The Rosette Nebula 21st March 2009

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The Rosette Nebula is a much photographed emission nebula in the constellation of Monoceros. Although the dominant gas is hydrogen emitting hydrogen alpha light there is plenty of oxygen showing as the blue OIII regions towards the center and smaller amounts of sulpher, SII, particularly towards the peripheries. Both SII and Ha are in the red part of the spectrum whereas OIII is actually teal in colour. To produce a colour image images from the 3 narrowband filters have to be mapped to "false" colour channels of red green and blue. The choice is fairly arbitary. By mapping SII to red, Ha to green and OIII to blue the channels at least correspond to there energy levels within the spectrum. This is the palette developed for the Hubble Space Telescope images.

This image was captured in challenging conditions. The atmosphere was quite misty and the Rosette was quite low down in the west. After 2 hours the mist became too dense and the session had to be ended.

Scope: Takahashi FSQ 106

Camera: QSI 532

Filters: Astronomik 13nm Ha OIII and SII

Exposure details: Ha 5x400 secs, OIII 6x400 secs, SII 7x400secs

Captured and combined in MaximDL. DDP, scaling and colour combine in Maxim and final processing in Photoshop.