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Last week I was hunting through our archive of public observations. I wanted to find observations that, together, would form a larger image. My plan was to test out some command-line software - Montage - that can automatically combine FITS files into mosaics. Montage is created by the good folks at NASA's Infrared Processing and Analysis Centre (IPAC) and uses the coordinate information (WCS) stored in the FITS files. Montage can calculate image overlaps and can then attempt to match up the backgrounds of the individual images to make a pretty mosaic.
Following one of the Montage examples I managed to create this mosaic of the Orion Nebula from images taken by Shoeburyness High School using the Faulkes Telescope Project. After that first success I discovered a large number of images of NGC6960 taken by Brockenhurst College and had a go at a mosaic of the Veil Nebula - the remants of a supernova that exploded thousands of years ago.
The day after my mosaic attempts I was pleasantly surprised to receive a phone call from Alex Crutchley - a lecturer at Brockenhurst College. Alex, along with his A-Level physics students (who were also doing a GCSE in astronomy at the same time), had taken the original images in 2010 using Faulkes Telescope North. His aim was to demonstrate that different colors can be used to highlight the different chemical structures present in the supernova remnant. As a result, Alex and his students had taken 31 frames in each of three filters (H-alpha, H-beta, and OIII), each with exposures of 120 seconds, resulting in a combined exposure time of 186 minutes. During our conversation Alex told me that he had processed all the images using Photoshop CS4 and the FITS Liberator plugin but had become busy at work and had forgotten about it. My mosaic had reminded him so he dug it out and he has kindly agreed to share the results here. I think you'll agree that results are quite stunning.
Alex has made several different representative color images and I've just shown two above. In reality, H-alpha is red, H-beta is blue and OIII is green, but these shifted-color images still highlight the different structures of hydrogen (H-alpha/H-beta) and oxygen (OIII) present in the remnant whilst keeping the stars looking fairly white. They have also been rotated 90 degrees because, as Alex points out that, this makes it look like the star 52 Cyg (the bright star near the centre of the mosaic) is the Sun setting below a band of clouds on the horizon - a composition that is quite pleasing to the eye. The entire supernova remnant is roughly 3 degrees across (6 times the angular diameter of the Moon with a centre to the east of this segment) so there is plenty more still to image if anyone wants to give it a go!
A huge thanks to Alex and his students for letting us showcase these images. I think they are a great example of the results that can be achieved when telescope time is used for a coordinated project. They also hint at what can be found by exploring our ever-expanding archive. Go explore.
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