The Phantom of the Opera Nebula (Sh2-173)

Southeastern MA - September/October 2026

Camera: Canon Ra

Telescope: William Optics GT81 IV

Optics: Stellarvue SFFX1 Flattener

Mount: Sky-Watcher EQM-35 Pro

Guide: ZWO ASI120mm Mini + William Optics 50mm uniguide scope

Filter: Svbony SV220 7nm Ha/OIII

Control and Guiding: Mele Quieter 4C running N.I.N.A., PHD2, Green Swamp Server

Exposure:

Ha/OIII: 300s × 258 subs (~22 hours)

Broadband Stars: 30s × 240 subs (2 hours)

ISO: 1600 (Narrowband) / 400 (Broadband)

Calibration: Temp-matched Darks, Flats, Biases

Siril: Channel extraction, GraXpert denoising, Cosmic Clarity Sharpen, StarNet++ star removal, Modified HOO PixelMath combination, statistical stretch

Photoshop: Selective color adjustments, background contrast curves, and broadband RGB star recombination.