Hi Denis,

 

The observations are not a good fit to a linear type light curve, which would be expected if the comet was going to be significantly brighter post perihelion.  It could always outburst, but that would be a different story.

 

I don’t think scattering is going to play a part for this comet as the phase angle is already quite large and increasing.

 

The tail geometry is pretty good, with it being perpendicular to the horizon in the morning sky as it first emerges into darker skies.  In the evening sky it is initially inclined, but nearly perpendicular by mid month.  By extrapolation (using geometry and total magnitude) from the length reported by Michael Mattiazzo on June 10, the tail could be 10 degrees long on July 6.  However bearing in mind the notorious fickle nature of comets I wouldn’t bet on it!

 

Regards,

 

BAA Comet Section visual observations co-ordinator

https://www.ast.cam.ac.uk/~jds/

 

 

 

From: baa-comet@simplelists.com <baa-comet@simplelists.com>
Sent: 02 July 2020 15:52
To: baa-comet@simplelists.com
Subject: Re: [BAA Comets] 2020 F3 (NEOWISE)

 

Hi Jon,

Thanks for the update. What are your thoughts of a post perihelion surge in brightness? Also is there is prospects of a forward scattering enhancement? Lastly has this comet been releasing much dust pre-perihelion, as it is a strong showing of the dust tail that would give the best view for us. Nice to have a bright comet to have a chance of observing especially in the dawn sky.

Best wishes

Denis





------ Original Message ------
From: "Shanklin, Jonathan D." <jdsh@bas.ac.uk>
To: "baa-comet@simplelists.com" <baa-comet@simplelists.com>
Sent: Thursday, 2 Jul, 20 At 11:40
Subject: [BAA Comets] 2020 F3 (NEOWISE)

2020 F3 (NEOWISE) looked in good shape as it passed through the SOHO C3 field in late June. Rough estimates of its magnitude suggest that the comet could now be -1 magnitude, and its elongation from the sun is increasing. The southern part of the UK is at almost the optimum latitude for an early recovery of the comet post perihelion. Visual observers may have to wait until the early morning of July 6, though within a few days of that the comet will also be visible in the very late evening. Imagers may be able to pick the comet up earlier, perhaps as early as perihelion on July 3. The only problem is the weather - it doesn't look as if there will be adequately clear skies over the next few days.

The latest observations of 2019 U6 (Lemmon) suggest that it is fading a little more quickly than expected from a standard light curve. It may well be 9th magnitude by mid July when it gets far enough north to be seen from the UK.

Remember however that comets rarely continue to follow the light curve indicated by past observations, so going out and observing is the best way to find out how bright these comets actually are.

Do send me your visual or visual equivalent observations in ICQ format - either directly to me, or via COBS https://cobs.si/ The advantage of using COBS is that your observations will be correctly formatted. Provided you have registered with COBS as a BAA observer I can collect your observations, otherwise please extract them yourself and send them on to me. Those observers who send me immediate updates are particularly thanked as this allows for frequent updating of the Section visual observations web page at the address below.

Regards,

BAA Comet Section visual observations co-ordinator
https://www.ast.cam.ac.uk/~jds/



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