At last, with a forecast for a clear evening, I headed out to a local spot at the foot of the Downs. This place has a good horizon to the north and west, although the skies can hardly be described as dark with the glow of a distant Swindon visible on the westerly horizon, with other places all around.
I tried taking exposures with my old EF mount macro 100mm f2.8 lens on my Canon R5. To avoid star trails on an untracked mount, I was limited to a 3 sec exposure time. The interval timer on the R5 allows a maximum of 99 shots to be taken in a sequence, so that is what I collected. I also took some "flat" and "dark" calibration frames.
Back on the computer I loaded all these images into DeepSkyStacker which is a free download. After a lot of fiddling around with Photoshop after stacking, I eventually ended up with this image, which shows both tails reasonably clearly. For the best view, click on the image so that it opens in its own window, surrounded by black and then turn the lights in your room off or down.
The length over which the narrow, straight ion tail can be seen was surprising - it reached the top edge of the field of view,
Maybe by the time the next comet comes along I will have invested in a tracker mount to allow massively increased exposure times and hopefully better final results. Although I fear that the local light pollution will then quickly become the limiting factor.
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| Comet C/2025 A6 (Lemmon) © Stephen Burch |
