Cygnus (The Swan) constellation is filled with hydrogen clouds that are ionized and radiate massively in red light (656nm that is hydrogen alpha line). Some time ago I shot the IC1318 Butterfly Nebula but in fact it was only a part of it (actually parts B and C). Now part A is going to be presented. The whole IC1318 nebula complex is about 3700 light years away from us. Most of nebulas can be described as emission or reflection ones. Reflection nebula is a dust cloud. If there is a star nearby it reflects star light. If there is no star – the dust cloud may be detected as opaque clouds blocking light from objects behind them.
Emission nebula on the other hand emits spectral light radiation from ionized gas. In case of IC1318 it is ionized hydrogen. Young blue stars in this nebulas emits large amount of UV light that ionize the surrounding gas. This giant, red hydrogen nebulas are called HII regions.
The picture above has been exposed over two August nights. The total exposure time was 7.5 hours using Canon 450D camera modded for red light. GSO 6″ F/5 newton telescope was equipped with 0.9x field flattener and worked with effective focal rafio of f/4.5. In spite of such long exposition the amount of detected red light is not remarkable, because in DSLR cameras only one out of four pixels detects red light.
