https://groups.yahoo.com/neo/groups/comets-ml/conversations/messages/27172Hello all,
Not only is comet C/2017 S3 (PANSTARRS) fading (last night, the central condensation was about 1.5 magnitudes fainter than three nights ago), but the orbit apparently changed as well. My orbit calculations (using Find_Orb) are based on the data published by the MPC (last observation was May 21) and my own observations in the last two months. It was quite easy to find an orbit for all data up to July 20 (mean residual of 0.46“). However, that orbit turned out to be inconsistent with my astrometric results obtained since July 21. The problem is document in the table provided below.
My G40 observations from last night (July 23) can be made consistent with the observations until July 20 by subtracting 52 seconds from the true observation time. In other words, the comet appears to be delayed by 52 seconds now. For my H06 observations on July 21 the delay is about 30 seconds. The apparent delay could be a sign of disintegration.
Kind regards
Bernd Lütkenhöner
Table: My observations of the last 10 days. The residuals (in arcsecs) are given in the last two columns.
18 07 14.20524 G40 04 21 33.26 +57 36 15.1 .62- .45+
18 07 14.21234 G40 04 21 36.34 +57 36 06.8 .41- .01-
18 07 14.21538 G40 04 21 37.70 +57 36 03.5 .01+ .06+
18 07 16.19733 G40 04 36 15.65 +56 53 26.9 .36+ .39-
18 07 16.20594 G40 04 36 19.56 +56 53 15.0 .40+ .09-
18 07 16.20943 G40 04 36 21.15 +56 53 10.0 .46+ .14-
18 07 17.19361 G40 04 43 54.20 +56 27 53.4 .47+ .13+
18 07 17.20059 G40 04 43 57.43 +56 27 41.9 .32+ .22-
18 07 17.20405 G40 04 43 58.99 +56 27 36.8 .10- .21+
18 07 18.20407 G40 04 51 51.01 +55 58 44.2 .05- .13-
18 07 18.21806 G40 04 51 57.71 +55 58 19.2 .20+ .06+
18 07 20.44847 H06 05 10 12.39 +54 40 37.5 .05+ .02-
18 07 20.45396 H06 05 10 15.14 +54 40 24.9 .04- .15+
18 07 21.44265 X H06 05 18 38.26 +53 59 18.0 1.6- .86+
18 07 21.45007 X H06 05 18 42.09 +53 58 59.1 1.5- 1.2+
18 07 22.20753 X G40 05 25 14.86 +53 24 20.6 2.7- 2.2+
18 07 22.21098 X G40 05 25 16.62 +53 24 10.6 3.0- 2.0+
18 07 22.21444 X G40 05 25 18.47 +53 24 00.9 2.6- 2.0+
18 07 23.20189 X G40 05 33 59.72 +52 34 19.8 3.2- 2.4+
18 07 23.20859 X G40 05 34 03.28 +52 33 58.4 3.3- 2.0+
18 07 23.21207 X G40 05 34 05.25 +52 33 47.5 2.3- 2.1+
18 07 23.21902 X G40 05 34 08.91 +52 33 26.0 2.6- 2.4+
18 07 23.22244 X G40 05 34 10.76 +52 33 14.7 2.4- 1.9+
觀星論壇 
