B33. The Horsehead Nebula. This part of the night sky is my favorite. It lies about 1 degree south of the bright star Alnitak the most eastern star on Orion's belt at a distance of 1,500 light years. It is also very challenging to see visually. I can only truly say I have seen once on a very clear moonless night up in the Brecon Beacons national park using a ten inch reflector, a 40mm eyepiece and a Lumicon H Beta filter. However it is not that difficult to image, especially when using narrowband filters, evern in an urban site. The equipment I was using when I was imaging was my 4 inch f/6.3 refractor, a Vixen atlux mount. PHD auto guiding, an Atik 383L mono CCD camera and a set of Astronomik narrowband and RGB filters. I set the camera on X2 bin mode To increase the sensitivity of the camera and captured two minute sub frames. I then combined this data with matching dark frames and flat field frames to reduce the effect of noise and vignetting in the final image. The total exposure time was 1 hour using a blue filter, 1 hour using a H Beta filter, 2 hours and 50 minutes using an O111 filter, 3 hours and 50 minutes using an S11 filter and 13 hours and 7 minutes using a H Alpha filter.
RGB plus narrowband colour
