Andrew’s Astronomy Blog

Tuesday night was pretty clear so after taking the pictures of Albireo on the club’s 20″ reflector I switched to M27. The 20″ has some problems with tracking and field rotation as it’s on a motorised Dobsonian mount so it’s best to use a high ISO setting on the camera and keep the exposures as short as possible. I took 30x 20 second exposures at ISO 1600 and 15 were usable although there’s some elongation visible in the final image.

M27 is a planetary nebula, recorded by Messier in July 1764. It lies about 1000 light years away in the constellation Vulpecula.

 Ask any person in the street what colour stars are and you will usually get the answer; White. However, a closer study with the naked eye will reveal some differences in colour and with binoculars or a small telescope this is more apparent. Some double stars show a marked colour difference between the pair and this is apparent in this example, Albireo, the star marking the head of the swan in the constellation Cygnus.

Once you get past the members of the Local Group, the next nearest galaxies are in the Sculptor cluster. Back in November last year I posted an image of  NGC 253 and this time it’s the turn of NGC 247 in the constellation of Cetus.

 At a distance of about 12 million light years this is a rather distorted spiral galaxy, with a prominent star at one end and a sparce void at the other. Being relatively close, the galaxies in this group appear quite large, this one is about 2/3 of the diameter of the full moon in length but is too faint to be visible to the naked eye. The small galaxy in the lower right of the image is PGC002795 (ESO540-026).

This is a picture taken with GRAS-006 in Australia and consists of 3 five minute exposures. GRAS-006 is an RCOS 16″ - FL 3654mm @ f/9.0 with an SBIG STL-1001E NABG camera.

With Jupiter so prominent in the evening sky it’s hard to take pictures of anything else. Saturday night was clear and I stayed out to image the moon Io crossing in front of the planet. Unfortunately, a fundamental error meant I inadvertently left the f/6.3 field flattener on the telescope and didn’t notice until I’d packed up at 12:30 and this has spoiled what otherwise may have been reasonable images.

Best of the lot is this one, an RGB composite of about 700 frames of each colour .