Electronic Telegram No. 3069
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 P/2012 F5 (GIBBS)
     A. R. Gibbs reports his discovery of a comet on CCD images obtained in
good seeing with the Mount Lemmon 1.5-m reflector (discovery observations
tabulated below); four co-added 30-s exposures show a stellar coma and a long,
narrow tail of length 7'.3-7'.4 in p.a. 292.5 deg.  After posting on the
Minor Planet Center's NEOCP webpage, other CCD astrometrists have also noted
the object's cometary appearance.  Bringfried Stecklum (Thueringer
Landessternwarte, Tautenburg, Germany) writes that five co-added 180-s R-band
frames (pixel scale 1".2) obtained on Mar. 22.89 UT with the 2-m Tautenburg
Telescope in its Schmidt configuration (diameter of the correction plate 1.34
m, f/2) yield a starlike coma of magnitude 18.3 with an extremely narrow and
completely straight tail extending to at least 8'.5 that emerges from an
elongated core (the latter being only marginally wider than the stellar
images).  Luca Buzzi finds a very straight, narrow tail at least 6'.5 long in
p.a. 292 deg on stacked images taken in good seeing with a 0.60-m f/4.6
reflector at Varese, Italy, on Mar. 23.0; astrometry was difficult because
the nuclear condensation is only slightly brighter than the tail.  H. Sato
(Tokyo, Japan) remotely obtained images with a 0.25-m f/3.4 astrograph at the
RAS Observatory near Mayhill, NM, U.S.A., on Mar. 23.2; seven stacked 120-s
exposures show a diffuse coma 20" in diameter with a total V-band magnitude
(as measured within a circular aperture of radius 10") of 18.1.  Sato took
follow-up images with a 0.51-m f/6.8 astrograph at the same site on Mar.
25.3, showing a diffuse 10" coma and a straight tail 10' long toward p.a. 300
degrees.  W. H. Ryan finds a narrow, distinct tail > 2' long in p.a. about
300 deg on R-band images taken on Mar. 23.3 with the Magdalena Ridge
Observatory 2.4-m f/8.9 reflector; follow-up observations by W. H. Ryan with
E. V. Ryan on Mar. 24.25-24.38 show a narrow, distinct tail > 4' long in p.a.
about 300 deg.  P. Birtwhistle (Great Shefford, Berkshire, England; 0.40-m
f/6 reflector) finds a very concentrated nuclear condensation 6" in diameter
with a very thin, very straight tail at least 9'.5 long (to the edge of the
field) in p.a. 292 deg on his images from Mar. 24.0; his follow-up images
taken on Mar. 25.05-25.06 show a central condensation 8" in diameter (less
distinct than the previous night, and difficult to measure) with a straight,
thin tail 7'.5 long in p.a. 292 deg (the first 4'.5 being significantly
brighter than the last 3').  Images taken by M. Masek, J. Cerny, J. Ebr, M.
Prouza, P. Kubanek, and M. Jelinek with a 0.3-m f/10 reflector at the Pierre
Auger Observatory at Malarguee, Mendoza, Argentina, on Mar. 24.0 show a tail
160" long in p.a. 295 deg.  T. Vorobjov reports that six stacked 120-s
exposures taken on Mar. 24.25-24.26 with the Kitt Peak 1.3-m f/13 Cassegrain
reflector shows a 3'30" tail in p.a. 290 deg.  Michal Zolnowski (Krakow,
Poland) and Michal Kusiak (Zywiec, Poland) found a 5' tail in p.a. 290 deg
on images taken on Mar. 24.94-24.96 with a 0.4-m reflector.  Jean-Francois
Soulier (Maisoncelles, Seine et Marne, France, 30-cm f/4 reflector; Mar.
25.03-25.06) finds a 7' tail.  G. Hug (Scranton, KS, U.S.A., 0.56-m
reflector + CCD, Mar. 25.3) measured a bright, narrow tail 7'-8' long in
p.a. about 290 deg.  E. Guido, N. Howes, and G. Sostero stacked seven 300-s
unfiltered exposures taken with a 0.3-m reflector on Mar. 25.8 through a
0.3-m f/4.7 reflector at Povoletto, Italy, showing it to be elongated
with a narrow tail at least 30" long toward p.a. 300 deg; the central
condensation is very difficult to locate, hampering precise astrometric
measurement.

     2012 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar. 22.28771   11 15 10.24   - 5 33 32.0          Gibbs
          22.28943   11 15 10.20   - 5 33 31.5            "
          22.29118   11 15 10.09   - 5 33 30.7            "
          22.29289   11 15 10.05   - 5 33 29.9            "
          22.39053   11 15 05.89   - 5 32 47.6   18.1     "
          22.39427   11 15 05.78   - 5 32 46.3            "
          22.39784   11 15 05.62   - 5 32 44.7            "
          22.40141   11 15 05.46   - 5 32 42.9            "

The available astrometry, the following preliminary elliptical orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2012-F87.

     T = 2010 Sept.15.2693 TT         Peri. = 189.5925
     e = 0.384251                     Node  = 205.3500  2000.0
     q = 1.876522 AU                  Incl. =  13.4844
       a =  3.047544 AU    n = 0.1852589    P =   5.32 years


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

                         (C) Copyright 2012 CBAT
2012 March 25                    (CBET 3069)              Daniel W. E. Green