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IAUC 3221: Occn OF SAO 85009 BY (2); Poss. SN IN MCG -4-32-23; Poss. OPTICAL COUNTERPART OF 2S 1702-363; Mk 421 = 2A 1102+384; 1978b

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                                                  Circular No. 3221
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK     Telex: 921428
Telephone: (617) 864-5758

     Recent predictions received from G. E. Taylor, H.M. Nautical
Almanac Office, and from D. W. Dunham, Silver Spring, Maryland,
indicate that the calculation by Wasserman and Franz (IAUC 3141) is
essentially correct.  Occultation time ranges from 5h21m UT off the
eastern coast of North America to 5h27m UT off the western coast.
Last-minute astrometric observations that could improve the predictions
should be communicated forthwith, preferably by telex, either
to U.K. telex 87451 (answerback RGOBSY G) URGENT ATTN. G. TAYLOR
HMNO, or to U.S.A. telex 89675 (answerback NASCOM GBLT) URGENT ATTN.
W. WARREN, CODE 601, NSSDC.  Last-minute predictions will be available
by telephoning Mr. Taylor during May 28d13h-28d16h UT at U.K.
032-181-3255 or by telephoning Dr. Dunham on May 27 or 28 at U.S.A
301-585-0989.  Owing to the absence abroad of the undersigned, the
Central Telegram Bureau will not be able to relay astrometric
observations or to provide last-minute predictions.

     G. Gilmore, Department of Physics, University of Canterbury,
reports the discovery of a possible supernova 20" due west of the
nucleus of a fifteenth-magnitude galaxy, presumably MCG -4-32-23,
located at R.A. = 13h27m.5, Decl. = -21o29' (equinox 1950.0).  The object,
of magnitude about 17, appeared on May 8 and 9 as a distorted or
secondary nucleus of the galaxy.  It was not visible on exposures
obtained on Mar. 9 and Apr. 8.

     E. J. Zuiderwijk, University of Amsterdam and European Southern
Observatory, reports: "On May 8.3 UT a blue stellar object was
seen in the vicinity of the x-ray source 2S 1702-363.  The object
was discovered during spectroscopic observations at the Cassegrain
focus of the 360-cm E.S.O. reflector.  It was clearly visible on
the integrating television guiding system and was brighter than the
stars marked 1 and 2 in the finding chart given by Jernigan et al.
(1978, Nature 272, 701).  Its position is 8' east of star 2.  Tests
with blue and visual filters showed that the object was very blue
(magnitude ~ 16.5).  However, the object is not visible on either
an ultraviolet or an H-alpha plate (38 A) taken at the prime focus of
the 360-cm reflector on May 6.3 UT, even though star 1 is clearly
visible on both plates.  The object is also not present on the
E.S.O. "quick blue" sky survey.  An image-tube spectrogram (dispersion
114 A/mm) revealed a featureless spectrum with some indication
of emission at H-beta."

Mk 421 = 2A 1102+384
     G. J  Fishman, National Aeronautics and Space Administration,
writes that the HEAO-1 spacecraft is scheduled to observe the BL
Lac object Mk 421 = 2A 1102+384 during May 28d03h-28d12h UT.
Optical and radio monitoring of the source near this time would be
desirable.  HEAO-1 pointed observations are continuing to be made
about 5 times per week for intervals of 3 to 9 hours.

     F. Walter and K. O. Mason, University of California at Berkeley;
and G. Garmire, California Institute of Technology, report
that the HEAO low-energy detectors have also observed a soft source
near Mk 421 on serveral scans during 1977 Nov. 23-25 (cf. IAUC
3212).  The 0.2-2.0-keV flux was ~ 10**-10 erg cm**-2 s**-1, while a
thermal bremsstrahlung spectral fit yielded a temperature in the
range 2 to 5 x 10**6 K and NH = 1 to 4 x 10**20 atoms cm**-2. The 94-percent
error-box coordinates are: R.A. = 11h02m00s, Decl. = +38o29';
11h01m26s, +38o16';10h59m10s, +38o29'; 10h59m43s, +38o42' (equinox
1950.0).  Mk 421 lies on the edge of this box.

     Further precise positions have been reported as follows:

     1978 UT             R. A. (1950) Decl.       Mag.   Observer
     Feb.  8.89723     5 15 53.76   +20 28 03.6   12     Clough
           9.07987     5 15 54.89   +20 28 35.4          Penhallow
          10.10589     5 16 01.90   +20 31 31.0            "
          12.07568     5 16 23.42   +20 37 14.9            "
     Apr.  5.8882      6 22 17.60   +23 03 16.8  ~12.5   Manning
          12.8802      6 37 42.23   +23 06 49.1  ~12.5     "
          12.8948      6 37 44.0    +23 06 52              "

H. Clough and R. H. McNaught (Macnairston Observatory) and B.
   Manning (Stakenbridge).  Measurer: P. Birtwhistle.  Communicated
   by G. M. Hurst.
W. S. Penhallow (University of Rhode Island, Quonochontaug Station).
   Measurers: Q. V. Tran and B. M. Ashworth.

     Total visual magnitude estimates: Apr. 13.08 UT9 11.2 (S.
O'Meara, Harvard College Observatory, 23-cm refractor); 15.05, 11.3
(O'Meara); 19.04, 11.3 (O'Meara; fantail 3' long in p.a. 0o-35o);
26.07, 10.7 (J. Bortle, Brooks Observatory, 32-cm reflector); May
1.08, 10.6 (Bortle); 3.06, 11.1 (O'Meara); 8.12, 11.2 (C. S. Morris,
Harvard College Observatory, 23-cm refractor); 11.15, 10.7 (P. L.
Collins, Mount Hopkins, Arizona, 20-cm reflector).

1978 May 18                    (3221)              Brian G. Marsden

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