SH2-308 Blue Dolphin Nebula
The SH2-308 Blue Dolphin Nebula is an H II region composed of ionized hydrogen. It's distance from Earth is unknown but believed to be about 4,500 light-years. The nebula stretches about 60 light-years across. Although very faint, it responds well to an Oiii filter when imaging. There is also a red portion that can be seen with an Ha filter, but for this shot I decided to concentrate on just the blue portion. North is at the bottom-left.

Scope/Mount: TS-Optics PhotoLine 130mm F7 APO Refractor with Astro-Tech AREDT30 Focal-Reducer/Field-flattener, Celestron CI-700 Mount
Camera: ZWO ASI1600MMC monochrome with ZWO LRGB filters and Antlia 3nm SHO filters
Guiding: QHY5L-IIM through Orion Thin OAG, PHD guiding software
Exposure: Oiii: (36) 300 secs @ gain = 300, RGB: each channel (10) 120 sec @ gain=200
Software: Nebulosity, Pixinsight
Comment: 01-13-2026, Tierra del Sol, CA, bad seeing, palette = OOO plus RGB for stars.