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                    THE ROYAL ASTRONOMICAL SOCIETY OF CANADA

                            COMET AND NOVA SECTION
                                                              Announcement #11
COMET IKEYA-SEKI (1965f)

This comet, discovered on September 18, is expected to become very bright, and
may be one of the brightest of the century. The following is a modification of
the ephemeris supplied by Michael McCants. Note that it differs from the
ephemeris listed on Announcement #10.

          1965   R.A.1950    Decl.    Mag. Angle   40 N      50 N
        00h U.T.                           from
                  h  m        °   '        sun          Rises
       Oct.  9   10 45.3    -14 07    3.8   33      4.4       4.7
            12   11 17.1    -14 43    2.8   28      4.8       5.2
            13   11 29.0    -14 48    2.4   26      4.9       5.3
            14   11 41.7    -14 50    2.0   24      5.1       5.5
            15   11 55.1    -14 48    1.5   21      5.2       5.6
            16   12 09.3    -14 43    1.0   19      5.4       5.8
            17   12 24.2    -14 37    0.4   16      5.6       6.0
            18   12 40.2    -14 12   -0.5   13      5.8       6.1
            19   12 57.4    -13 40   -1.7   10      6.0       6.3
            20   13 16.0    -12 55   -3.2    6      6.2       6.5
            21   13 38.4    -11 20   -8.8    1      6.3       6.5
            22   13 24.9    -10 53   -4.3    5      5.8       6.1
            23   13 13.4    -11 48   -3.0    9      5.7       5.9
            24   13 04.7    -12 36   -1.7   12      5.5       5.8
            25   12 55.3    -13 21   -0.5   15      5.4       5.7
            26   12 48.2    -14 12    0.6   18      5.2       5.6
            27   12 42.9    -14 58    1.6   20      5.0       5.5
       Nov.  1   12 17.7    -18 27    3.4   30      4.6       5.0
             6   11 56.9    -21 40    4.5   39      4.2       4.7
            16   11 18.5    -27 41    6.0   56      3.3       4.0
            26   10 36.9    -33 04    6.9   72      2.6       3.4
       Dec.  6   09 46.6    -37 11    7.6   88      1.3       low
            16   08 50.2    -39 12    8.3  102      0.2
            26   07 53.9    -38 33    8.9  114     22.4


This comet is related to the Great Sun Grazing Comet of 1882 and its family.
Perihelion occurs on October 21 when the comet passes less than 200,000 miles
from the surface of the sun. In fact, ate set of orbital elements indicates
that the perihelion distance is below the solar surface, so this ephemeris is
doubtful after October 21.

The magnitude is based on:
       Mag. 6.2 + 5log (dist. from earth) + 10log (dist. from sun)
but the actual magnitude could be somewhat different from the listed value. It
appears, however, that the comet will be brighter than Venus when near the sun.

The undersigned has determined the time of "Comet-rise" for 40° and 50° N lati-
tude, and they are listed to the nearest tenth of an hour.  Interpolate or
extrapolate for other latitudes. These are local mean times. To convert to
standard times, see page 12 of the OBSERVER'S HANDBOOK.

Comet and Nova Section - Announcement #11                                       -2-


Since this comet could undergo unexpected changes, members are asked to make as
many observations as possible and report them to the undersigned.    Since cir-
culation of this announcement is limited, would you please inform other members
of the Society about this comet.

Hugh N.A. Maclean of the Niagara Falls Centre reports on an observation of Comet
Ikeya-Seki an October 3:

  "Brightness estimate was 5.0. The Comet's position at 10:30 U.T. Oct.3, was:
   R.A. 09h 57m; Decl. -12° 40'.  The nucleus was bright, but not starlike in
   8" 'scope.   The Coma was small; I would guess around 6' to 8'."


COMET ALCOCK (1965h)

This comet is in the evening sky during the next month and should be visible in
small telescopes. The following ephemeris was obtained from I.A.U. Circular 1926,
and the magnitudes were determined by the undersigned from:
       Mag. = 8.5 + 51og (dist. from earth) + 15log (dist. from sun).
Magnitudes will be approximate, at best.

                    1965     R.A.1950   Decl.    Mag.
                   00h U.T.
                   Oct.  7   17.34.4   +27 15    10.7
                        12   17 55.1   +22 50    10.6
                        17   18 16.1   +18 06    10.5
                        22   18 37.3   +13 12    10.4
                        27   18 58.4   +08 14    10.4
                   Nov.  1   19 19.2   +03 23    10.5
                         6   19 39.7   -01 14    10.6


PERIODIC COMET DeVICO-SWIFT (1678, 1844I, 1894IV, 1965e)

This comet was recovered last July, and is about three to four magnitudes fainter
than predicted in "Bulletin #6", so it will not be visible in small telescopes.


NOVA HERCULIS, 1963

This nova is now declining very slowly in brightness. Mr. Maclean of the Niagara
Falls Centre estimated the magnitude at 13.8 on August 24, 1965.  The position
of this nova is R.A. 18h 12m 46s, Decl. 41° 50.'4 (1950).


                Members may have copies of the instruction forms
                                   upon request.



                                              Jim Low, National Coordinator,
                                              Comet and Nova Section,
                                              Standing Committee an Observational
                                                               Activities,
                                              108 Roy Avenue, Apt. 102,
October 7, 1965.                              Dorval, P.Q.