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IAUC 2588: Poss. N IN Sgr; 1973f

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                                                  Circular No. 2588
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


POSSIBLE NOVA IN SAGITTARIUS
     A cablegram received from Dr. V. L. Matchett, Brisbane, on
Oct. 24 reported the discovery of a nova, of visual magnitude 11.5
(on Oct. 24.434 UT), 90" northeast of V1017 Sgr.  The Central Bureau
relayed the report to various observers in the southern hemisphere.
On Oct. 25 Dr. P. J. Andrews, Radcliffe Observatory, replied
that the nova was identical with the star LR Sgr, which is
located 5s east and 2'.2 north of V1017 Sgr, and which is presumed
to be a Mira variable with a magnitude range from 14.2 to fainter
than 17 (Innes 1917, Union Obs. Circ. 1, 300; the star is No. 16 in
this reference).
     Now N. V. Vidal and A. J. Kalnajs, Mount Stromlo and Siding
Spring Observatories, report as follows: "Analysis of 18 new and
old plates in V and B confirms Matchett's report of a new nova 1'.5
northeast of nova V1017 Sgr.  Its normal magnitude and color are V
= 14.4, B-V = +1.2.  On Oct. 28.46 UT they were V = 11.40, B-V = +0.6.
The recent activity may have started a few months ago, since
a B plate taken on Feb. 27 shows a definite rise of about 0.8
magnitude.  All estimates have been made using the photoelectric
sequence reported by Vidal et al. on IAUC 2505.  We point out that V
plates taken in 1959 show the location of the nova coincides
with that of an optical double star separated by less than 10" and
about 1 magnitude difference.


COMET KOHOUTEK (1973f)
     The following precise positions have been reported:

     1973 UT             R.A. (1950) Decl.        m1    Observer
     Oct.  5.80035   10 37 22.00   - 1 34 18.3   10     Tsuchiya
           8.83125   10 42 54.46   - 2 10 26.8   10     Seki
           8.83507   10 42 54.56   - 2 10 26.9            "
          18.82803   11 02 44.99   - 4 22 34.2    9.2     "
          18.83882   11 02 46.46   - 4 22 45.2            "
          19.19311   11 03 31.68   - 4 27 47.2   10.5   Lorenzi
          19.19874   11 03 32.47   - 4 27 55.1            "
          21.50833   11 08 33.93   - 5 01 52.6          Giclas
          21.51493   11 08 34.83   - 5 02 00.1            "
          22.82639   11 11 30.94   - 5 21 48.0    8.7   Seki
          22.84271   11 11 33.16   - 5 22 05.3            "

K. Tsuchiya (Asahikawa).  Measurer: T. Urata.
T. Seki (Geisei Station).  From Orient. Astron. Assoc. Comet Bull.
   No. 77.
L. Lorenzi (Pino Torinese Observatory).
H. L. Giclas (Lowell Observatory).  33-cm photographic telescope.

     The following general elements, with allowance made for
perturbations by Mercury to Pluto, have been derived by the
undersigned from 53 observations Jan. 28 to Oct. 22:

                  Epoch = 1973 Dec. 24.0 ET
     T = 1973 Dec. 28.4334 ET         Peri. =  37.8180
     e = 1.000006                     Node  = 257.7719  1950.0
     q = 0.142427 AU                  Incl. =  14.3062

The osculating value of 1/a = -0.000039 +/- 0.000042 (m.e.) AU**-1.
The corresponding barycentric "original" and "future" values are
+0.00036 and +0.000560, respectively.   The indicated corrections
to the ephemeris on IAUC 2577 are as follows:

1973 ET   R. A.  Decl.    1973/74   R. A.  Decl.    1974 ET   R. A.  Decl.

Oct.  5   +0m02  -0'2     Dec. 24   +0m33  +0'6     Mar. 14   +0m03  +0'8
     25   +0.03  -0.4     Jan. 13   +0.21  +1.9     Apr.  3   +0.03  +0.7
Nov. 14   +0.06  -0.5     Feb.  2   +0.13  +1.6          23   +0.02  +0.6
Dec.  4   +0.14  -0.7          22   +0.06  +1.0     May  13   +0.01  +0.6

     At the suggestion of Dr. G. H. Herbig, Lick Observatory,
D. Duncan has searched for possible occultations of faint, early-type
stars.  The following refined predictions (cf. IAUC 2577), by
the undersigned, include some of these stars:

1973/74 UT         Star (SAO, DM)     mv    Sp.      Separation

Nov. 22 00h34m   157535 = -15  3543   7.0   K2     0'9 in p.a. 201
     28 05 52    157882 = -17  3829   7.0   F0     2.7         199
Dec.  2 14 26    181980 = -20  3892   7.0   K0     0.8          18
     17 02 19    183987 = -25 11228   3.0   B2     3.8         183
     19 15 30    184415 = -26 11359   1.1   M1    15.9         179
     29 12 31    187504 = -21  5201   3.6   K0     6.1         166
Jan.  2 06 19    163024 = -18  5503   9.1   A3     0.6         165
      6 11 02    163793 = -15  5755   8.5   F0     2.3         164
      8 09 04    164103 = -13  5837   8.1   A0     2.0         164
     30 21 55    109461 = + 5   104   6.2   G5     2.5         161
Feb.  2 18 45    109677 = + 7   167   6.9   F0     2.3         161
     14 23 32    092812 = +12   292   7.9   B9    <0.01        164

During the Feb. 14 event there will be an occultation by the nucleus.
The area of visibility is not well defined, but present indications
are that it will be from the Bahamas, extending across the
breadth of the Atlantic Ocean near the Tropic of Cancer.


1973 October 31                (2588)              Brian G. Marsden

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