Guoyou Sun's Home Page

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My Comet Discoveries

 

the 2015 Edgar Wilson Award

 

First Discovery

C/2015 F5 (SWAN-Xingming)

Epoch 2015 June 27.0 TT = JDT 2457200.5
T 2015 Mar. 28.1003 TT                                                                      MPC
q   0.346018             (2000.0)                       P                   Q
n   0.0160525      Peri.   13.3968       +0.1067626      -0.8669107             T = 2457109.60032 JDT
a  15.563488       Node   287.7411    -0.9528567      -0.2290884              q =     0.3460175
e   0.977767        Incl.  149.2557       -0.2840173      +0.4427013             Earth MOID = 0.44137 AU
P  61.4

 

CBAT 4091

Electronic Telegram No. 4091


Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge,MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2015 F5 (SWAN-XINGMING)
     Several people noticed a moving object on low-resolution public website
hydrogen Lyman-alpha images obtained during Mar. 29-Apr. 1 with the Solar Wind
Anisotropies (SWAN) camera on the Solar and Heliospheric Observer (SOHO)
spacecraft (see CBET 4068 and website URL http://swan.projet.latmos.ipsl.fr/)£¬
and the Central Bureau received two such reports during mid-day (UT) on Apr. 4
from Szymon Liwo (Swidnica,Poland) and from Worachate Boonplod (Samut
Songkhram,Thailand),both of whom provided approximate positions.  M.
Mattiazzo,Swan Hill,Victoria,Australia,reports the following approximate
positions for the object (uncertainty up to a degree,with an uncertain
assumption of 12h UT for each image).

     2015 UT         R.A. (2000) Decl.
     Mar. 29.5     23 04.1      -00 53
          30.5     23 06.4      +00 52
          31.5     23 09.3      +02 56
     Apr.  1.5     23 13.2      +04 58

For comparison,R. Matson (Newport Coast,CA, USA) provides his measurements
from the same images:

     2015 UT         R.A. (2000) Decl.
     Mar. 29.5     23 06.1      -01 30
          30.5     23 07.4      +01 05
          31.5     23 09.6      +03 20
     Apr.  1.5     23 13.5      +04 55

Early on Apr. 5 UT (apparently before any public posting of a possible new
comet on SWAN images was made),a report was received from Xing Gao (XinJiang£¬
China) of the independent discovery of an unknown comet with a 30" coma by
Guoyou Sun on images taken in twilight on Apr. 4.9 UT (discovery observations
tabulated below) by Gao with a 0.11-m f/5 refractor in the course of the
Xingming sky survey; they imaged about 32 square degrees of neighboring area
around the comet that morning.  Sun then checked online SWAN images and
noticed the above-mentioned four images moving with a motion and location
consistent with the Xingming images.

     2015 UT             R.A. (2000) Decl.       Mag.   Observer
     Apr.  4.93769   23 27 58.07   +11 48 08.5   12.7   Gao
           4.94028   23 27 58.29   +11 48 32.3   12.2    "
           4.94288   23 27 59.40   +11 48 46.9   11.2    "

Additional images obtained by Gao with the 0.11-m refractor (and measured by
M.-T. Hui and G. Sun) show a coma diameter around 50" on Apr. 5.9 and around
1'.0 on Apr. 6.9 (with magnitude V = 11.4-11.7); follow-up images on Apr. 7.9
show a 1'.2 coma of red mag 11.4-12.5 with a 4'.5 tail in p.a. 300 deg.  After
the object was posted on the Minor Planet Center's PCCP webpage,other
observations have also shown cometary appearance.  Hui also reports that CCD
images taken by Z.-Q. Guo with another 0.11-m refractor in China on Apr. 5.8
show a cyan color to the coma,whose diameter was around 50" with magnitude
11.3 and no tail in twilight.  L. Buzzi (Varese, Italy,0.60-m f/4.64
reflector) writes that stacked images taken in twilight and at low altitude
(11 deg) on Apr. 8.15-8.16 show a 2' coma of red mag 14.0 without a strong
central condensation and a thin,straight tail at least 6'.5 long in p.a.
307 deg; thirty stacked 10-s images taken in slightly better conditions at
10 deg altitude by Buzzi on Apr. 9.15 reveal a round coma 3' wide and a tail
at least 6' long in p.a. 300 deg (after the first 4',the tail widens).
     Visual total-magnitude and coma-diameter estimates:  Apr. 8.19 UT,8.2£¬
1'.7 (J. J. Gonzalez,Leon,Spain; 20.3-cm reflector at Villaverde de
Arcayos; altitude 8 degrees in twilight; condensed coma); 10.10,7.9,5' (M.
Reszelski,Szamotuly-Galowo,Poland,15x70 binoculars); 10.48,9.6:,2' (A.
Hale,Cloudcroft,NM,0.41-m reflector; low altitude; bright moonlight£¬
twilight).
     The available ground-based astrometry,the following very preliminary
parabolic orbital elements by G. V. Williams (from the poor-quality ground-
based astrometry alone,spanning Apr. 4-10),and an ephemeris appear on
MPEC 2015-G27.

     T = 2015 Mar. 28.4308 TT         Peri. =  15.3704
                                      Node  = 288.5830  2000.0
     q = 0.347798 AU                  Incl. = 148.8845


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

                         (C) Copyright 2015 CBAT
2015 April 10                    (CBET 4091)              Daniel W. E. Green

MPEC 2015-G27

M.P.E.C. 2015-G27                                Issued 2015 Apr. 10,19:03 UT

     The Minor Planet Electronic Circulars contain information on unusual
         minor planets and routine data on comets.  They are published
   on behalf of Commission 20 of the International Astronomical Union by the
          Minor Planet Center,Smithsonian Astrophysical Observatory£¬
                          Cambridge,MA 02138,U.S.A.

             Prepared using the Tamkin Foundation Computer Network

                              MPC@CFA.HARVARD.EDU
            URL http://www.minorplanetcenter.net/    ISSN 1523-6714

                        COMET C/2015 F5 (SWAN-XINGMING)

Observations:
    CK15F050  C2015 04 04.93769 23 27 58.07 +11 48 08.5          12.7 TdEG027C42
    CK15F050  C2015 04 04.94028 23 27 58.29 +11 48 32.3          12.2 TdEG027C42
    CK15F050  C2015 04 04.94288 23 27 59.40 +11 48 46.9          11.2 TdEG027C42
    CK15F050  V2015 04 05.83410 23 33 01.67 +14 08 34.3                 EG027247
    CK15F050  v2015 04 05.83410 1 123.7460   +41.5985     230           EG027247
    CK15F050  V2015 04 05.84251 23 33 04.52 +14 09 53.3                 EG027247
    CK15F050  v2015 04 05.84251 1 123.7460   +41.5985     230           EG027247
    CK15F050  V2015 04 05.84737 23 33 06.52 +14 10 38.3          11.3 T EG027247
    CK15F050  v2015 04 05.84737 1 123.7460   +41.5985     230           EG027247
    CK15F050  V2015 04 05.85087 23 33 07.90 +14 11 14.3                 EG027247
    CK15F050  v2015 04 05.85087 1 123.7460   +41.5985     230           EG027247
    CK15F050  V2015 04 05.85537 23 33 09.02 +14 11 55.4                 EG027247
    CK15F050  v2015 04 05.85537 1 123.7460   +41.5985     230           EG027247
    CK15F050  C2015 04 05.94317 23 33 41.76 +14 26 15.0                 EG027C42
    CK15F050  C2015 04 05.94595 23 33 43.25 +14 26 45.1          11.9 T EG027C42
    CK15F050  C2015 04 05.94873 23 33 44.20 +14 27 07.6          11.8 T EG027C42
    CK15F050  C2015 04 06.93601 23 40 25.33 +17 12 49.1          11.1 T EG027C42
    CK15F050  C2015 04 06.93721 23 40 26.00 +17 12 59.5          11.4 T EG027C42
    CK15F050  C2015 04 06.93844 23 40 26.38 +17 13 12.9          11.0 T EG027C42
    CK15F050  C2015 04 06.93963 23 40 27.02 +17 13 24.7          11.7 T EG027C42
    CK15F050  C2015 04 06.94083 23 40 27.42 +17 13 36.8          10.7 T EG027C42
    CK15F050  C2015 04 06.94203 23 40 28.06 +17 13 48.7          11.4 T EG027C42
    CK15F050  C2015 04 07.15674 23 42 03.82 +17 51 03.6          11.4 TqEG027C10
    CK15F050  C2015 04 07.15934 23 42 05.02 +17 51 31.5          11.4 TqEG027C10
    CK15F050  C2015 04 07.16225 23 42 06.37 +17 52 00.6          11.3 TqEG027C10
    CK15F050  C2015 04 07.16514 23 42 07.70 +17 52 31.0          11.2 TqEG027C10
    CK15F050  C2015 04 07.16861 23 42 09.24 +17 53 08.4          11.2 TqEG027C10
    CK15F050  C2015 04 07.87550 23 47 49.67 +19 59 05.1          11.4 TqEG027O75
    CK15F050  C2015 04 07.87573 23 47 49.74 +19 59 07.2          11.0 TqEG027O75
    CK15F050  C2015 04 07.87620 23 47 49.93 +19 59 13.0          11.6 TqEG027O75
    CK15F050  C2015 04 07.87666 23 47 50.21 +19 59 18.3          11.5 TqEG027O75
    CK15F050  C2015 04 07.87805 23 47 50.83 +19 59 33.7          11.5 TqEG027O75
    CK15F050  C2015 04 07.87944 23 47 51.56 +19 59 49.5          10.2 TqEG027O75
    CK15F050  C2015 04 07.87990 23 47 51.77 +19 59 55.0          10.4 TqEG027O75
    CK15F050  C2015 04 07.92928 23 48 17.27 +20 08 57.8          11.9 ToEG027C42
    CK15F050  C2015 04 07.93049 23 48 18.08 +20 09 09.5          11.4 ToEG027C42
    CK15F050  C2015 04 07.93171 23 48 18.65 +20 09 23.8          11.9 ToEG027C42
    CK15F050  C2015 04 07.93292 23 48 19.45 +20 09 34.8          11.4 ToEG027C42
    CK15F050  C2015 04 07.93413 23 48 19.92 +20 09 49.3          11.9 ToEG027C42
    CK15F050  C2015 04 07.93534 23 48 20.38 +20 10 03.6          11.5 ToEG027C42
    CK15F050  C2015 04 07.93655 23 48 20.99 +20 10 17.5          12.0 ToEG027C42
    CK15F050  C2015 04 07.93774 23 48 21.66 +20 10 31.0          11.3 ToEG027C42
    CK15F050  C2015 04 07.93900 23 48 22.34 +20 10 44.0          12.1 ToEG027C42
    CK15F050  C2015 04 07.94021 23 48 22.79 +20 10 56.2          12.2 ToEG027C42
    CK15F050  C2015 04 07.94144 23 48 23.64 +20 11 09.1          12.2 ToEG027C42
    CK15F050  C2015 04 07.94264 23 48 24.03 +20 11 24.4          11.9 ToEG027C42
    CK15F050  C2015 04 07.94385 23 48 24.84 +20 11 38.3          12.3 ToEG027C42
    CK15F050  C2015 04 07.94506 23 48 25.26 +20 11 49.7          11.9 ToEG027C42
    CK15F050  C2015 04 07.94628 23 48 25.95 +20 12 03.2          12.3 ToEG027C42
    CK15F050  C2015 04 07.94748 23 48 26.71 +20 12 15.1          11.4 ToEG027C42
    CK15F050  C2015 04 07.94869 23 48 27.34 +20 12 29.8          12.5 ToEG027C42
    CK15F050  C2015 04 07.94988 23 48 27.89 +20 12 43.1          12.2 ToEG027C42
    CK15F050 KC2015 04 08.15447 23 50 14.07 +20 49 59.8          14.0 TtEG027204
    CK15F050 KC2015 04 08.15570 23 50 14.71 +20 50 13.1                tEG027204
    CK15F050 KC2015 04 08.15692 23 50 15.40 +20 50 26.2                tEG027204
    CK15F050 KC2015 04 08.15815 23 50 15.98 +20 50 40.3                tEG027204
    CK15F050 KC2015 04 08.15937 23 50 16.64 +20 50 54.5                tEG027204
    CK15F050  C2015 04 08.87876 23 56 57.54 +23 04 56.2          12.0 TqEG027O75
    CK15F050  C2015 04 08.87945 23 56 57.95 +23 05 03.8          12.5 TqEG027O75
    CK15F050  C2015 04 08.87968 23 56 58.04 +23 05 06.8          12.6 TqEG027O75
    CK15F050  C2015 04 08.88061 23 56 58.60 +23 05 17.1          11.6 TqEG027O75
    CK15F050  C2015 04 08.88153 23 56 59.16 +23 05 27.7          11.9 TqEG027O75
    CK15F050  C2015 04 08.88177 23 56 59.32 +23 05 30.4          11.9 TqEG027O75
    CK15F050  C2015 04 08.88200 23 56 59.43 +23 05 33.3          12.0 TqEG027O75
    CK15F050 KC2015 04 09.14648 23 59 37.32 +23 55 44.3          14.3 TtEG027204
    CK15F050 KC2015 04 09.14801 23 59 38.27 +23 56 02.0                tEG027204
    CK15F050 KC2015 04 09.14955 23 59 39.23 +23 56 18.7                tEG027204
    CK15F050 KC2015 04 09.15108 23 59 40.21 +23 56 36.7                tEG027204
    CK15F050 KC2015 04 09.15261 23 59 41.05 +23 56 54.5                tEG027204
    CK15F050  C2015 04 09.93587 00 08 04.08 +26 27 49.2          11.8 ToEG027C42
    CK15F050  C2015 04 09.93707 00 08 04.98 +26 28 03.4          11.9 ToEG027C42
    CK15F050  C2015 04 09.93829 00 08 05.82 +26 28 17.1          11.8 ToEG027C42
    CK15F050  C2015 04 09.93950 00 08 06.62 +26 28 32.7          11.8 ToEG027C42
    CK15F050  C2015 04 09.94603 00 08 11.05 +26 29 49.0          11.8 ToEG027C42
    CK15F050  C2015 04 09.94722 00 08 11.81 +26 30 01.3          11.9 ToEG027C42
    CK15F050  C2015 04 09.94841 00 08 12.62 +26 30 12.7          11.9 ToEG027C42
    CK15F050  C2015 04 09.94961 00 08 13.54 +26 30 30.7          11.9 ToEG027C42
    CK15F050  C2015 04 10.12238 00 10 11.40 +27 03 57.6          14.7 TqEG027A71
    CK15F050  C2015 04 10.12355 00 10 12.22 +27 04 16.5          14.8 TqEG027A71
    CK15F050  C2015 04 10.12471 00 10 12.93 +27 04 27.4          14.6 TqEG027A71
    CK15F050  C2015 04 10.12603 00 10 13.91 +27 04 43.2          14.5 TqEG027A71

Observer details:
204 Schiaparelli Observatory.  Observer L. Buzzi.  0.60-m f/4.64 reflector
    + CCD.
247 Roving Observer.  Observer Z.-Q. Guo.  Measurer M.-T. Hui.  0.11-m f/5.0
    refractor + CCD.
A71 Stixendorf.  Observers M. Jaeger,W. Vollmann,E. Prosperi,S. Prosperi.
    Measurer W. Vollmann.  0.25-m f/4 reflector + CCD.
C10 Maisoncelles.  Observer J.-F. Soulier.  0.30-m f/3.8 Newtonian reflector
    + CCD.
C42 Xingming Observatory,Mt. Nanshan.  Observers G. Sun,X. Gao.  Measurers
    G. Sun,S. Yuan,M.-T. Hui.  0.11-m f/.05 reflector + CCD.

O75 ISON-Hureltogoot Observatory.  Observers T. Namkhai,S. Schmalz.  Measurer
    S. Schmalz.  0.4-m f/2.3 reflector + CCD.

Orbital elements:
    C/2015 F5
T 2015 Mar. 28.43081 TT                                 MPCW
q   0.3477981            (2000.0)            P               Q
                   Peri.   15.37040     +0.09218817     -0.86693434
                   Node   288.58304     -0.95937494     -0.20906118
e   1.0            Incl.  148.88448     -0.26664785     +0.45245804
From 75 observations 2015 Apr. 4-10.

Ephemeris:
    C/2015 F5 (SWAN-Xingming)
Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase   m1    m2
2015 03 11    23 38 55.9 -13 31 59   1.5418  0.5921    10.3    17.5  14.2
...
2015 03 26    23 13 23.7 -05 10 25   1.1399  0.3550    17.5    57.9  11.3
...
2015 04 03    23 19 40.3 +07 14 08   0.8308  0.3832    21.8   104.8  10.9
...
2015 04 09    23 58 08.2 +23 27 57   0.6553  0.4773    23.4   123.5  11.4
2015 04 10    00 08 46.6 +26 40 12   0.6366  0.4959    24.3   123.9  11.5
2015 04 11    00 20 54.0 +29 55 46   0.6216  0.5150    25.4   123.4  11.6
...
2015 04 17    02 07 10.8 +46 58 02   0.6130  0.6355    37.3   107.0  12.5
...
2015 04 25    04 54 18.4 +52 16 41   0.7738  0.8001    51.4    79.4  14.0
...
2015 05 10    07 06 05.9 +43 51 43   1.2580  1.0978    56.6    50.2  16.4

Gareth V. Williams           (C) Copyright 2015 MPC           M.P.E.C. 2015-G27