ASTRO:
     type=Emission nebula
     mag=(unk)
     const=Casseopeia
     dist=8000 ly; size=140 ly
IMAGE:
     location=Marathon Motel & Sky Park _ Marathon, TX
     BrtlCls=1
     moon=0% (new)
     exposure=CMOS OSC 40x300s (3.3 h),  G100
EQUIPMENT:
​     optics=ES102CF APO / Starizona "L" 0.65x rdcr, FL(eff.)=464mm, f(eff.)/4.55
     camera=ZWO ASI2600MC-Pro
     filter=Optolong L-eXtreme DuoNB
     mount=Celestron AVX
     guiding=Orion 60x240mm, ZWO ASi224MC
SOFTWARE:
     acquisition=Stellarium, NINA, PHD2,
     processing=PixInsight (RCAstro), Photoshop (WebSharpPro), LrC

Sharpless 157 (or Sh2-157), sometimes referred as the "Lobster Claw" nebula, is an emission nebula in the constellation Cassiopeia.  It is located appx 8,000 light years away from Earth.  The predominantly red part of the nebula is a very large H-II region that is ring-shaped by the stellar winds of several giant stars, including the bright and very young Wolf-Rayet star, WR 57.  The blue-ish colored regions at the right part of the nebula mainly consist of highly ionized oxygen (O-III) and other gases. The small open star cluster NGC 7510 is located toward the lower right.

NGC 7635, also known as the Bubble Nebula, and as Sharpless 162 (or Sh2-162), and Caldwell 11 (or C11), is an H-II region emission nebula also in the constellation Cassiopeia.  It lies close to the direction of the open cluster Messier 52 located in the upper right corner of the image's field-of-view.  The "bubble" is created by the stellar wind from a massive and hot, magnitude 8.7 young central star, SAO 20575.  The nebula is near a giant molecular cloud that contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to also glow.  The hot central star is thought to have a mass appx 44 x that of our Sun.

With an 8 or 10-inch (250 mm) telescope, both nebulae are visible as extremely faint shells.  A nearby 7th magnitude star to the west of the Bubble hinders observation, but one can view both nebulae using averted vision.  Using a 16 to 18-inch (460 mm) telescope, one can see that the faint nebulae are irregular, and elongated in the north-south direction.

For the AP-er's who visit this page...  This image was captured under Bortle Class 1 skies at the Marathon Motel & Sky Park, located in Marathon, TX.  With only 3.3h integrated image time, it fully realizes the benefits and advantages available when data is collected from dark skies.  For more information, please visit this website...  Marathon Motel & Sky Park﻿

250921 - Sh2-157 "Lobster Claw" + Sh2-162 "Bubble" nebulae