Andromeda Galaxy (M31)

The Andromeda Galaxy (also known as Messier 31, M31, or NGC 224) is the nearest major galaxy to the Milky Way (about 2.5 million light years away) and getting closer all the time. It is hurtling towards us at about 250,000 miles per hour and will collide with the Milky Way in around four billion years. Our solar system will probably be tossed much farther from the galactic core than it is today. M31 is a spiral galaxy spanning approximately 220,000 light-years and containing about a trillion stars.

 

I look forward to imaging this object every year because each time more details are captured. This shot was really just an experiment to try out three things: capturing the object using the ZWO ASI1600MC Pro camera instead of a DSLR; testing the polar alignment tool in SharpCature Pro to see if it makes an improvement; and finding a good method to make a mosaic in order to get more of the object in the frame. All three experiments were successful. I knew the ZWO ASI1600MC Pro would create a better image but because of its slightly smaller sensor size the field of view is also a little smaller so there is more of a need to make a mosaic to capture a huge object like M31. This image is just a two panel mosaic in order to include the two visible companion galaxies and there is a lot of overlap but future shots will hopefully be four panel mosaics so the entire galaxy is within the frame. Up until now I haven't had much success matching the backgrounds with mosaic shots but using Microsoft ICE really made a difference. I was very pleased with the polar alignment tool in SharpCature Pro. Recently polar alignments have been a bit hit and miss, sometimes very good but often terrible meaning poor guiding, streaky stars on some subs or having to use shorter exposures. The problem was becoming more frustrating with precious time wasted on poor subs that then have to be discarded. The solution was to either fork out over £200 on a system like PoleMaster or spend a tenner buying the licence for SharpCap and having access to its polar alignment tool. It was a bit fiddly first try but we got from our usual polar alignement, which the software designated as "fair" (about 3-5 arcminutes off), to "excellent" (about 17 arcseconds off). Wow, what a difference! We didn't have to throw out a single frame and if the sky was dark enough we'd be able to take 25 minute exposures now. Unfortunately with London skies being what they are we are still limited to around 5 or 6 minutes. Despite weather forecasts predicting a clear night, conditions were in fact pretty awful with thin high cloud and terrible seeing so it's kind of miraculous that this much of the galaxy was resolved. When we get a properly clear night with no Moon it will be worth making another attempt.

 

Information courtesy of Wikipedia and NASA:

en.wikipedia.org/wiki/Andromeda_Galaxy

science.nasa.gov/science-news/science-at-nasa/2012/31may_...

 

Two Panel Mosaic

Panel 1

014 x 300 second exposures at Unity Gain (139) cooled to -20°C

030 x dark frames

040 x flat frames

100 x bias/offset frames

Binning 1x1

 

Panel 2

019 x 300 second exposures at Unity Gain (139) cooled to -20°C

030 x dark frames

040 x flat frames

100 x bias/offset frames

Binning 1x1

Total integration time = 2 hours and 45 minutes

 

Captured with APT

Guided with PHD2

Polar Alignment with SharpCap Pro

Processed in Nebulosity, Fitsworks, Microsoft ICE and Photoshop

 

Equipment

Telescope: Sky-Watcher Explorer-150PDS

Mount: Skywatcher EQ5

Guide Scope: Orion 50mm Mini

Guiding Camera: ZWO ASI120MC

Imaging Camera: ZWO ASI1600MC Pro

Baader Mark-III MPCC Coma Corrector

Light pollution filter

Done