Deep Space Collection # 3. Dolphin Head

Sh2-308, commonly known as the Dolphin-Head Nebula, is an H II region located near the center of the constellation Canis Major. It is a bubble like region composed of ionised hydrogen surrounding a star that's in the brief, pre-supernova phase of its stellar evolution. The nebula is about 5,000 light-years away and 60 light years across. About the Deep Space Collection: Shot entirely with my rooftop telescope from the urban skies of Buenos Aires, the Deep Space Collection features many objects observable only from the southern hemisphere. All images in the collection were shot using individual narrowband filters which cut off most of the light and allow only very specific wavelengths to pass (the light emitted from ionized hydrogen, oxygen and sulfur), making it possible to photograph deep space objects even from the highly light polluted skies of the city. The images from each separate filter are then processed individually, combined and mapped to RGB channels for a final color image. Two different color mapping palettes were used in this collection: SHO, where sulfur is mapped to red, hydrogen to green and oxygen to blue in what is referred to as "Hubble Palette" processing (as used in the images the famous space telescope) and HOO, where hydrogen is mapped to red, and oxygen to blue and green.