Central Bureau for Astronomical Telegrams
IAUC 5675: 1992t; HR 1469 = NSV 1671; P/SCHWASSMANN-WACHMANN 1
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Circular No. 5675
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
PERIODIC COMET SWIFT-TUTTLE (1992t)
L. K. Deutsch, University of California at Berkeley and Ames
Research Center, NASA; W. F. Hoffmann, University of Arizona; J. L.
Hora, University of Hawaii; J. R. Regester, University of Arizona;
G. G. Fazio, Harvard-Smithsonian Center for Astrophysics; and K.
Shivanandan, Center for Advanced Space Sensing, communicate: "We
report imaging of P/Swift-Tuttle with the UA/SAO/NRL Mid-Infrared
Array Camera (MIRAC; scale 0".67/pixel) and the Steward 2.3-m
telescope at Kitt Peak. Images were obtained between Dec. 9.04 and
9.09 UT. A preliminary analysis gives the following flux levels
and peak surface brightnesses in their respective wavelengths and
bandpasses for the comet in a circular region of diameter 6" centered
on the infrared peak: 49.3 Jy, 6.2 Jy arcsecE-2, 8.8 microns,
0.87 micron; 55.7, 6.1, 9.8, 0.96; 76.8, 7.4, 11.7, 1.13; 66.6,
6.8, 12.5, 1.16. The images were calibrated using the infrared
flux standard alpha Tau. There is no evidence for significant
silicate emission; the four quoted fluxes for the region centered on
the peak are consistent with a 345-K blackbody curve. The strongest
mid-infrared emission extends to the southwest in a tail from
the peak along p.a. 225 deg. This structure is surrounded by
lower-level emission, which encompasses the peak and extends to the
south and west for several arcsec and then begins to curve toward
the southeast. For comparison, the measured surface brightnesses
at a position 6" to the southwest of the peak (p.a. 225 deg) are
1.6 Jy arcsecE-2 (8.8 microns); 1.8 (9.8); 2.1 (11.7); 1.8 (12.5).
Emission to the west, south, and east extended beyond the edges of
our images, which correspond to 18".7 west, 13".9 south, and 20".8
east of the peak in our 11.7-micron image. Emission to the north-
northeast extended only 3"-4" from the peak at all wavelengths.
The minimum detected surface brightness in our 11.7-micron image
was 0.14 Jy arcsecE-2."
HR 1469 = NSV 1671
W. Wenzel, Sonneberg Observatory, reports that no further
minimum (cf. IAUC 5656) and no other conspicuous variability could be
detected on any of 1045 photographs taken from 1928 to 1992 Nov.
1.0 UT.
PERIODIC COMET SCHWASSMANN-WACHMANN 1
H. Mikuz, Ljubljana, Slovenia, provides the following
additional total V magnitudes (cf. IAUC 5674) obtained with 0.2-m
short-focus cameras (+ CCD): Dec. 13.78 UT, 14.1 (2'.5 tail in
p.a. 25 deg); 14.76, 14.3.
1992 December 15 (5675) Daniel W. E. Green
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