[BAA Comets] 29P Brightening?

Richard Miles rmiles.btee at btinternet.com
Fri Jul 28 22:13:43 BST 2017


Well done Peter, Erik and Dr Clay for spotting the recent low-level activity at 29P.

As you know Jean-François and I (via Las Cumbres Obs) have been keeping a close watch on this most unusual 'weird' comet.
In fact, there have been 2 outbursts very recently, each of about 0.3 mag separated in time by a little over 2 days on July 25 and July 27

The outbursts were as follows:

In 5.7" radius aperture:
2017 July 25.50 +/-0.05 from 16.29R to 16.02R, Amplitude=0.27mag (0.35 mag in 1.8" radius aperture, 2.0-m scope)
2017 July 27.72 +/-0.05 from 16.00R to 15.63R, Amplitude=0.37mag (0.46 mag in 1.8" radius aperture, 2.0-m scope)

Dr Clay's result corresponded to 'after the 1st event' but 'before the 2nd one'.

Erik and Peter's were after the 2nd one (there is a -0.3 mag correction needed to be applied to Peter's data).

The first of these 2 outbursts holds the record for the faintest such event ever detected at 29P. The 2nd is not far behind either. A few years ago such events would have gone largely unnoticed, so it is a credit to observers efforts that these are now being picked up.

The comet has now just completed 2 orbits of the Sun since Dave Jewitt reported observations of 29P from 1987 June when photometric monitoring of the comet appeared to show it exhibiting an underlying  continuous activity resulting in a persistent coma, as well as the occasional large outburst. See:
http://adsabs.harvard.edu/full/1990ApJ...351..277J

In those days the cadence of the photometric observations as well as their precision wasn't able to show the true picture as to what really was happening. In fact, the last 5 weeks of observations have been especially successful in all sorts of ways, including detecting 6 outbursts, time-series from 2 observers following the development of a strong outburst from quiescence ( https://www.britastro.org/node/10684 ), spotting pairs of outbursts separated by 2.2 and 2.5 days, and picking up very faint outbursts in the last couple of days.

So in fact, what appears to be persistent activity is almost all a result of small step-changes in brightness of the nucleus, which create the illusion of continuous activity. Indeed, the ability of one outburst to trigger follow-on events is especially remarkable.

It is encouraging to note that 29P is moving north in declination, approaching perihelion, and will be very well placed for observation in the next few years. 

Clear skies.

Richard Miles
BAA

P.S.  I've pasted recent photometry at the foot of this note

  ----- Original Message ----- 
  From: P. Clay Sherrod 
  To: BAA comet group ; Peter Carson 
  Cc: Richard Miles Alt ; Richard Miles 
  Sent: Friday, July 28, 2017 3:19 PM
  Subject: Re: 29P Brightening?


  Here are our results from July 27; using three different programs (Astrometrica, CCDsoft and CCDops) our magnitudes all came out consistent, but the results always seem to be questioned so there was no reason to really post them.  They show a 0.4 mag. brightening from the week prior.
  ----
  COD H45
  CON [drclay at tcworks.net]
  OBS P.C. Sherrod
  MEA P.C. Sherrod
  ACK ASO Observations
  AC2 drclay at tcworks.net
  TEL 0.51-m f/5.6 astrograph + CCD
  COM k2000, 7.4 pixel binned 2x2
  COM Charon version Oct 27 2014 09:27:49
  COM Report file created Thu Jul 27 02:10:57 2017
  NET UCAC4
  Radius aperture = 11"
  0029P         C2017 07 27.35239 21 29 58.70 -13 41 31.9          15.8 N      H45
  0029P         C2017 07 27.35450 21 29 58.65 -13 41 32.0          15.9 N      H45
  0029P         C2017 07 27.35698 21 29 58.58 -13 41 32.2          15.9 N      H45
  0029P         C2017 07 27.35864 21 29 58.53 -13 41 32.4          15.9 N      H45
  0029P         C2017 07 27.36014 21 29 58.49 -13 41 32.5          15.8 N      H45


    ----- Original Message ----- 
    From: Peter Carson 
    To: BAA comet group 
    Sent: Friday, July 28, 2017 8:15 AM
    Subject: 29P Brightening?


    Hi All,
    Anyone seeing 29P brightening?
    I imaged 29P this morning (28th Jul) and measured its mag at 15.9 using a 6.7” rad aperture and it appears to have brightened by 0.7 mag. My last image and measure was on July 21st when it was mag 16.6 measured in the same way.
    Both images are attached.
    Peter 

    --------------------------------------------------------------------------------------
    Observation logs:

    Las Cumbres Observatory:
    0029P         C2017 07 24.62619 21 31 10.07 -13 38 16.8          16.31N      Q58
    0029P         C2017 07 24.62839 21 31 10.02 -13 38 17.0          16.27N      Q58
    0029P         C2017 07 24.63057 21 31 09.96 -13 38 17.1          16.28N      Q58

    0029P         C2017 07 24.72324 21 31 07.51 -13 38 23.5          16.31N      E10
    0029P         C2017 07 24.72481 21 31 07.46 -13 38 23.4          16.28N      E10
    0029P         C2017 07 24.72640 21 31 07.43 -13 38 23.6          16.30N      E10
    0029P         C2017 07 24.72797 21 31 07.38 -13 38 23.6          16.30N      E10
    0029P         C2017 07 24.72954 21 31 07.34 -13 38 23.6          16.29N      E10

    0029P         C2017 07 24.80445 21 31 05.38 -13 38 28.9          16.18N      Q58
    0029P         C2017 07 24.80667 21 31 05.31 -13 38 29.1          16.19N      Q58
    0029P         C2017 07 24.80888 21 31 05.26 -13 38 29.2          16.16N      Q58

    0029P         C2017 07 25.56342 21 30 45.84 -13 39 21.8          16.13N      E10 rise to outburst
    0029P         C2017 07 25.56498 21 30 45.79 -13 39 22.1          16.09N      E10
    0029P         C2017 07 25.56655 21 30 45.74 -13 39 22.2          16.11N      E10
    0029P         C2017 07 25.56812 21 30 45.71 -13 39 22.1          16.16N      E10
    0029P         C2017 07 25.56972 21 30 45.66 -13 39 22.4          16.09N      E10

    0029P         C2017 07 25.62968 21 30 44.06 -13 39 26.7          15.97N      Q59 outburst!
    0029P         C2017 07 25.63190 21 30 44.01 -13 39 26.8          16.00N      Q59
    0029P         C2017 07 25.63413 21 30 43.95 -13 39 27.0          16.02N      Q59

    0029P         C2017 07 25.74885 21 30 40.89 -13 39 34.8          16.04N      E10
    0029P         C2017 07 25.75042 21 30 40.84 -13 39 35.0          16.03N      E10
    0029P         C2017 07 25.75199 21 30 40.80 -13 39 35.2          16.02N      E10
    0029P         C2017 07 25.75355 21 30 40.76 -13 39 35.3          16.04N      E10
    0029P         C2017 07 25.75512 21 30 40.71 -13 39 35.3          16.04N      E10

    0029P         C2017 07 25.80463 21 30 39.39 -13 39 40.1          16.00N      Q58
    0029P         C2017 07 25.80684 21 30 39.36 -13 39 40.7          16.00N      Q58
    0029P         C2017 07 25.80905 21 30 39.29 -13 39 39.5          16.02N      Q58

    0029P         C2017 07 26.43968 21 30 22.89 -13 40 25.4          16.10N      F65
    0029P         C2017 07 26.44125 21 30 22.84 -13 40 25.5          16.09N      F65
    0029P         C2017 07 26.44282 21 30 22.80 -13 40 25.6          16.07N      F65
    0029P         C2017 07 26.44438 21 30 22.76 -13 40 25.7          16.07N      F65
    0029P         C2017 07 26.44595 21 30 22.70 -13 40 25.5          16.09N      F65

    0029P         C2017 07 26.62986 21 30 17.85 -13 40 37.6          16.02N      Q58
    0029P         C2017 07 26.63208 21 30 17.79 -13 40 37.7          16.02N      Q58
    0029P         C2017 07 26.63429 21 30 17.73 -13 40 37.9          16.03N      Q58

    0029P         C2017 07 27.06518 21 30 06.39 -13 41 10.6          15.91N      Z21
    0029P         C2017 07 27.06735 21 30 06.31 -13 41 10.9          15.96N      Z21
    0029P         C2017 07 27.06954 21 30 06.26 -13 41 10.6          15.99N      Z21

    0029P         C2017 07 27.56343 21 29 53.19 -13 41 44.7          16.02N      E10
    0029P         C2017 07 27.56504 21 29 53.12 -13 41 44.9          16.03N      E10
    0029P         C2017 07 27.56661 21 29 53.10 -13 41 45.1          16.00N      E10
    0029P         C2017 07 27.56818 21 29 53.06 -13 41 45.1          16.01N      E10
    0029P         C2017 07 27.56975 21 29 53.02 -13 41 45.3          16.04N      E10

    0029P         C2017 07 27.61551 21 29 51.77 -13 41 48.7          15.96N      Q58
    0029P         C2017 07 27.61770 21 29 51.71 -13 41 48.9          15.97N      Q58
    0029P         C2017 07 27.61770 21 29 51.71 -13 41 48.9          15.97N      Q58

    0029P         C2017 07 27.80444 21 29 46.63 -13 42 02.6          15.67N      Q58 outburst!
    0029P         C2017 07 27.80663 21 29 46.58 -13 42 02.4          15.68N      Q58
    0029P         C2017 07 27.80882 21 29 46.51 -13 42 02.8          15.69N      Q58

    0029P         C2017 07 28.50128 21 29 28.19 -13 42 53.6          15.65N      E10
    0029P         C2017 07 28.50284 21 29 28.13 -13 42 53.9          15.62N      E10
    0029P         C2017 07 28.50443 21 29 28.10 -13 42 53.9          15.67N      E10
    0029P         C2017 07 28.50599 21 29 28.05 -13 42 54.1          15.65N      E10
    0029P         C2017 07 28.50756 21 29 28.01 -13 42 54.2          15.65N      E10

    0029P         C2017 07 28.62624 21 29 24.75 -13 43 03.1          15.65N      Q58
    0029P         C2017 07 28.62846 21 29 24.69 -13 43 03.1          15.66N      Q58
    0029P         C2017 07 28.63065 21 29 24.63 -13 43 03.2          15.63N      Q58

    0029P         C2017 07 28.76558 21 29 20.92 -13 43 12.9          15.59N      E10
    0029P         C2017 07 28.76715 21 29 20.90 -13 43 13.2          15.61N      E10
    0029P         C2017 07 28.76872 21 29 20.83 -13 43 13.2          15.61N      E10
    0029P         C2017 07 28.77028 21 29 20.79 -13 43 13.6          15.58N      E10
    0029P         C2017 07 28.77185 21 29 20.77 -13 43 13.5          15.61N      E10

    Jean-François Soulier:
    0029P         C2017 07 24.12202 21 31 23.10 -13 37 42.7          16.53N      W96 
    0029P         C2017 07 24.15890 21 31 22.12 -13 37 45.2          16.47N      W96
    0029P         C2017 07 24.19653 21 31 21.14 -13 37 47.8          16.44N      W96

    0029P        KC2017 07 24.97113 21 31 01.22 -13 38 43.5          16.30N      A77
    0029P        KC2017 07 25.00075 21 31 00.44 -13 38 45.3          16.40N      A77
    0029P        KC2017 07 25.07253 21 30 58.54 -13 38 50.5          16.42N      A77
    0029P        KC2017 07 25.12735 21 30 57.11 -13 38 54.2          16.50N      A77

    0029P         C2017 07 25.19688 21 30 55.36 -13 38 57.0          16.48N      W96
    0029P         C2017 07 25.22999 21 30 54.48 -13 38 59.2          16.39N      W96
    0029P         C2017 07 25.26385 21 30 53.60 -13 39 01.7          16.46N      W96

    0029P         C2017 07 25.96576 21 30 35.31 -13 39 52.5          16.14N      C10 outburst!
    0029P         C2017 07 26.01403 21 30 34.04 -13 39 56.2          16.20N      C10
    0029P         C2017 07 26.06370 21 30 32.67 -13 39 59.5          16.16N      C10

    0029P         C2017 07 26.12041 21 30 31.33 -13 40 01.7          16.24N      W96
    0029P         C2017 07 26.15443 21 30 30.42 -13 40 04.0          16.11N      W96
    0029P         C2017 07 26.18830 21 30 29.49 -13 40 06.8          16.21N      W96

    0029P        KC2017 07 26.98181 21 30 08.59 -13 41 05.1          16.15N      A77
    0029P        KC2017 07 27.02155 21 30 07.53 -13 41 07.9          16.17N      A77
    0029P        KC2017 07 27.04678 21 30 06.85 -13 41 10.3          16.19N      A77
    0029P        KC2017 07 27.08356 21 30 05.87 -13 41 13.0          16.26N      A77

    0029P         C2017 07 27.13347 21 30 04.61 -13 41 14.2          16.11N      W96
    0029P         C2017 07 27.16295 21 30 03.82 -13 41 16.6          16.08N      W96
    0029P         C2017 07 27.19346 21 30 02.98 -13 41 18.6          16.13N      W96
    0029P         C2017 07 27.22396 21 30 02.17 -13 41 20.8          16.15N      W96
    0029P         C2017 07 27.25434 21 30 01.34 -13 41 23.2          16.10N      W96

    0029P         C2017 07 27.96824 21 29 42.39 -13 42 16.8          15.85N      A77 outburst!
    0029P         C2017 07 28.01228 21 29 41.20 -13 42 20.3          15.77N      A77
    0029P         C2017 07 28.05631 21 29 40.00 -13 42 23.1          15.79N      A77
    0029P         C2017 07 28.10106 21 29 38.76 -13 42 26.3          15.71N      A77
    0029P         C2017 07 28.12490 21 29 38.12 -13 42 28.4          15.63N      A77

    0029P         C2017 07 28.12682 21 29 38.20 -13 42 26.5          15.67N      W96
    0029P         C2017 07 28.14490 21 29 37.69 -13 42 27.7          15.70N      W96
    0029P         C2017 07 28.16370 21 29 37.19 -13 42 29.2          15.81N      W96



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