Discovered using the ASERO/Murrell. I was taking 5x60s stacks and using Astrometrica to measure and quickly noticed that 29P was getting much easier to see with a better SNR. Had originally planned to take several such sets separated by 1 hour but events overtook this plan.

4 sets of 5x60s stacks
JD mag Flt SNR ZeroPt Cat Design.
2460394.34874 16.590 R V 37.01 26.284 UCAC4 0029P
2460394.35224 16.314 R V 52.65 26.259 UCAC4 0029P
2460394.37911 14.724 R V 157.05 26.260 UCAC4 0029P
2460394.38261 14.629 R V 166.58 26.303 UCAC4 0029P
—– end —–

So I put a post on the BAA comet group asking for help confirming and emailed Richard Miles to alert him. He asked that I start continuously imaging 29P and measure individual frames as we seemed to be the only ones with clear skies. Many more subs were taken to confirm the comet had increased in brightness from about 16.7R to about 13.7R, a significant outburst. Later on as as we lost the sky to clouds, telescopes in Chile and other parts of the world were able to take over.

Richard requested the first 5 FITS files to determine that the outburst started on the 3rd sub we took. I also sent the remaining subs and Astrometrica files and he produced a preliminary plot using a 3px radius aperture:

All the data are now on the BAA 29P project page.

Alert on the comet group:

ALERT: Strong outburst of 29P/S-W1 discovered by Mark Phillips of the Astro Soc. of Edinburgh (ASE), Scotland
Richard Miles Mar 24 #298
Mark Phillips has only recently joined the MISSION 29P initiative using the ASE’s 0.3-m remote telescope in Spain and has struck very lucky with this discovery of a 13th magnitude outburst of 29P/Schwassmann-Wachmann 1..

This is a particularly important discovery as I expect there to be one or two further strong outbursts during the next 5 days.

The reason is that this event comes 107 days after an earlier very strong outburst, which itself happened 114 days after a previous strong outburst in early August detected by Jean-Francois Soulier.

The time interval corresponds with almost exactly two rotations of the nucleus indicative of a highly-active region on a small fraction of the nucleus surface.

Importantly both these earlier events were followed by at least one further strong eruption within the next 5 days of the first.

We may also see a further step-change in brightness within the next 24 hours as happened in early December.

Well done, Mark!

Further monitoring is much encouraged.

Richard Miles