 'dust' blocking the lit clouds behind. It is a reflection nebula, so I tried to process it to bring out all the faint outer nebulosity. Visually, it didn't look like much: just a smudge around a faint star, even in the 20" scope.

NGC 1535

I made the most out of the clear sky on Boxing Day, so here is another planetary nebula, in the constellation of Eridanus, NGC 1535. It looks a bit like a small version of the eskimo nebula and no doubt some budding astronomer has tried to name it, but I know it as NGC 1535 now, even though it's just a bunch of letters and numbers. It's got a second star in it, although I'm not sure whether this is a line-of-sight effect or not; surely in a close pair of stars one star can run out of fuel first and release it's atmosphere into space.

Tiny planetary nebula

This picture is of a tiny planetary nebula in the constellation of Lepus, called IC418. From the Hubble picture, it was christened the Spirograph nebula. This picture might not be particularly good but when I looked at it with a high magnification, it looked like a star surrounded by tiny pink rose petals. For some reason the central star is trailed, but the exposure was only 1 second taken remotely at the ISO800 setting on the camera. Unless there was camera shake, I have to presume the central portion of the nebula is elongated. I had to double the width and height of each pixel for this image. There appears to be a bit of structure in the pink disk.