[BAA Comets] First outburst of Comet 29P in 2015 - Caught on the rise!
Richard Miles
rmiles.btee at btinternet.com
Sat Feb 7 23:35:41 GMT 2015
Wow Kevin !!!
Thanks for your recent observations.
You might not realise it but your observation of 2015 February 02.75
happened to have been made whilst 29P's outburst was still developing. It's
very rare to catch it on the rise like this.
Let's put it in perspective.
My analysis of amateurs' observations of this comet since 2002 August
(>18,000 of them) indicate a mean rise time for a typical outburst of just
1.7 hours. So out of many thousands of measurements, only 7 have coincided
with the rising branch of its lightcurve. Your observation, namely:
29P 02/02/2015 17:58:54 14.76 14.63 14.73 33.5 16.9 D90
is the 8th such one. The comet would have been entirely stellar in
appearance in your image.
Well done.
My estimate of the outburst mid-time had been 2015 Feb 03.07 +/-0.55. I
could tighten the uncertainty in this estimate once I extrapolate the coma
expansion back in time, but, thanks to your observation we now know this
took place on 2015 Feb 02.73 +/-0.03.
-------------
CATCHING A COMETARY OUTBURST?
I was thinking that it might be worthwhile for amateurs to try to record the
rising branch of an outburst of 29P. Now there's a challenge!
No-one has ever got anywhere near achieving this, mainly because observers
only take say 10 minutes or so of images. Ramon Naves (213) and César Piret
(J46) did overlap observations on 2007 December 29/30 spanning almost 0.07
days as 29P approached maximum - that's the nearest anyone has got to it.
I think the initial rise is extremely rapid and then it approaches maximum
light in an exponential fashion. But that is part speculation from me based
on the fact that, since 2002, only 1 out of 7 observations during the rising
branch of its lightcurve has coincided with the first 50% change in
magnitude. We need to find out what the reality is through a change in
observing method where we can track it from its trigger event. Only amateurs
are in a position to achieve this goal.
So would some keen observers of 29P consider changing their approach by
observing it intermittently, I wonder? Say once per 30-60 minutes, several
times per night for say a minimum of 3 hours. Eventually, given enough
observations, Comet 29P would be caught starting to outburst. Maybe a
campaign would be worth starting in say 2017 when the comet is better placed
for observers.
I would of course like to help by providing a prediction of times when it is
more likely to outburst so that coverage can be stepped up in this way. But
unfortunately the rotational axis of the nucleus is tilted somewhat and this
induces a seasonal effect in its behaviour. For the last 4-5 months the
activity of the nucleus indicates that a new season has begun, in which the
distribution of its outbursts has changed and can now no longer be
predicted. However, by 2016 or 2017 when its latest outbursts have been
better characterised, predictions may be possible once again.
Richard Miles
BAA
----- Original Message -----
From: "Kevin Hills kevinhills at me.com [comets-ml]"
<comets-ml at yahoogroups.com>
To: <comets-ml at yahoogroups.com>; "'BAA Comets discussion list'"
<comets-disc at britastro.org>; <asvcometsection at yahoogroups.com>
Sent: Saturday, February 07, 2015 5:32 PM
Subject: RE: [comets-ml] Re: [BAA Comets] First outburst of Comet 29P in
2015
> Sorry for the delay in responding Richard, I have been travelling (work,
> not pleasure).
> I have found it a challenge getting reliable data over the past few weeks
> because the comet is in a very crowded star field, but I believe that the
> following measurements are okay and will hopefully help you.
> Multibox:
> 10x10 20x20 30x30 40x40 50x50 60x60
> SNR SB COD
>
> OBJECT DATE TIME +/- +/- +/- +/- +/-
> +/- N FWHM CAT
>
> ------------ ---------- -------- ----- ----- ----- ----- ----- -----
> ---- ---- ---
>
> 29P 21/01/2015 18:34:27 16.95 16.51 16.60
> 7.1 17.5 D90
> 29P 21/01/2015 18:34:27* 0.15 0.20 0.20
> 5 4.3 CMC
>
> 29P 30/01/2015 18:43:33 16.75 16.32 16.38
> 5.3 18.0 D90
> 29P 30/01/2015 18:43:33* 0.17 0.31 0.31
> 4 3.8 CMC
>
> 29P 02/02/2015 17:58:54 14.76 14.63 14.73
> 33.5 16.9 D90
> 29P 02/02/2015 17:58:54* 0.14 0.14 0.14
> 5 4.3 CMC
>
> 29P 04/02/2015 17:50:24 13.76 13.55 13.65
> 48.7 16.8 D90
> 29P 04/02/2015 17:50:24* 0.05 0.03 0.03
> 5 3.7 CMC
>
>
>
> kPhot (for COBS):
>
>
>
> IIIYYYYMnL YYYY MM DD.DD eM/mm.m:r AAA.ATF/xxxx /dd.ddnDC /t.ttmANG ICQ
> XX*OBSxxf InT APERTURcamchip SFW C ## u.uu xx.x PIXELSIZE
>
>
>
> 29 2015 01 21.77 C 16.5 MC 40.6Y 9a120 0.2 ICQ XX
> HILaaI C 0.22mST1 K10 AFo 5 P5 0.15 1.4s 1.4
>
> 29 2015 01 30.78 C 16.3 MC 40.6Y 9a120 0.2 ICQ XX
> HILaaI C 0.22mST1 K10 AFo 5 P5 0.17 1.4s 1.4
>
> 29 2015 02 02.75 C 14.6 MC 40.6Y 9a120 0.2 ICQ XX
> HILaaI C 0.22mST1 K10 AFo 5 P5 0.14 1.4s 1.4
>
> 29 2015 02 04.74 C 13.6 MC 40.6Y 9a120 0.2 ICQ XX
> HILaaI C 0.22mST1 K10 AFo 5 P5 0.05 1.4s 1.4
>
>
>
> With kind regards,
>
> Kevin
>
>
>
>
>
>
>
>
>
>
>
> From: comets-ml at yahoogroups.com [mailto:comets-ml at yahoogroups.com]
> Sent: 4 Feb 15 10:54
> To: BAA Comets discussion list; comets-ml at yahoogroups.com;
> asvcometsection at yahoogroups.com
> Subject: [comets-ml] Re: [BAA Comets] First outburst of Comet 29P in 2015
>
>
>
>
>
> Confirmed in LCOGT images taken from South Africa and from Chile:
> http://britastro.org/asteroids/29P_2015Feb3-4_thumbnails.jpg
>
> R Magnitude measured at 13.85 +/-0.04 in a 7.5 arcsec diameter aperture.
>
> Richard Miles
> BAA
>
> ----- Original Message -----
> From: "Richard Miles" <rmiles.btee at btinternet.com>
> To: <comets-ml at yahoogroups.com>; <asvcometsection at yahoogroups.com>; "BAA
> Comets discussion list" <comets-disc at britastro.org>
> Sent: Tuesday, February 03, 2015 11:53 PM
> Subject: [BAA Comets] First outburst of Comet 29P in 2015
>
>> Three images I scheduled taken of Comet 29P/Schwassmann-Wachmann earlier
>> today (February 03.76) using the LCOGT network at Siding Spring appear to
>> show that this comet is now in outburst.
>>
>> I have temporarily posted an image depicting the possible outburst,
>> alongside one from the ESO Digital Sky Survey for the same area of sky,
>> here:
>> http://britastro.org/asteroids/29P_2015Feb3_outburst.png
>>
>> Jean-Francois Soulier has been monitoring 29P during the start of this
>> new
>> apparition beginning on January 11. His results indicate that the comet
>> has not outburst between the start of 2015 and the time of his most
>> recent
>> frame taken from SpaceObs, San Pedro de Atacama, Chile, namely 2015
>> February 02.39 when the comet was roughly magnitude 17-18.
>>
>> The last observed outburst of 29P took place on 2014 October 20. Grateful
>> if observers can confirm this possible outburst. Those located in the
>> southern hemisphere will be best placed given that the comet is now at
>> Declination -30 degrees. Its elongation is only 51 degrees visible in the
>> pre-dawn sky. The image referred to above is taken from a preview jpeg
>> and
>> so it is difficult to judge the brightness of this possible outburst. My
>> estimate is brighter than R=15. How much brighter I cannot yet determine.
>>
>> Clear Skies,
>>
>> Richard Miles
>> BAA
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