Orion Nebula

Winter is usually a great time for astronomy with longer nights and the sun setting at a reasonable hour, with the forecast for last Friday as clear until 12am I thought I'd put in a few more hours imaging. I hadn't realised it was a waxing gibbous moon until after I'd lugging all the gear outside and started setting up.

A nearly full moon, combined with a slightly hazy sky limited the choice of objects severely. The moon was out of the question, as I've yet to buy a moon filter, even on the lowest exposure setting of 0.001 seconds the ccd chip was becoming fully saturated. So I turned instead to the Orion Nebula, M42.

At magnitude 4.0 the nebula is visible as a fuzzy gray blob to the naked eye, just below the belt of Orion. I took a total of 90 exposures (81 usable) at 15 seconds each in an attempt to not burn out the central core on the 15 second exposures, whilst bringing out the fainter detail.

• Exposure Time: 15x81s Avg
• Date: 2007-11-23 23:47:55 UTC
• CCD: Starlight XPress MX716
• Scope: LX90 8"
• Dark Frames: 15x15s Median
• Apparent Dimension: 85x60 arc min
• Visual Brightness: 4.0 mag

Since it looked neat, I've uploaded a pseudo colour version, this isn't in anyway the true colour of the Orion Nebula, I don't have any colour filters yet :)

I believe this is my best image to date. Although it's still not quite in focus, the exposure was perhaps too long resulting in a burnt out core. Not to mention the moon/haze made post processing a nightmare with a bright central light gradient to remove.

Collimation of the scope is still slightly out. I spent an hour before taking this image to improve it a little, but it's going to take stabler skies before I can collimate at a reasonable magnification. I think the sky stability and lack of good collimation is partly to blame for the difficulty in achieving a good focus.

I'm looking forward to re-imaging this object on a moonless night to see how big an improvement I can achieve.