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Contains:  NGC 404, The star Mirach (βAnd)
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NGC 404 - Mirach's Ghost, 





    
        

            Kurt Zeppetello
NGC 404 - Mirach's Ghost

NGC 404 - Mirach's Ghost

Technical card

Resolution: 4088x2920

Dates:Nov. 27, 2018

Frames:
ZWO B 1.25" optimized for ASI1600: 16x90" (gain: 138.00) -10C bin 1x1
ZWO G 1.25" optimized for ASI1600: 13x90" (gain: 139.00) -10C bin 1x1
ZWO R 1.25" optimized for ASI1600: 10x90" (gain: 139.00) -10C bin 1x1

Integration: 1.0 hours

Darks: ~15

Flats: ~20

Bias: ~20

Avg. Moon age: 19.42 days

Avg. Moon phase: 77.41%

Bortle Dark-Sky Scale: 5.00

Temperature: -2.00

Astrometry.net job: 2392592

RA center: 1h 9' 43"

DEC center: +35° 37' 30"

Pixel scale: 1.665 arcsec/pixel

Orientation: 196.632 degrees

Field radius: 1.162

Locations: Happy Frog Observatory, Monroe, Connecticut, United States

Data source: Backyard

Description

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.

Comments

Author

kurtzepp
Kurt Zeppetello
License: None (All rights reserved)
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NGC 404 - Mirach's Ghost, 





    
        

            Kurt Zeppetello