M74 is a face-on spiral galaxy in Pisces. It was discovered by Pierre Méchain in 1780 and Messier added it to his catalogue in the same year. It is a beautiful galaxy seen in a large telescope but it is small (subtending only 10 arc-minutes) and rather faint. Its integrated magnitude is 9.4 but its surface brightness is only 14.2. This makes it a difficult object for the amateur. It is about 32 million light years away.
Supernova 2013ej was first detected on 25 July 2013 by the Lick Observatory Supernova Search. Of course it actually exploded 32 million years ago and I think it is sobering to realise that, when Man emerged as a species on the plains of Africa, the photons that enabled us to see the explosion had completed 99.99% of their journey to our telescopes. It is believed that this supernova was detected within a day or two of the first photons arriving here, so it will be possible to follow its development from a very early stage. It is a Type II supernova which results from the collapse of a star with a mass greater than about 8 times that of the Sun. Unfortunately I do not have an image of M74 prior to the appearance of the supernova, and so I exposed the pictures to bring out the galaxy and this has resulted in the supernova being over-exposed, so I cannot estimate its magnitude from these pictures. However estimates of the magnitude on an on-going basis can be found at the Rochester Astronomy Group.
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I do not have an image of M74 before the supernova exploded so I am very grateful to Peter Vasey for his permission to reproduce his beautiful image of M74 taken in 2006. Although the scale of Peter's picture is somewhat greater than mine, you can see that the star arrowed in my mouseovers was not present in 2006. I have reduced Peter's image by a factor of two to compare better with my images. You can find the original image or an even larger version on his web site. |
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This is my first image of M74, taken under less-than-ideal conditions, just 10 days after the discovery of the supernova. This picture was taken when the Sun was only 15° below the horizon and M74 was 43° above it and in the more-polluted part of my skies. The supernova is indicated by the arrow in the mouseover. Date and Time: 4th August 2013 02:09 to 02:19 UT UT Camera: Starlight Xpress MX716 Telescope: LX200 with 0.33 focal reducer (focal length 800 mm) Capture: star_mx7. 60 sec exposure, 10 frames plus dark frame. Processing: star_mx7. Each frame enhanced by factor 25. Irfanview. conversion to .bmp format. Bespoke software. Subtraction of dark frame. Registax6. Stacked all frames, Gaussian wavelets Scheme 2. | ||
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Two more pictures taken, respectively, on 6th and 13th August 2013. Capture and processing details as above. | |
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