Nick,

Can you update your plot?

It looks like another disruption event occurred on 2020 May 08.1±0.3 that
ejected a cloud of debris sunwards at speeds of about 50-100 m/s. Such an
energetic event must have involved considerable force / internal pressure so
the nucleus may very well have broken up. Eight days later, the nuclear
magnitude has faded by about 60%.

Images attached.

The timing fits in perfectly with your attached email from a week ago!

Richard

----- Original Message -----
From: "Nick James" <ndj@nickdjames.com>
To: <baa-comet@simplelists.com>
Sent: Saturday, May 09, 2020 8:35 AM
Subject: [BAA Comets] C/2019 Y4 (ATLAS) sudden brightening

> Morning everyone,
>
> Up until yesterday the central region (11 arcsec radius) of C/2019 Y4
> has been brightening at around 0.05 mag per day but last night it had
> jumped by a whole magnitude compared to the night before (May 7.9 vs May
> 8.9). The attached plot is from my astrometry with a 0.28-m, f/10 SCT in
> Chelmsford.
>
> Terry Lovejoy, via the CometWatch FB group, reports a similar sudden
> increase between May 8.12 and May 9.12 using the iTelescope T11 system
> in New Mexico.
>
> With all the excitement over C/2020 F8 (SWAN) please remember to keep
> observing Y4 for as long as you can.
>
> Nick.
>
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