Some results have been published in IAU Circular 6495 (1996-Oct-19):
COMET C/1996 Q1 (TABUR)
K. Dennerl, J. Englhauser, and J. Truemper, Max-Planck-
Institut fuer Extraterrestrische Physik, Garching; and C. Lisse,
Goddard Space Flight Center, NASA, communicate: "X-ray emission
from comet C/1996 Q1 was detected with the ROSAT High Resolution
Imager. The observations were performed on several occasions
between Sept. 26 and Oct. 6, when Delta = 0.51-0.42 AU and r =
1.09-0.99 AU. The x-ray emission was highly variable on time
scales of hours (or less), both in intensity (at least by a factor
of five) and morphology, with episodes of considerable deviation
from the crescent shape of C/1996 B2 (Hyakutake) observed under
similar phase angles (IAUC 6373). The brightest parts of the
emission were always concentrated in an area with a typical extent
of 5' (90 000 km) and displaced sunward from the nucleus by about
100" (30 000 km). They reached a peak surface brightness of 0.01
count sE-1 arcminE-2, similar to that of comet C/1996 B2 during its
close approach to the earth in Mar. The rapid morphological
changes seem to rule out any scattering of solar x-rays by material
in the comet's coma as the dominant mechanism for producing the
bright parts of the x-ray emission."
ROSAT observations of comet Tabur in Sept./Oct. 1996:
============================================================================================= ROR date start dur R.A. Dec. Weilheim contacts / ROSAT observations yymmdd sec sec deg deg (UT) (UT) --------------------------------------------------------------------------------------------- 180151 960925 69643 540 97.384 21.949 180152 960926 63404 631 99.034 23.895 180152 960926 66164 1786 99.034 23.895 180153 960926 74880 823 99.335 24.248 no 180153 960926 80700 763 99.335 24.248 180154 960927 62991 979 101.022 26.154 Weilheim 180154 960927 68794 1140 101.022 26.154 180155 960927 74450 1320 101.290 26.456 contacts 180155 960927 80253 1260 101.290 26.456 180156 960928 74113 1317 103.367 28.691 180157 960928 79842 1318 103.587 28.926 180157 960928 85575 1315 103.587 28.926 ............................................................................................. 180159 961006 36570 2344 129.450 47.560 10:21:43 - 10:28:57 / 10:09:30 - 10:48:34 180160 961006 42420 2170 129.795 47.714 11:59:08 - 12:09:09 / 11:47:00 - 12:23:10 180161 961006 48075 2275 130.122 47.861 13:38:49 - 13:48:41 / 13:21:15 - 13:59:10 180162 961006 53020 3060 130.415 47.992 15:18:50 - 15:28:38 / 14:43:40 - 15:34:40 ============================================================================================= Information from the ephemeris: Date: Sep 25 Sep 28 Oct 06 --------------------------------------------------------- Heliocentric distance (AU): 1.11 1.07 0.99 Geocentric distance (AU): 0.53 0.49 0.42 Visual magnitude (coma) (mag): 6.6 6.2 5.6
ASCA observation of comet Tabur in September 1996:
----------------------------------------------------------------------------- A S C A WEEKLY OBSERVATION PLAN ----------------------------------------------------------------------------- September 18 - 27 ver-1 (96/09/04) (ISAS contact scientist: M. ISHIDA ishida@astro.isas.ac.jp) ----------------------------------------------------------------------------- Date MNV Target Tag. Exp. Observation PI or start name Cat. (ks) Cat. Pri./TC ( PPI/Co-PI) ----------------------------------------------------------------------------- 9/25 13:20 Comet Tabur Star 20 JPN TOO Nagase /ASCA team ----------------------------------------------------------------------------- (Note) Obs. Cat. JPN: Japan time, US: US time, JUS: Japan-US Collaboration, USJ: US-Japan Collaboration, MJU: Merged Japan-US (PPI=Japan), MUJ: Merged US-Japan (PPI=US), ESJ: ESA-Japan Program, MOT: Manager's observatory time (Calibration and maintenance)
