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IAUC 4986: 1990b; Mkn 421

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IAUC number 

                                                  Circular No. 4986
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 or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN


COMET CERNIS-KIUCHI-NAKAMURA (1990b)
     Improved parabolic orbital elements from MPC 16205, based on
observations Mar. 17-27:

     T = 1990 Mar. 17.296 ET          Peri. = 100.588
                                      Node  = 347.727   1950.0
     q = 1.06849 AU                   Incl. =  48.138

     1990 ET      R.A. (1950) Decl.     Delta      r       m1
     Mar. 30     2 35.00    +50 36.0    1.319    1.089     8.5
     Apr.  4     3 17.17    +51 48.6
           9     4 01.76    +52 04.5    1.299    1.133     8.6
          14     4 46.28    +51 19.9
          19     5 28.29    +49 39.1    1.322    1.197     8.9
          24     6 06.19    +47 13.2
          29     6 39.38    +44 16.2    1.392    1.277     9.3
     May   4     7 08.05    +41 01.3
           9     7 32.73    +37 39.0    1.502    1.369     9.7

     Total visual magnitude estimates (cf. IAUC 4980):  Mar. 18.17
UT, 8.7 (C. S. Morris, Pine Mountain Club, CA, 20x80 binoculars);
19.82, 7.7 (H. Dahle, Oslo, Norway, 0.20-m reflector); 22.03, 8.2
(J. E. Bortle, Stormville, NY, 10x50 binoculars); 22.85, 7.6 (G.
Keitch, Wrington, Avon, England, 0.05-m binoculars); 24.18, 7.8
(Morris); 24.86, 7.8 (J. D. Shanklin, Cambridge, England, 20x80
binoculars); 27.05, 8.9 (Bortle, 20x80 binoculars).


MARKARIAN 421
     U. C. Joshi, M. R. Deshpande, and N. M. Vadher, Physical
Research Laboraatory, Ahmedabad, telex:  "We made optical (white
light) photopolarimetric observations of the BL Lac object
Markarian 421 on Jan. 23 with the 2.3-m Vainu Bappu Telescope at
Kavalur.  The degree of polarization dropped from 4.2 to 3.0
percent (+/- 0.14 percent) in about 30 min and then increased to
about 4.0 percent in about 80 min.  Rapid fluctuations of about
18.5 min were superimposed on these variations.  When the
polarization dropped to its minimum value, a simultaneous drop in
flux of about 0.4 mag was observed."


1990 March 27                  (4986)             Daniel W. E. Green

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