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IAUC 2980: 1976e; 3U 0833-45; GU Sgr; WRA 977

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                                                  Circular No. 2980
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.

     The following positions are from the Japan Astronomical Circular
No. 64:

     1976 UT             R. A. (1950) Decl.        Observer
     June 30.62129    18 59 43.88   +22 04 14.3    Koishikawa
          30.68003    18 59 48.14   +22 04 14.6      "
     July  2.62639    19 02 35.13   +22 04 38.4      "
          21.63194    19 44 58.87   +17 02 55.6    Urata
          21.63825    19 45 00.09   +17 02 41.5      "

N. Koishikawa (Sendai Observatory, Ayashi Station).  20-cm f/5.5
T. Urata (JCPM Yakiimo Station).  11-cm f/5.6 camera.

     J. S. Neff and D. A. Ketelsen, Department of Physics and
Astronomy, University of Iowa, report observations on July 25.2 and
26.2 UT with a photoelectric spectrophotometer (3200-5800 A).  The
flux distribution corrected for sky showed a continuous spectrum
similar to that of the sun on which emission bands of CN, C2 and
C3 are superimposed.  The CN, C3, and C2 5165 A bands have strengths
similar to that of the continuum.  The C2 4695 A and 5438 A are about
half the strength of the continuum.  The monochromatic magnitude
at 5500 A was 11.3 on July 25 and 10.8 on July 26.

     P. Wehinger and S. Wyckoff, Royal Greenwich Observatory, report
that image-tube spectra (4200-6300 A, dispersion 40 A/mm)
taken with the 249-cm reflector on August 1.0 UT display strong
bands of C2 (Delta-v = +2, +1, 0, -1) and NH2 (8-0 through 12-0)
extending more than 1' on either side of the nucleus. The 4315 A band
of CH and a weak continuum, less than 0'.2 wide, are also present.

     J. E. Bortle, Brooks Observatory, communicates: "The brightness
surge of the comet (IAUC 2900) is in progress.  It began earlier
than expected and appears to resemble the very large surge of
the 1870 apparition.  The comet could be much brighter than
predicted, reaching magnitude 5 or perhaps even 4 by the date of
perihelion.  After perihelion the comet might be 1 magnitude brighter
than given on IAUC 2900."

     C. S. Morris, Pennsylvania State College, remarks that the
comet is changing its appearance very rapidly.  On July 27.2 UT it
was of magnitude 6.9, had a coma 21' in diameter (in 12 x 50 binoculars),
and displayed four different tails (in a 15-cm f/4 reflector),
three of them straight and narrow.  Their lengths and position
angles were 16', 84o; 30', 116o; and 20', 261o, respectively.
The fourth tail was a broad fan, 20' long and centered in p.a. 158o.

     Selected total visual magnitude estimates and coma diameters:
July 18.13 UT, 9,3, 6' (Morris, 15-cm reflector); 19.14, 9.6, 6'
(Morris); 23.11, 7.9, 15' (Bortle, 10 x 50 binoculars); 23.17, 8.8,
10' (S. O'Meara, Harvard College Observatory, 23-cm refractor; 10'
tail in p.a. 270o); 25.15, 8.8, 3' (P. L. Collins, Concord, Massachusetts,
12-cm refractor); 25.26, 8.5, 9' (Morris, 12 x 50 binoculars;
11'; broad tail in 325o-10o); 26.11, 7,7, 13'.5 (Bortle); 26.22,
7.8, 12' (Morris; 45' tail in 10o); 27.11, 7.6, 14' (Bortle; 1o
tail in 325o); 28.20, 7.5, - (O'Meara); 29.08, 6.7, 15' (Bortle;
0o.5 tail in 310o); 30.18, 8.9, - (P. Maley, Houston, Texas, 13-cm
refractor); 31.16, 8.7, - (Maley); Aug. 1.17, 8.7, - (Maley); 2.18,
8.6, - (Maley).

3U 0833-45
     A. Smith, Department of Physics, University of Leicester,
reports: "The Ariel 5 sky survey has observed an x-ray flare
apparently coincident with 3U 0833-45.  The 2.4-18 keV intensity rose
to a peak of 16.5 +/- 2 cts/s on 1976 July 23.821 UT, a three-fold
increase over the normal level.  The event lasted about 12 hours.
Although a field source transient cannot be ruled out, the number
of such events makes this unlikely."

     F. Bateson, Royal Astronomical Society of New Zealand, cables
that according to the observations by M. Morel this variable was
fading from visual magnitude 10.8 on June 30 to 11.1 on July 6, and
to 11.7 on July 21.  J. Mattei, American Association of Variable
Star Observers, informs us that D. Hoffleit, Maria Mitchell
Observatory, confirms the slow decline photographically.

WRA 977
     H. Mauder and M. Ammann, Astronomisches Institut der Universitat
Tubingen, write that coude spectra of this optical counterpart
of 3U 1223-62 obtained with ESO's 152-cm telescope show radial velocity
variations in the He lines.  H-beta and H-gamma show strong P Cygni
line profiles, the stellar wind velocity being about -180 km/s.
The spectrographic orbital solution and the photoelectric observations
yield coinciding ephemerides for the binary orbit.  If the
inclination is not too low, x-ray eclipses can be expected with the
periodicity of 20d.55 measured from the epoch 1976 Apr. 4.9 UT.

1976 August 4                  (2980)              Zdenek Sekanina

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