2012 08 16 – NGC7635/H 4.52/Sharpless 162/Caldwell 11/Bubble Nebula
NGC7635/Sharpless 162/Caldwell 11/Bubble Nebula/H 4.52
Emission nebula in the constellation Cassiopeia, 23h 20.7m, +61 deg 12´, 15´x8´
Distance: ~11 kly, apparent magnitude: ~10
Discovered in 1787 by William Herschel, this emission nebula lies SW of open cluster M52 and west of open cluster Czernik 43. It lies at heart of 8th magnitude star TYC4279-1582-1 where two imaginary lines form a cross-shaped star pattern with 7th magnitude HIP115198 at the top (southwest), TYC4279-930-1 (northeast), TYC4279-381-1 (southeast), and TYC4279-1203-1 (northwest).
75x magnification: At first glance, the 7th magnitude star to the SW drowned out any nebulosity of NGC7635. My only certainty that I was in the right area was by knowing the star pattern and where NGC7635 was located within it. The use of an OIII filter brought out a faint, clear circular glow around the 8th magnitude star.
225x magnification: Without the OIII, there was a faint circular glow with no definitive structure. With the OIII and adverted vision, the nebula was elongated north to south and extended more to the NW with some darkened areas within it. The edges were diffuse.
Sketches created with AL template, #2 graphite pencil, loaded blending stump with charcoal, super-fine Faber-Castell Pitt artist pen “S”, 0.5mm mechanical pencil.
For a good comparison, my husband, Paul, took this image using an hydrogen alpha filter in 2007. The magnification would be similar to the 225x sketch. You’ll need to rotate it ~10 degrees clockwise to match the orientation.