NGC 404 - Mirach's Ghost

I was not planning to image Mirach and the Ghost (NGC 404) as I just needed a bright star to carefully check how far off or how close each filter's focus is from one another.  I assumed they were all par focal since they were same brand but I had my doubts.  I recently shot the Bubble in Ha and then the following night in OIII. On the second night I checked the focus in luminosity.  The night was wasted, after stacking, it was clear the focus was way off. After some research and AB communication with Gary Imm I discovered there is no real such thing as par focal.  I don't have a fancy electronic focuser that takes care of offsets so I thought I would see if I could make a chart and do it manually.  That really did not work however I did get much better at focusing and discovered that the LRGB and Ha are very close, beyond detection, however, the OIII and SII were different.  From now on I will carefully check each filter in particular the narrowband filters.  I re-imaged the Bubble in OIII last night and although I did not stack them, the individual subframes were far sharper than I have seen in my previous OIII images.

The Ghost is a dwarf lenticular galaxy, similar to the Small Magellanic Cloud.  Astronomers suspect one or several mergers with smaller galaxies roughly 1 billion years ago caused star formation and that NGC 404 is a former spiral galaxy that was transformed into a lenticular one by those events.

In my image NGC is to the lower left within Mirach's shine.  I did not crop it much as I liked the star field and this was more of a test anyway.  Several blue and yellow stars are scattered throughout the image.  Mirach or Beta Andromedae is a red giant 197 light-years from Earth and has an apparent magnitude of 2.05 - perfect for focusing practice.

NHC 404 - Ghost of Mirach
Location: Home Monroe, CT
Date: 11-27-18
Camera: ZWO ASI1600MM-Pro
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
f/7.5
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Atlas Pro
Filter Wheel: ZWO EFW 8x 1.25"
Filter: ZWO R, G, B
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: R 10 x 90, G 13 x 90, 16 x 90 (58.5 min total)
Gain: 139
Offset 21
Temp: -10 C
Post Processing: PixInsight and Photoshop
https://kurtzeppetello.smugmug.com/