M40 Double Star in Ursa Major

Sometimes I find there are nothing like as many stars to see as other times.

 

Take this picture which includes M40, a pair of bright stars that Charles Messier thought was a double star. It is in Ursa Major (or the Plough, near to Megrez the star that connects the handle to the plough).

 

The stars form an optical pair, lying along the same line of sight, but not physically connected to each other as they are now known to be at different distances from Earth. One is about 470 light years away and the other is over 1000.

 

Messier was trying to identify nebulae but at that time it was hard to distinguish between galaxies and nebulae. This one of the few objects that made it into his catalogue that were neither.

 

What he missed were two spiral galaxies that my C11 picked up near to M40. The larger one just under the word Major is NGC 4290 and the much fainter one below that is PGC 39934.

 

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Telescope: Celestron C11-A XLT Schmidt Cassegrain OTA

Mount: SkyWatcher EQ6-R Pro

 

Controller: ZWO ASIAIR Plus 256G

Main Camera: ZWO ASI533MC Pro at -10C

Filter: ZWO UV/IR cut filter

Focuser: ZWO EAF

Guide Camera: ZWO ASI174MM Mini guidecam

Guide via: ZWO OAG

 

Stacked from:

Lights 12 at 120 seconds, gain 101, temp -10C

Darks 30 at 120 seconds, gain 101, temp -10C

Flat 30 at 430ms, gain 101, temp -10C

Dark Flat 30 at 430ms gain 101 temp -10C

 

Bortle 4 sky.

Integrated the saved frames in Astro Pixel Processor.

Processed in PixInsight

Added captions in Photoshop CS4

 

 

 

Done