Comet C/2023 H2 Lemmon

[Ross Wilkinson]

This comet was discovered by the Mount Lemmon Survey back in April and is currently a ninth-magnitude object in Ursa Major - so it's very low above the Northern horizon.

I managed to catch it briefly last night: although I captured 50 minutes' worth of data, the last half was marred by increasing haze.

So that's a stack of 25x 1-min with my Mx716 on the C8 operating at f/3.5.

This comet is still brightening - it will be tracking through Bootes and Hercules in the coming weeks and is expected to peak at 7th magnitude in mid-November.

[Ross Wilkinson]

In fact last night was my next opportunity to catch it - and even then I had to grab my opportunity before it disappeared below the roof of the house next door!

I hadn't anticipated just how quickly it would be tracking across the sky (27 arc-minutes per hour) - until I noticed that it was trailing on my first 60-second image. So I switched to 30-sec exposures, and managed to collect forty of these whilst keeping it in frame.

I tried to do another sequence after re-aiming the 'scope, but this was soon halted by patchy cloud and the neighbours' roof.

This is my stack of the 40 subs:

Clearly I should have used another 'scope with a wider field of view!

This was processed in IRIS, but then I subsequently tried using SiriL to create an MP4 animation:

https://www.youtube.com/watch?v=G-lKTp-_W-M

[Ross Wilkinson]

As we had another consecutive clear night (when did that last happen?), I set up my colour imaging system: the Sony NEX5R on my Starwave 80ED, operating at f/4.8. With a field of view of more than 3x2 degrees I could keep it in frame much longer.

That's a stack of 81x 30-sec, processed in SiriL and GIMP.