Central Bureau for Astronomical Telegrams
IAUC 5579: GAMMA-RAY BURSTS; MARS
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Circular No. 5579
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)
GAMMA-RAY BURSTS
A. Claret, E. Jourdain, E. Churazov, M. Gilfanov, on behalf of
the SIGMA/Granat team (Service d'Astrophysique, Centre d'Etudes
Nucleaires de Saclay; Centre d'Etude Spatiale des Rayonnements,
Toulouse; Space Research Institute, Moscow), report: "The SIGMA
telescope onboard the Granat observatory has detected two gamma-ray
bursts in the 35- to 400-keV energy range. The 1-sigma error box
coordinates of these two bursts is approximatively diamond shaped
because the bursts were detected through an interruption in the
passive shield acting as a collimator. The first source was observed
on July 14.545498 UT (signal-to-noise ratio, S/N, was 24.6),
with the following four positions corresponding to the extremities
of the diamond (equinox 1950.0): R.A. = 14h39m24s, Decl. =
-29 27'.6; 14h32m21s, -28 33'.6; 14h39m52s, -30 25'.8; 14h45m36s,
-31 01'.2. The second source was observed on July 23.835513 (S/N =
55), within the following diamond: R.A. = 19h01m46s, Decl. =
+26 48'.0; 19h05m19s, +27 57'.0; 19h04m22s, +26 50'.4; 19h00m27s,
+25 30'.6."
MARS
S. J. O'Meara, Sky & Telescope; and W. Sheehan, St. Paul, MN,
report visual observations of martian dust activity using the 1-m
reflector at Pic du Midi Observatory: "On Aug. 1.21 UT, a diffuse
yellow haze extended over the southern hemisphere from latitude -40
deg to the remnant south polar cap, and from longitude 0 to 100
deg, where it combined with strong limb brightening. The observations
showed the desert regions from Noachis through Argyre brighter
than normal, while Mare Oceanidum and Mare Australe were fully
yellowed with no visible darkening throughout the region, except
for a slight shading just south of Noachis. The remnant south polar
cap was visible through the haze at longitude about 60 deg,
measuring only about 0".2. On Aug. 2.22, the south polar haze
appeared less opaque and the limb brightening had decreased, but a
stringy yellow cloud extended west-east along the southern border
of Mare Erythraeum. An extension of this dust cloud sliced north
through Bosporus and extended into Thaumasia to just west of Solis
Lacus at Nectar. Not much is known about martian dust activity
during southern-hemisphere summer (as is now the case) when the
planet is far from the earth (1992, Sky Tel. 83, 490). Follow-up
observations would be useful to determine the longevity of these
clouds."
1992 August 8 (5579) Daniel W. E. Green
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