Target
Sh2-157 — The Lobster Claw Nebula
Frame / Rev
009 / A
Integration
28h 45m
Catalog
Sh2-157
Class
Emission nebula
Constellation
Cassiopeia
Distance
11,000 ly
Coordinates
RA 23h 16m 17s · Dec +60° 32′28″
Palette
SHO
Sessions
6 nights · Sep 2025
Sky
Bortle 9
Target & processing
Stretching across the rich Milky Way of Cassiopeia, SH2-157 forms a striking arc of ionized gas, with the dark LBN 1036 region cutting into its eastern edge. Part of the larger W5/W4 complex, this faint nebula reveals a landscape where glowing hydrogen, dust, and young stellar associations intertwine.
My first target spanning across more than 2 nights, with a significant amount of integration time.
This is where I realized that more integration time meant less fighting against noise in processing.
Note to self
Although I liked it when I made it, with more experienced, I found the processing too harsh. So I decided to reprocess it in 2026 (with the same data).
Per-filter integration
Hα 18.6% · 5h 20mSII 24.1% · 6h 55mOIII 47% · 13h 30mR 3.5% · 1h 00mG 3.5% · 1h 00mB 3.3% · 1h 00m
KeptRejected at integration
Equipment
Optics
William Optics RedCat 51 · 250mm f/4.9
Camera
QHY MiniCam8M · IMX585 · 2.9µm / px
Filters
XiMei 7nm Hα / OIII / SII + XiMei Broadband R / G / B
Mount
ZWO AM3 harmonic, no counterweight
Guiding
Uniguide 32mm + ZWO ASI120MM Mini
Control
Mele Quieter 4C · NINA + PHD2
Site
Montréal, QC · Bortle 9 · 45.5° N
Adjacent frames
