Discovery of fragment of comet C/2015 ER61 (PANSTARRS)
In collaboration with F.-J. (Josch) Hambsch, we noticed since a couple of days a change in the shape of the central condensation of comet C/2015 ER61 (PANSTARRS), so we carefully observed the next following days the shape of the central condensation. On 13 june 2017 we could determine clearly a second condensation on a small distance of the central condensation and inside the tail. The following days we could confirm this and the second condensation was very slow on more distance from the central condensation of the comet. This was clearly a fragment of this comet !. Until now there was no reporting of this known of this fragmentation. So I made this report of 3 observation days and send it to CBAT and MPC (Minor planetcenter) We are looking for someone for confirmation and A. Maury of SpaceObs in Chile could make this confirmation for us and send it to the CBAT and MPC as well. Meanwhile there was an unindependant observation on 17 june 2017 by Gian-Luca Masi from TENAGRA II.
This comet (cf. CBETs 4249, 4383) has evidently experienced a splitting:
a companion fragment (denoted 'B') was reported by E. Bryssinck (Kruibeke, Belgium) from CCD images taken by F.-J.Hambsch (Mol, Belgium) and himself on June 13, 15, and 16 remotely with a 0.4-m f/6.8 reflector (both unfiltered and with a Bessel R filter) at the private "ROAD Observatory" located at San Pedro de Atacama, Chile; Bryssinck noticed a change over a couple of days in the shape of the nuclear condensation, followed by the appearance of a possible nuclear fragment inside the coma and tail. On June 13.41 UT, seven exposures show a very faint fragment located 12".3 from the main nuclear condensation in p.a. 243 degrees with a diameter of 8" (magnitude R = 16.5 in an aperture of diameter 5".4). Seven images taken on June 15.42 show the very faint fragment 13".0 from the main condensation in the same direction and with magnitude R = 16.6 in the same-sized aperture. Nine images taken on June 16.41 show component B at size 8".8 (with R = 16.6 in a 5".4 aperture) and located 13".4 from component A in p.a. 248 deg. Component B is difficult to see due its small distance from component A and to its location within the tail.
G. Masi (Ceccano, Italy) and M. Schwartz (Rio Rico, AZ, USA) imaged comet C/2015 ER_61 around June 17.446 …. Snip….
