[Iaude] CBET 4832: COMET P/2008 QP20

quai at eps.harvard.edu quai at eps.harvard.edu
Sun Aug 16 20:04:56 EDT 2020


                                                  Electronic Telegram No. 4832
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


RECOVERY OF COMET P/2008 QP_20 (LINEAR-HILL)
     S. Nakano, Central Bureau, has identified recovery observations of comet
P/2008 QP_20 (cf. IAUC 8979) in astrometry published on MPEC 2020-P19; the
astrometry, which is tabulated below, was reported by S. Deen, Simi Valley,
CA, USA, from DECam images obtained with the 4.0-m reflector at Cerro Tololo.
Following a query by the Central Bureau, Deen provides additional information:
he measures a small slightly condensed coma of size about 2" (full-width-at-
half-maximum) on the g-band (first) image from 2016 Jan. 15.26 UT, with the
seeing 1".4, and notes a possible very faint, diffuse tail 15" long toward
p.a. 260 degrees; the second (r-band) image on Jan. 15 shows a moderately
condensed coma of size 1".5 (FWHM) in 1".3 seeing, noting also a faint,
broad 15" tail in p.a. 260 degrees.  On the z-band images from 2016 Mar.
1.14, taken in 1".1 seeing, Deen sees the comet as very close to the stellar
size with no visible tail.

     2016 UT             R.A. (2000) Decl.       Mag.
     Jan. 15.25925    9 32 52.77   +17 38 30.6   21.4
          15.26029    9 32 52.74   +17 38 31.0   21.6
     Mar.  1.13752    8 50 41.89   +18 41 57.4
           1.13891    8 50 41.82   +18 41 57.4   21.8

The residuals of the recovery observations above were -29" in R.A. and +17"
in Decl. with respect to the prediction in the ICQ's 2014 Comet Handbook (and
NK 2300), with the indicated correction to the time of perihelion being
Delta(T) = +0.03 day.  The following linked orbital elements by Nakano are
from 477 observations spanning 2008 Aug. 25-2016 Mar. 1 (mean residual 0".6).

                    Epoch = 2008 Oct. 21.0 TT
     T = 2008 Nov.  2.69871 TT        Peri. =  72.03934
     e = 0.5063110                    Node  = 325.15191 2000.0
     q = 1.7231412 AU                 Incl. =   7.74979
       a =  3.4903371 AU   n = 0.15114821   P =   6.52 years

                    Epoch = 2015 May  18.0 TT
     T = 2015 May  17.27592 TT        Peri. =  72.35404
     e = 0.5063876                    Node  = 324.96675 2000.0
     q = 1.7233825 AU                 Incl. =   7.74179
       a =  3.4913677 AU   n = 0.15108129   P =   6.52 years

                    Epoch = 2022 Jan. 21.0 TT
     T = 2022 Jan.  2.13736 TT        Peri. =  75.54133
     e = 0.4913052                    Node  = 322.07073 2000.0
     q = 1.8062430 AU                 Incl. =   7.52187
       a =  3.5507401 AU   n = 0.14730780   P =   6.69 years

                    Epoch = 2028 Sept.26.0 TT
     T = 2028 Sept.16.96896 TT        Peri. =  75.68914
     e = 0.4900286                    Node  = 321.98807 2000.0
     q = 1.8148516 AU                 Incl. =   7.51303
       a =  3.5587319 AU   n = 0.14681187   P =   6.71 years

                    Epoch = 2035 June  2.0 TT
     T = 2035 June  1.23314 TT        Peri. =  75.59879
     e = 0.4901628                    Node  = 321.95452 2000.0
     q = 1.8148645 AU                 Incl. =   7.50859
       a =  3.5596943 AU   n = 0.14675234   P =   6.72 years

The following ephemeris by the undersigned for the next return of this comet,
from the above elements, uses photometric power-law parameters H = 14.0 and
2.5n = 15 for the pre-perihelion magnitudes, based entirely on the 2008
pre-perihelion astrometric magnitudes.  There appears to be an asymmetry
between pre-perihelion and post-perihelion brightness, with H = 14.0 and
2.5n = 10 better representing the 2008-2009 post-perihelion reported
magnitudes, and these parameters are used below for post-perihelion
predicted magnitudes; however, the 2016 data reported by Deen (above) are
two magnitudes fainter than these parameters suggest.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2021 07 05    23 09.00   -05 08.6    1.733    2.370   116.6    22.5  20.8
2021 07 15    23 13.53   -04 02.0    1.587    2.321   124.7    21.1  20.5
2021 07 25    23 15.81   -03 02.8    1.453    2.273   133.3    19.0  20.2
2021 08 04    23 15.56   -02 12.6    1.333    2.226   142.6    16.1  19.8
2021 08 14    23 12.61   -01 32.7    1.231    2.180   152.5    12.4  19.5
2021 08 24    23 07.11   -01 03.9    1.149    2.135   162.8     8.0  19.2
2021 09 03    22 59.61   -00 45.5    1.088    2.093   172.5     3.6  19.0
2021 09 13    22 51.12   -00 35.7    1.052    2.052   171.2     4.3  18.8
2021 09 23    22 43.04   -00 30.1    1.038    2.013   160.9     9.4  18.6
2021 10 03    22 36.75   -00 23.9    1.046    1.977   150.0    14.7  18.5
2021 10 13    22 33.38   -00 12.0    1.073    1.944   139.6    19.4  18.5
2021 10 23    22 33.56   +00 10.1    1.115    1.914   130.0    23.5  18.5
2021 11 02    22 37.43   +00 44.9    1.169    1.886   121.3    26.7  18.5
2021 11 12    22 44.84   +01 33.9    1.233    1.863   113.4    29.2  18.5
2021 11 22    22 55.42   +02 37.5    1.303    1.843   106.4    30.9  18.6
2021 12 02    23 08.74   +03 55.0    1.378    1.828    99.9    32.1  18.6
2021 12 12    23 24.40   +05 25.2    1.458    1.816    94.1    32.7  18.7
2021 12 22    23 42.01   +07 06.4    1.541    1.809    88.7    32.9  18.8
2022 01 01    00 01.25   +08 56.2    1.627    1.806    83.7    32.8  18.9

2022 01 11    00 21.87   +10 52.3    1.716    1.808    79.0    32.3  17.7
2022 01 21    00 43.64   +12 51.9    1.807    1.814    74.6    31.5  17.9
2022 01 31    01 06.39   +14 52.1    1.902    1.825    70.4    30.6  18.0
2022 02 10    01 29.97   +16 50.2    1.999    1.839    66.3    29.4  18.2
2022 02 20    01 54.24   +18 43.5    2.098    1.858    62.3    28.1  18.3
2022 03 02    02 19.09   +20 29.4    2.200    1.881    58.4    26.7  18.5
2022 03 12    02 44.41   +22 05.8    2.303    1.907    54.5    25.1  18.6
2022 03 22    03 10.05   +23 30.7    2.408    1.937    50.7    23.5  18.8
2022 04 01    03 35.89   +24 42.8    2.513    1.969    46.8    21.7  18.9
2022 04 11    04 01.81   +25 40.9    2.618    2.005    42.9    19.9  19.1


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2020 CBAT
2020 August 16                   (CBET 4832)              Daniel W. E. Green



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