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Contains:  M 52, NGC 7654, Bubble nebula, NGC 7635, NGC 7538
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NGC 7635 - Bubble Nebula & Vicinity, 


            Kurt Zeppetello
NGC 7635 - Bubble Nebula & Vicinity

NGC 7635 - Bubble Nebula & Vicinity

Technical card

Resolution: 3858x3078

Dates:Nov. 11, 2018Nov. 29, 2018

ZWO Ha 7nm 1.25": 41x180" (gain: 139.00) -10C bin 1x1
ZWO O-III 7nm 1.25": 50x180" (gain: 139.00) -10C bin 1x1

Integration: 4.5 hours

Darks: ~15

Flats: ~20

Bias: ~20

Avg. Moon age: 12.65 days

Avg. Moon phase: 35.29%

Bortle Dark-Sky Scale: 5.00 job: 2403171

RA center: 23h 20' 38"

DEC center: +61° 11' 2"

Pixel scale: 1.665 arcsec/pixel

Orientation: 194.631 degrees

Field radius: 1.142

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

Data source: Backyard


I have an image of the Bubble Nebula from three years ago when I imaged the globular cluster M52 for my Messier Catalog. Needles to to say, this HOO image blows it away. NGC 7635, the Bubble Nebula, is being pushed out by the stellar wind of massive star inside the nebula. Also in this region is a cloud of gas and dust in this region which is able to contain the expansion of the bubble gas. However, the gas gets heated by the hot radiation from the bubble's central star causing it to glow. The Bubble is about 10 light-years across. Also located in this image is M52 - Cassiopeia Salt and Pepper Cluster off to the right and the even more impressive NGC 7538 - Northern Lagoon Nebula to the left. I was going to crop the Bubble like many other imagers do but I saw the Northern Lagoon and decided to keep the large field. Besides there are many other great close ups of the Bubble with larger aperture scopes so I decided to keep the large field. The upper left portion of the image contains even more nebulosity and and not just hydrogen, the gas also had a strong oxygen signal as well.

I was not planning to image this object this year or at least with the ED80 as I thought my new telescope (ordered three months ago) would have arrived by now, oh well - I hear it is in California waiting to go through customs. I imaged this in Ha and OIII and did capture a little SII but chose not to add it as it was less than an hour and I was not happy with the focus. I am being more picky with focusing these days. In fact I through out a nights worth of oxygen as it was way out of focus. I thought my filters were par focal before learning the hard way that par focal is a bunch of hogwash. Unfortunately I did not have time to add any RGB for a star field either so this will have to do for now. I am looking forward to the new winter constellations most of which are visible from my astronomy shed which makes setup much easier.

Processing took a little while as always as I was trying new things in PI and PS. I took a short course on processing with PixInsight and Photoshop offered by fellow AB imager Shannon Calvert of the Westport Astronomical Society (WAS) the other night and picked up some new tricks especially with noise reduction. Of course it was on one of the few perfectly clear nights we have in Connecticut.



Kurt Zeppetello
License: None (All rights reserved)

Sky plot

Sky plot


NGC 7635 - Bubble Nebula & Vicinity, 


            Kurt Zeppetello