28 hours of integration
88 x 400' Ha (9.7 hours) ISO 1600
93 x 400' OIII (10.3 hours) ISO 1600
96 x 300' Lum (8 hours) ISO 800 / 1250 respectively
Plus numerous Dark, Bias and Flat calibration frames
Stacked in DSS; post-processing and Photometric calibration in PixInsight

Project started around mid-January, but due to the difficulty of imaging this DSO in particular, it wasn't possible to accumulate more than 5 or 6 hours per week or so only when sky was clear and transparency was reasonable! It doesn't usually reach high enough in the sky from this latitude so it dips below the horizon pretty fast!

Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 2-308 it lies some 5,000 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a Full Moon. That corresponds to a diameter of 60 light-years at its estimated distance. The massive star that created the bubble, a Wolf-Rayet star, is the bright one near the center of the nebula. Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution. The windblown nebula has an age of about 70,000 years. Relatively faint emission is dominated by the glow of ionized oxygen atoms mapped to a blue hue. Presenting a mostly harmless outline, SH2-308 is also known as The Dolphin-head Nebula.