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IAUC 2804: CI Cyg; 1975d

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IAUC number 

                                                  Circular No. 2804
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK
Western Union: RAPID SATELLITE CAMBMASS


CI CYGNI
     S. Tapia, Steward Observatory, writes: "Observations in the
optical region of CI Cyg during its recent outburst (IAUC 2788)
show variable percentage (P) and position angle (theta) of linear
polarization.  The following data are reported:

   1975 UT        P       theta   dB    1975 UT        P       theta    dB
   June 21  0.73 +/- 0.02  123o  0.27   July 14  1.14 +/- 0.08  108o    -
        22  0.60 +/- 0.01  110   0.20        15  1.16 +/- 0.01  105    0.35
        23  0.73 +/- 0.02  104   0.26

dB (uncertainty +/- 0.04) indicates the difference in B magnitudes,
CI Cyg minus BD +35 3825.  The nolarimeter consists of an achromatic
halfwave plate rotating in front of a Wollaston prism.  The
spectral region for polarimetry was limited by an S-11 spectral
response without filter.  The 154-cm (June 21 to July 14) and 229-cm
(July 15) reflectors of the University of Arizona were used."

     J. Bortle, Brooks Observatory, provides the following visual
magnitude estimates: Apr. 28.2 UT, 11.0; May 10.3, 10.7; 26.1, 10.0;
June 11.1, 9.4; 19.1, 9.3.


COMET BRADFIELD (1975d)
     The following precise positions have been reported:

     1975 UT             R. A. (1950) Decl.        Observer
     May  28.70694     6 31 50.16   - 1 34 41.6    Hers
     June 17.29541     7 36 22.28   + 2 36 08.2    Gilmore
          18.28909     7 39 20.14   + 2 45 47.9      "
          18.29545     7 39 22.25   + 2 45 52.6      "

J. Hers (Randburg, near Johannesburg).  20-cm reflector.
A. C. Gilmore (Carter Observatory).  Measurer: Pamela M. Kilmartin.

     Mr. S. W. Milbourn, British Astronomical Association, provides
the following improved parabolic orbital elements, derived from 42
observations (with residuals < 5") March 18 to May 19:

       T = 1975 Apr. 4.5684 ET   Peri. = 264.1196
                                 Node  = 157.2157   1950.0
       q = 1.216686 AU           Incl. =  55.2545


1975 July 22                   (2804)              Brian G. Marsden

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