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IAUC 4600: 1988e, 1988g; ASM 2000+25

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                                                  Circular No. 4600
Central Bureau for Astronomical Telegrams
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

     C. M. Bardwell, Center for Astrophysics, has drawn attention to
the remarkable similarity of the orbits of these two comets (cf. IAUC
4583, 4599).  Improvement of both orbit determinations using new observations
results in even closer agreement, to within 0.3 deg in Peri, Node and Incl.
and to within 0.008 AU in q (with the values of T differing by 76 days); at
least in the case of comet 1988e, e > 0.99.  Visual estimates of comet
1988g on May 19.45 UT by D. Levy (Tucson, AZ, 0.4-m reflector) and by
C. S. Morris (near Mount Wilson, CA, 0.26-m reflector) gave m1 = 11.9
and 13.3, respectively.  Both comets are evidently very diffuse.
Further observations (of all types) would be very useful.

ASM 2000+25
     F. Makino and the Ginga Team, Sagamihara, Kanagawa, communicate
the following measurements (which include revision of the data on IAUC
4587) of the x-ray intensity at 3-6 keV (in units of 10**-8 erg cm**-2
s**-1): Apr. 26.03 UT, 7.28; 26.90, 7.80; 28.41, 8.34; 29.51, 8.14;
May 1.71, 7.94; 2.78, 7.71; 3.92, 7.33; 5.86, 6.35; 6.73, 6.41; 9.67,
6.03; 10.49, 5.98; 11.74, 5.86; 13.34, 5.73.
     R. M. Wagner, A. A. Henden and R. Bertram, Ohio State University;
and S. G. Starrfield, Arizona State University, write: "Spectroscopic
observations (range 450-720 nm, nominal spectral resolution 1.5 nm) of
candidates A and B for ASM 2000+25 (IAUC 4589) were obtained on May 14
and 16, respectively, with the Ohio State University CCD spectrograph
on the Perkins 1.8-m telescope.  The spectrum of candidate A is that
of a late M-type star, since it shows strong TiO and VO bands; no
emission features were present in the spectrum, contrary to the report
on IAUC 4598, which was based on low-dispersion objective-prism
spectra obtained on the same day and in the same spectral region.  The
spectrum of candidate B shows a featureless, slightly reddened
continuum.  No strong emission or absorption lines are present.  This
spectrum is completely analogous to that of V616 Mon = A0620-00 obtained
at maximum in 1975 (Gull et al. 1976, Ap.J. 206, 260).  The lack of an
optical object on archival plates, the presence of a new optical
object that might be associated with the abrupt appearance of a new x-
ray source, the detection of soft x-ray emission and the featureless
appearance of the optical spectrum strongly suggest that candidate B
is the optical counterpart of the x-ray source."

1988 May 19                    (4600)              Brian G. Marsden

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