Charles,

Many thanks for your comments on the news note.

The naming of the components is pretty much a free-for-all prior to the
official names coming out of the MPC. In fact, I believe that the MPC
ignore the temporary designations supplied by observers and try to link
the observations purely through astrometry. When there are lots of
objects close together this leads to a lot of confusion.

Within the BAA we tried to use the same letters for the same
condensations running from A for the most sunward back down the tail.
The problem is that other components then appear and A swapped places
with B so everything gets out of order.

MPEC 2020-H28, which came out on April 18, refers to Peter Birtwhistle's
image (attached) and these were the first "official" ones, i.e. C/2019
Y4-A and so on.

Richard's image with the 2.0-m RC shows much more than we were seeing
with 0.25 - 0.25-m class instruments. He tried to keep the same capital
letter designations and so used lower-case for condensations that we
couldn't see. I'm not sure where "FF" comes from though! Perhaps he can
remember.

Component A, which was initially the brightest and the one out in front
was the longest lived fragment. Component B is the condensation that
still survives as the remnant nucleus although MPEC 2020-J16 seems to
have assigned a lot of my later C/2019 Y4-B astrometry to a new
component, C/2019 Y4-E. No idea why.

I agree it is all a bit of a mess but someone will sort it out eventually!

Nick.

On 08/05/2020 23:14, Charles S Morris - cometguy3783 at yahoo.com (via
baa-comet list) wrote:
>   Hi Nick,
> Very well-done and interesting article.  I have a question on the images that detail the various fragment designations (Figure 6).
> What is the significance of the lower-case letters?  'a' is less bright yes, but why A and a?  Is that to indicate that 'a' came from 'A,' which would make sense.  Still, why not simply a different letter?  And what is up with FF?   What happened to E?  Did it fade out?  There looks to be a fragment behind A that isn't labeled.  I know that this isn't your image (not your labels), but Is there some significance to the nomenclature?
> Again, well-done.
> Charles
>      On Sunday, May 3, 2020, 11:21:35 PM PDT, Nick James <ndj@nickdjames.com> wrote:
>
>   Morning all,
>
> I thought I would share with you a news note that I have just prepared
> for the next edition of the Journal of the BAA. It will probably be
> edited for length and content prior to publication but I think it
> demonstrates the amazing work that amateurs were able to do during the
> recent fragmentation event. Many thanks to everyone who submitted
> images, astrometry and photometry to the BAA over this period.
>
> I also attach an animated GIF showing the images included in figure 5
> run together as a movie. The sudden appearance of fragment A on April 9
> and its subsequent drift down the tail is quite dramatic.
>
> Keep observing this comet as it heads in to perihelion. Most large
> professional telescopes are now unable to see it since the elongation is
> small.
>
> Nick.
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