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IAUC 4537: AMMONIA MASER FLARE IN W51; METHANOL MASER EMISSION IN NGC 6334F; 1987p

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                                                  Circular No. 4537
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444


AMMONIA MASER FLARE IN W51
     S. C. Madden, Five College Radio Astronomy Observatory; P.
Friberg, Onsala Space Observatory; and R. Brown and P. Godfrey,
Monash University, telex:  "We find pronounced variability in NH3
(9,6) maser sources observed Jan. 4 and 5 using the National Radio
Astronomy Observatory 43-m antenna at 18.3 GHz.  Variations in
intensity occur for all of the multiple velocity components toward
the two H2O maser centers W51N (R.A. = 19h21m22.0, Decl. =  +14 25'20",
equinox 1950.0) and W51 Main (R.A. = 19h21m26.0, Decl. = +14 24'42"), with
the greatest variation seen in the 55.7-km/s component originating
toward the latter position; this component shows an increase in
intensity by a factor of 10 since last observed at NRAO in 1985 Dec.
(now estimated to be 28 Jy).  Among other sources demonstrating
variability, W49N (R.A. = 19h07m49.5, Decl. = +9 01'15") now exhibits a
maser source at 0.3 km/s only, whereas components were only observed
at 4.9 or 11.8 km/s during previous observations.  Observed
several times since their first detection in 1984 Nov., these are
the first reported signs of variability in NH3(9,6) masers."


METHANOL MASER EMISSION IN NGC 6334F
     A. D. Haschick, Haystack Observatory; and W. A. Baan, Arecibo
Observatory, write:  "We report detection, with the Haystack 36.6-m
antenna, of intense maser emission in the 6(sub)2-5(sub)3 A+ transition of
methanol at 38.45269 GHz in NGC 6334F at the following position:  R.A.
= 17h17m32.3, Decl. = -35 44'40" (equinox 1950.0).  The source had, on
Jan. 9, a peak flux density of 160 Jy, and exhibited only a single
feature of one-half-power linewidth = 0.6 km/s and velocity (with
respect to local standard of rest) = -4.9 km/s.  Weaker emission at
this frequency was also detected in W3(OH) with a flux of 7.5 Jy,
width of 2.4 km/s, and velocity of -41.1 km/s."


PERIODIC COMET BORRELLY (1987p)
     Total visual magnitude estimates (B = binoculars):  Jan. 9.80
UT, 7.7 (M. V. Zanotta, Milan, Italy, 20x80 B); 10.81, 8.1 (J. D.
Shanklin, Cambridge, England, 10x80 B); 12.94, 8.7 (P. Schmeer,
Bischmisheim, W. Germany, 0.20-m reflector); 14.16, 7.7 (C. E.
Spratt, Victoria, BC, 11x80 B); 21.23, 7.7 (A. Hale, Las Cruces,
NM, 10x50 B); 22.15, 8.5 (C. S. Morris, Whitaker Peak, CA, 20x80
B); 24.13, 8.4 (Spratt, 0.20-m reflector).


1988 January 27                (4537)            Daniel W. E. Green

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