Charles,
 
I confess being responsible for the labelling.
 
The lettering is not random but follows a specific methodology, which is this:
 
1. Condensations as they appear are labelled in capitals (A, B, C, etc.) in order of their position - essentially in this comet in order of Right Ascension.
 
2. When a new condensation appeared behind another I gave it a double letter in capitals, hence 'FF' appeared downtail of F.
 
3. Then we had a couple of new condensations appear ahead of A  and of B and these then became lowercase letters, 'a' and 'b'
 
The attached shows the evolution in the labelling as seen using the 2.0-m Faulkes Telescope North.
 
Condensations rarely last more than 5 days and some only stick around for 1-2 days because they fade to below the detection limit of the telescope.
 
Hope this helps,
Richard Miles
 
----- Original Message -----
From: Charles S Morris - cometguy3783 at yahoo.com (via baa-comet list)
To: baa-comet@simplelists.com
Sent: Friday, May 08, 2020 10:14 PM
Subject: Re: [BAA Comets] BAA Journal news note on C/2019 Y4 (ATLAS)

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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