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IAUC 4577: X-RAY PULSAR; S Per; Var IN And; N LMC

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                                                  Circular No. 4577
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

     F. Makino and the Ginga Team, Institute of Space and
Astronautical Science, Tokyo, report that the x-ray outburst near the
position of Cep X-4 (IAUC 4575) is due to an x-ray pulsar with a
pulsation period of 66.25 s.  The source shows erratic short-term
variations superposed on the regular pulsations.  The object is
similar to the transient pulsar X0332+52.  The averaged intensity was
still about 100 mCrab as of Apr. 4.

     B. A. Skiff, Lowell Observatory, reports that the steady rise in
brightness noted by R. Stencel (IAUC 4556) has slowed considerably in
the last several weeks, from about 0.010 mag/day in February to near
constancy at the end of March.  This is apparent from the following
representative differential measurements (uncertainty 0.005 mag)
relative to HD 14415, obtained with the Lowell 0.53-m telescope and a
Stromgren y filter: Feb. 8.14 UT, 0.934; 20.13, 0.804; Mar. 1.10,
0.722; 8.13, 0.694; 18.13, 0.678; 27.12, 0.656.

     G. M. Hurst, Basingstoke, England, communicates the following
precise measurement by A. Young, Burwash, of the object reported on
IAUC 4570 from a Mar. 26 exposure with a 0.57-m reflector: R.A. =
2h26m22s.14, Decl.= +39 49'21".0 (equinox 1950.0); a measurement by B.
Manning, Stakenbridge, of a photograph by M. Mobberley yields the end
figures 22s.21, 19".9.  Hurst reports that the object appears on the
Palomar Sky Survey (1951 Dec. 21) at B = 18-19 and on a Papadopoulos
chart (1976 Oct. 19) at mpv = 12.5.  It is absent from the Lick
Atlas chart (1954 Sept. 26), another Papadopoulos chart (1976 Aug. 31,
[13.5) and an exposure by M. Oates (1987 Oct. 29, [14.0).  He suggests
that it is a Mira-type variable with a range of about 10 mag.
     Visual magnitude estimates: Mar. 26.84 UT, 10.8 (Hurst); 27.84,
11.1 (Hurst); 28.78, 11.4 (A. Boattini, Florence, Italy); 31.84, 11.3
(Hurst); Apr. 1.06, 11.0 (C. Scovil, Stamford, CT).

     Visual magnitude estimates by A. Pearce, Woodlands, Western
Australia: Apr. 4.62 UT, 12.4; 5.48, 12.5; 6.50, 12.2.

1988 April 6                   (4577)              Brian G. Marsden

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