The Seven Sisters (Pleiades) Star Cluster

Early Thanksgiving day morning I imaged a favorite star cluster of mine, the Pleiades or Seven Sisters. The Pleiades, also known as Messier 45), are an open star cluster containing middle-aged, hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky.  The cluster is dominated by hot blue and extremely luminous stars that have formed within the last 100 million years. Dust that forms a faint reflection nebulosity around the brightest stars was thought at first to be left over from the formation of the cluster (hence the alternative name Maia Nebula after the star Maia), but is now known to be an unrelated dust cloud in the interstellar medium, through which the stars are currently passing. (Wikipedia)

M45 (The Pleiades) - Nov 23, 2017
WO-GT102 and QHY10 Camera
30x300sec Subs at -20C  - f5.5

This image is a processed stack of 30, 5 minute subs, taken with my WOGT102mm APO refractor and QHY10 camera.

New Images

I just noticed that a good portion of my past images have not had the correct dark frames processed on them. This means that thermal noise from my camera was not getting subtracted out. Granted the QHY10 operating at -20C doesn't produce a lot of thermal noise, there is still some there and it should be removed.

Adjusting for the new parameters in PixInsight I re-ran the M33 image taken with my WO GT102 APO. The image is a little darker, but the noise is greatly reduced. I may decide to reprocess some of my past images to allow for this improvement.

Updated M33 with Dark Frame Subtraction

On November 24, 2017, I placed my main telescope on automatic and scripted it to take ~3.5 hours of NGC 891, an edge on spiral galaxy while I got some needed sleep :).  Results were really good. 44 subs, each 300 seconds long were taken in the wee hours of the morning. Here is the end result of that session.

NGC 891, Nov 24, 2017
EdgeHD11 at f7.0 - 44x300sec subs with QHY10

NGC 891 (also known as Caldwell 23) is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. It was discovered by William Herschel on October 6, 1784. The galaxy is a member of the NGC 1023 group of galaxies in the Local Supercluster. It has an H II nucleus.

Back in business

A few nights ago my main telescope mount started to act erratically. It would swing uncontrollably in the RA axis and resetting power didn't help.  Thinking the worst - a bad motor control board or motor, I removed the RA motor and tested it out.  Sure enough, when the RA motor was connected to the DEC axis the problem occurred. The issue is definitely correlated to the motor.

I contacted Ed at DeepSpaceProducts for the availability of a new motor. after describing the issue to him he suggested I first open the motor's encoder casing and check to see if the encoder assembly is OK since it sounded like an encoder problem to him. I found that the encoder disk was loose. Once tightened the issue was resolved. That saved me about $180. And, as usual, Ed is more interested in getting his customers back in business than he is just selling product.

Testing on real imaging last night reveals that the RA motor is fixed.

Not to waste a clear night, I set up the William Optics 102mm APO to capture some galaxies. Here is M33, the Triangulum Galaxy, also known as the Pinwheel Galaxy.

The Triangulum Galaxy is a spiral galaxy approximately 3 million light-years (ly) from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC 598. The Triangulum Galaxy is the third-largest member of the Local Group of galaxies, behind the Milky Way and the Andromeda Galaxy. It is one of the most distant permanent objects that can be viewed with the naked eye.

M33 - Nov 22, 2017
WO GT102 - F/5.5 29x300sec QHY10 Camera