M52 and NGC 7635 - Bubble Nebulac

This area lies just on the border between the constellations Cassiopeia and Cepheus. M52 is a fine open cluster located in a rich Milky Way field. The distance of this cluster is not very well known, measurements indicate something between 3.000 and 5.000 light years.

Situated about 35 arcminutes southwest of M52 is the Bubble Nebula NGC 7635 around the 7th-mag star HD 220057. Within the diffuse emission nebula lies a dark inclusion which appears as a faint and diffuse oval, about 3.5 x 3 arcminutes in size, hence the name "Bubble Nebula". The bubble was probably formed when the nebulous material inside it was blown out by stellar wind of the bright OB star HD 220057. It is difficult to see because of its low surface brightness.

Exposure Data

Instrument: 8" f/5 Newtonian
F/stop: 4.75
Exposure: 17 x 10 min
Camera: ZWO ASI294MC Pro
Offset/Gain/Temp: 30 / 0 / -24°C
Date: September 11, 2018
Exposure start: 02:13 MESZ
Location: Wallackhaus, Carinthia
Conditions: Visual limiting magnitude 6.4 mag, SQM-L sky brightness 21.35 mag/arcsec², seeing 2.5" FWHM, temperature 2°C, no wind, slight dew
Autoguider: Lacerta MGEN
Enhancement: Basic data reduction, registration and combination, background flattening, color calibration, noise reduction, deconvolution, non-linearization, local contract enhancement, star size reduction
Notes: Thin high-altitude clouds passing through during the exposure series