Chris Heapy

Macclesfield, UK

The telescope used was a TeleVue NP127is refractor mounted on a Losmandy G11 equatorial mount, and guided with a TV Pronto guidescope and SX Lodestar guidecamera. The CCD camera was an Atik490EX operating at 1×1 binning, equivalent to 1.1 arcsec/pixel. All subframes were 20minutes long, 10 subs per channel for a total of 10 hours exposure. Data was aquired over several nights during Sept/Oct 2014 from my suburban back garden observing site.

IC410 is an emission nebula in the constellation of Auriga. It is some 1200 light years distant and spans approximately 100 light years across. At the centre of the nebula lies NGC1893, a cluster of young bright and energetic stars, the powerful radiation of which has hollowed out the primeval cloud of dust and gas, driving outwards and eroding it into an irregular boundary. A notable feature of this nebula are the two ‘Tadpoles’ as they are commonly called, which consist of denser clumps of material together with embedded stars. These areas have resisted the outward flow to a greater extent causing the gas and dust which is being driven outwards to flow around them thus producing the remarkable shapes that can be seen here. This image is is a narrow-band composite of Hydrogen-alpha and Sulphur II emission wavebands (shown in browns and yellows) together with a remarkably strong Oxygen III waveband shown as an area of blue. All three wavebands lie within the red portion of visible spectra but here they have been mapped to Green, Red, and Blue (respectively) to better show the contrast in relative distribution. This colour combination is known as the ‘Hubble Palette’ or HST Palette (because it is primarily used for images produced by the Hubble Space Telescope). This is a fascinating object for me, the 3D appearance of the hollowed-out central portion shown in blue contrasts sharply with the boundary of brown dusty material, and overlaid on top are back-lit dark nebulae consisting of more obscuring dust and gas.