Wednesday 7 September 2011

2011-09-06: More Supernova Images

Last Monday, around 23:00 UTC, I tried to take a picture of the supernova in M101 from a dark place in Salamanca (Boada) using my C8 with its default mechanical fork mount. It was aligned manually using the AR and DEC scales together with an illuminated micrometric reticle eyepiece. Without any computerized aid (i.e. no GOTO function)! As imager I mounted a standard Canon EOS DSLR in the prime focus together with a focal reducer to convert the usual F10 of the scope into an effective F3.3. The purpose was to configure a very fast imaging ensemble. However, this configuration has the inconvenient of a significant image distortion out of the optical axis. The used focal reducer design is not able to flat the prime focus over the large size of the Canon CMOS sensor. Despite of this problem, the alignment and imaging configuration allowed non guided exposures of 3 minutes. Finally, the Moon limited the effective exposures to 90 secs.

As a first test for the alignment, I tried to image M51. The image below shows the result. It has been composed stacking 4 exposures of 60 secs. Later I found that M51 houses a recently discovered SN. It is marked by a red arrow in the image. For SN identification, this image can be compared with another image of M51 that I posted here on 2007/06/22.

Then, I pointed to the main target of the night and I take several exposures. The following image shows M101 and its SN signed by a red arrow.. It is the result of the stacking of 6 exposures of 60 secs and 4 exposures of 90 secs.

My final impression of this experience it that the results are not bad, specially if it is considered that they are produced with a manual alignment.