This is the bright 7-Sisters star cluster in Taurus visible high in the winter northern skies. This is a target that has been long on my list of failures – results have previously been poor with not having the right focal length and not taking enough sub-frames. It’s a broadband object so it is also at the mercy of light pollution.
Whilst the stars are bright the reflection nebula surrounding this cluster is quite faint and easily swamped. Bringing out the reflection nebula without saturating the stars requires choosing an exposure length that does not clip the stars and then take lots of exposures.
I decided that it was a good target for my un-modded, uncooled Canon 550D, matched to my 70mm APO refractor to give me a good level of detail with some surround star field for context. The result above took 479 x30sec exposures (4hrs). It was processed in Pixinsight and finished off in Paintshop Pro as a full frame resized to 30%. If I took another 4 or 8 hrs(!) I might be happy to display this at native resolution.
The HEQ5-Pro continues to be an excellent mount for this scope. Basically, its sub-arcsecond tracking accuracy with this load means it’s rare to lose a frame due to mount errors.