After my first post on astro photography with a tracking mount, here is another one on my next attempt at wide-angle images. This took place after the solar eclipse on 12 August, which, as some as you probably know, was coincidently the maximum of the annual Perseid meteor shower.
For this session, I thought it would be interesting to try for two objectives. First was the summer Milky Way right across the sky with my new Laowa 8-15mm fisheye lens. The second was to use my 16mm wide-angle lens to try to capture some Perseid meteors and to hopefully show some diverging from their radiant point.
There is only one spot on the Downs that I know of that is accessible by car and is suitable for fisheye imaging. So there is where I setup for taking shots from about 23:00 as astronomical twilight ended and the night officially started. I again used the astro-modified Canon RP, but this time with the fisheye lens set on 8mm, to give a circle showing the full 180 degree sky. This I mounted on the iOptron Sky Guider Pro tracking mount, so I could take 2min exposures for about 1hour (i.e. 30 "subs" in total). The main limitation here is the light pollution which is worst to the north and east, better to the south.
After stacking and background removals etc, I ended up with the image below. I've suppressed as best I can the light pollution around the edges. The astro-modified Canon RP has again produced some nice detail and colour in sections of the Milky Way. The Lagoon nebula, M8, can even just be seen as a tiny red spot very close to the southern horizon (about 8 o'clock on the image below).
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| Milky Way image obtained using a 180 degree fisheye lens © Stephen Burch |
In parallel with the fisheye imaging for the Milky Way, I setup my 16mm WA lens attached to my "birding" R5 on a static tripod (no tracking). This limited me to 8 sec exposures which I took at 10 sec intervals. This I just left stopping every so often to change the camera’s view to approximately follow the radiant point, as it rose in the sky from its starting point low in the light polluted north east sky. After the better part of 3 hours, I had accumulated almost 1000 shots! Even the ones with the highest radiant point were significantly degraded by light pollution.
By looking through the collection of about1000 shots, I eventually managed to spot about 20 meteors, i.e. about one every 50 shots or 1 every 6.7 mins! I may well have missed a few as its not easy to see rare meteors in an image full of stars and many aeroplane and satellite trails!
Below is a composite image showing all the detected meteors superimposed (and aligned) on top of a stacked image of the Milky Way and stars. I was surprised how colourful all the Perseid meteors were, with red at the start of each trail which turned to green towards the end. The odd sporadic meteor (see short trail near the top of the image, in the left side of the Milky Way) did not show such colour.
The image below also clearly shows the divergence of the meteors from the radiant position which was below Cassiopeia (although it is difficult to discern that constellation in the image below).
Also visible in the Andromeda Galaxy, M31 - the angled elliptical blob to the right of the Milky Way near the centre of the image.
So quite a late night but well worthwhile!
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| Composite image showing 20+ Perseid meteors superimposed on a stacked image of the Milky Way taken from the same sequence of photos. Better viewed large on a black background by clicking on the image. © Stephen Burch |
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