Tuesday 4 December 2018 — ASTROPHOTOGRAPHY
Not a large spider, but an astonishing area of the night sky. The image shows the area in the constellation Dorado (the Dolphin fish or Swordfish), around the Tarantula Nebula, a huge area of gas and dust where stars are being formed, which is in the Large Magellanic Cloud, a nearby galaxy outside our Milky Way, and closely associated with it. There are a lot of firsts for me in this image. It is the first time I have imaged an object which is simply not visible from the UK. The Magellanic clouds are too far south in our sky ever to rise here. It is the first time I have imaged a nebula that is not in our galaxy and the first time I have used a telescope to make such a wide-angle image. It is also the first time I have imaged using a monochrome sensor and filters. It deserves a close look (click on the image to see full size, or to save).
I was amazed and a little awestruck when I first saw the images from the telescope. I knew it would be wide angle, but had not really expected the area to be so rich and the nebula to be so prominent within it. The main nebula is in the centre of the frame, with other areas of gas and dust around it. Across the lower right there is the central “bar” of the Magellanic cloud, which is thought to be a barred spiral galaxy, disrupted by interaction with the the smaller Magellanic Cloud galaxy and our own Milky Way. Just looking over the image, I could see a number of star clusters, nebulae and other interesting concentrations. I was able to automatically annotate the image (drawing data from the Vizier catalogue system) and quickly lost count of how many listed objects there are within the image (click on image for full-size).
I plan to revisit this area, using telescopes with a narrower field of view to show more detail on individual objects, or small groups of them. Before I do that, though, I will use the very wide angle imager to look at some other very interesting areas of sky.
Oh, and the “tarantula” name? It is said to come from the more or less symmetrical loops of gas looking like spiders’ legs.
I made this image with telescope 12 of iTelescope. This is a 106mm f5 refractor sited in Siding Springs Australia and fitted with a large sensor specialist camera. The colour image was made from 4 two-minute exposures through a luminance (plain) filter and 2 two-minute exposures each through red, green and blue filters to capture colour. I processed it in PixInsight software. The annotated image is a single luminance frame (2 minute exposure) without processing (just stretched) with the PixInsight annotation script applied.