3-Colour Imaging NATIONAL SCHOOLS' OBSERVATORY

Overview  Understanding Colour Images  Colour Cameras and CCDs  Colour Components and Colour Images  Recreating Colour Images  A Colour Puzzle  Astronomical Cameras and Filters  Representative Colour Images  3-Colour Images Colour image of a Spiral Galaxy NATIONAL SCHOOLS' OBSERVATORY

How red, green and blue mix to make other colours NATIONAL SCHOOLS' OBSERVATORY

NASA The CCD on the Liverpool Telescope is located in the RatCam Detector. CCD Chip NATIONAL SCHOOLS' OBSERVATORY

Colour Cameras and CCDs A colour CCD showing pixels in grey and the red, green and blue filters over them. NATIONAL SCHOOLS' OBSERVATORY

Intensity through Red Filter Intensity through Green Filter Intensity through Blue filter Red filtered image coloured Red Green filtered image coloured Green Blue filtered image coloured Blue Red, Green and Blue images combined NATIONAL SCHOOLS' OBSERVATORY

Can you work out the colour of the sweets at each of the labelled positions in the bottom right image? NATIONAL SCHOOLS' OBSERVATORY

The Answer! NATIONAL SCHOOLS' OBSERVATORY

RATCam (CCD camera) on the Liverpool Telescope Astronomical Filters as used on a Research Telescope NATIONAL SCHOOLS' OBSERVATORY

Part of M17. Combination of i', H-alpha, g' and r' observations. © 2008 A. Newsam & Robert Nickson Jupiter © 2005 A.Newsam & the LT project. NATIONAL SCHOOLS' OBSERVATORY

M20. Mosaic of r', V and B observations. © 2008 A.Newsam, Bryn Davies & the LT project. The image of M20 (above) is a combination of 3 filters that are broadly red, green and blue. This is a “representative colour” image. NATIONAL SCHOOLS' OBSERVATORY

The Eagle Nebula (a mosaic). © 2004 A. Newsam & the LT project.. NATIONAL SCHOOLS' OBSERVATORY

Activities Try producing a 3-colour image in LTImage using the sets of images supplied with this workshop. You can choose one or more of the following sets: Ferry Castle M20 - Trifid Nebula M16 - Eagle Nebula M1 - Crab Nebula NGC2776 (galaxy) All of the images are provided in the FITS format that LTImage recognises. Some will require scaling, whilst others will not. All will require a variable amount of alignment. Instructions for using LTImage are on the NSO website. You can use Go Observing to get your own sets of red, green and blue images from the Liverpool telescope. You can then use the NSO’s LTImage software to combine the 3 observations to make your own 3-colour images. Image being aligned in LTImage Requesting a 3-Colour Observation in Go Observing NATIONAL SCHOOLS' OBSERVATORY