Morning all,

These are what my observations have calculated for April 3,6,9,10 with all variables as constant as possible on very clear mornings. Conclusion is that there was an eruption that increased the brightness 4 times from April 3 to April 6, then on April 9 and 10 the comet had faded by a factor of 2 times in brightness from my observed peak of magnitude 8.4 on the morning of April 6. If I read Nick's data correctly he has observed the sharp rise in brightness (I did not get to observe the comet on April 7 and 8) and now the decline in brightness the last several mornings. Rather large moves in brightness for such a short period of time. The images are all the same field of view, the images show what the comet has been doing the past week in a 3.5 arc minute aperture diameter.

Cheers, Mike.

> On 04/10/2025 10:06 PM -07 Nick James <ndj@nickdjames.com> wrote:
>
>
> Morning all,
>
> This comet appears to be fading. I imaged it this morning (April 11.14)
> and I get a total magnitude of 9.6 and coma diameter of 2.3′ using
> comphot on the green pixels vs Gaia DR3. My last measurement was on
> April 9.14 when I got mag 8.6 and 3.0′. Some of this will be the
> brighter sky due to the Moon but the comet is also fainter in my 9
> arcsec aperture photometry. Does anyone have any recent observations?
>
> The attached plot shows 9 arcsec photometry from myself, Denis Buczynski
> and Peter Carson. Shortly after discovery the magnitude rose rapidly but
> it is now fading. Total magnitudes are shown on the COBS lightcurve here:
>
> https://cobs.si/comet/2619/
>
> There is a huge amount of scatter on these from different observers. To
> see a trend you need to look at the results from a single observer using
> the same equipment and method. Mine are here:
>
> https://cobs.si/analysis/?comet=2619&from_date=&to_date=&observation_type=V&observation_type=C&plot_x_value=1&plot_y_value=1&fit_option=1&observer=195&association=&country=&compare_values=filter
>
> These appear to tell quite a sorry story but we need to keep observing
> this comet to see what it will do.
>
> Nick.
>
>
> On 07/04/2025 10:12, Peter Tickner - peter.tickner1472 at btinternet.com
> (via baa-comet list) wrote:
> > Hello Nick
> >
> > In the end I used the second set of measurements I’d obtained and by some miracle the comet appeared dead centre of my image field.  But that was the only good news. It didn’t clear my local obstructions until twilight was well advanced so all I have is a faint blob with a bright background and three brighter stars showing through.
> >
> > Peter T
>
> To unsubscribe from this list please go to https://lists.simplelists.com/subs/