[BAA Comets] Very rare outburst of Comet 174P/Echeclus / Asteroid (60558) Echeclus

[Richard Miles]

Comet 174P has within the last 24 hours undergone a strong (2.6 mag) 
outburst as detected by Paul Camilleri observing from Blue Mountains 
Observatory, Leura, NSW, Australia (MPC Q68). Time of outburst appears to 
have been 2016 August 28.2 +/-0.4. Paul has asked me to alert observers.

Here are the results of my photometric measurements of some of Paul 
Camilleri's images:

COD Q68
COM Filter: Clear
COM Photometric aperture: 5.2" radius
OBS P. Camilleri
MEA R. Miles
TEL 0.30-m f/5.4 Schmidt-Cassegrain + CCD
ACK MPCReport file updated 2016.08.28 22:20:00
NET UCAC-4
0174P         C2016 08 27.71786 01 27 15.82 +07 07 18.5          17.76N 
Q68
0174P         C2016 08 27.74484 01 27 15.60 +07 07 16.1          17.92N 
Q68
0174P         C2016 08 28.68603 01 27 07.86 +07 05 55.1          15.21N 
Q68
0174P         C2016 08 28.70610 01 27 07.68 +07 05 53.3          15.23N 
Q68
----- end -----

Here is confirmation of the outburst using one of the 1.0-m LCOGT telescopes 
at Sutherland, South Africa:

COD K92
COM Filter: SDSS-r'
COM Photometric aperture: 5.6" radius
OBS R. Miles, LCOGT
MEA R. Miles
TEL 1.0-m f/8.0 Ritchey-Chretien + CCD
ACK MPCReport file updated 2016.08.28 23:56:45
AC2 rmiles at baa.u-net.com
NET UCAC-4
0174P         C2016 08 28.98523 01 27 05.32 +07 05 28.8          15.27N 
K92
0174P         C2016 08 28.98742 01 27 05.30 +07 05 28.8          15.27N 
K92
0174P         C2016 08 28.98960 01 27 05.28 +07 05 28.6          15.29N 
K92
----- end -----

Further confirmation from LCOGT, Tenerife. Single measurement - other images 
affected by mist.

COD Z21
COM Filter: SDSS-r'
COM Photometric aperture: 5.7" radius
OBS R. Miles, LCOGT
MEA R. Miles
TEL 0.40-m f/8 Schmidt-Cassegrain + CCD
ACK MPCReport file updated 2016.08.29 00:16:16
NET UCAC-4
0174P         C2016 08 28.98311 01 27 05.38 +07 05 27.6          15.25N 
Z21
----- end -----

Jean-François Soulier has also provided accurate astrometry/photometry as 
follows:

COD C10
COM Filter: Clear
COM Photometric aperture: 6.5" radius
CON JEAN-FRANCOIS SOULIER [jean-francois.soulier2 at wanadoo.fr]
OBS J.-F. Soulier
MEA J.-F. Soulier
TEL 0.30-m f/3.8 Newtonian reflector + CCD
ACK MPCReport file updated 2016.08.28
AC2 jean-francois.soulier2 at wanadoo.fr
NET UCAC-4
0174P         C2016 08 28.94562 01 27 05.67 +07 05 30.3          15.44N 
C10
0174P         C2016 08 28.96921 01 27 05.47 +07 05 28.3          15.37N 
C10
0174P         C2016 08 28.99322 01 27 05.26 +07 05 26.2          15.33N 
C10
----- end -----

This object appears to have undergone two outbursts since its discovery in 
2000 by Steward Observatory (Spacewatch) as a then asteroidal object. That 
of 2005 December / 2006 January was slighly brighter than this one and was 
associated with the appearance of a disintegrating chunk of material, which 
was well observed with large telescopes. The object was subsequently 
assigned a number as a periodic comet. A second outburst of 2011 May was 
considerably fainter than the present event. It is currently 16 months after 
perihelion (q = 5.82 AU,Q = 15.54 AU, Period = 34.9 yr).

Observers are strongly urged to monitor the development of this most rare 
outburst.

Richard Miles
British Astronomical Association