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IAUC 7014: XTE J1946+274 = GRO J1944+26; C/1998 P1

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                                                 Circular No. 7014
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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XTE J1946+274 = GRO J1944+26
     D. A. Smith, Massachusetts Institute of Technology (MIT); and
T. Takeshima, Goddard Space Flight Center (GSFC), NASA, on behalf
of the RXTE/ASM and PCA teams at MIT and GSFC, communicate:  "The
ASM on RXTE has detected emission from a location that overlaps the
previous localization of the 1976 Ariel V transient 3A 1942+274
(Warwick et al. 1981,  MNRAS 197, 865; galactic latitude +1.7 deg).
The corners of the ASM 6' x 26' error region are at R.A. = 19h47m.1,
Decl. = +27o16'; 19h46m.2, +27o25'; 19h45m.5, +27o25'; 19h46m.2,
+27o18' (equinox 2000.0; 90-percent-confidence total error).  The
source first came to our attention at about 90 mCrab (2-12 keV) on
Sept. 15.91 UT, with a very hard spectrum.  A retroactive search
reveals that the 1-day average intensity has been rising from 13
mCrab on Sept. 5 to 60 mCrab on Sept. 15.  The RXTE/PCA observed
this location on Sept. 16.02 and recorded an intensity of about 110
mCrab (2-60 keV) with a very strong 15.83-s (+/- 0.02 s) pulsation.
The pulse profile is double-peaked, with a pulse fraction of about
29 percent.  There is, to our knowledge, no previous report of
pulsations from 3A 1942+274.  If this is a reoccurrence of the
Ariel source, the 8' x 52' Ariel position restricts the location to
the westernmost 5' of the ASM region (see
http://xte.mit.edu/~dasmith/x1946_map.gif).  Further PCA
observations are in progress.  Observations at other wavelengths
are encouraged."
     C. A. Wilson, M. H. Finger, R. B. Wilson, and D. M. Scott,
Marshall Space Flight Center, NASA, report for the BATSE team:
"Pulsations from a previously-uncatalogued x-ray pulsar in the Vul-
Cyg region have been detected with BATSE in the energy band 20-50
keV from Sept. 8 through Sept. 14.  A preliminary location (95-
percent confidence) is bounded by R.A. = 19h34m to 19h54m and Decl.
= +22o.5 to +30o.5 (equinox 2000.0).  GRO J1944+26 rose from a 20-
50-keV rms pulsed flux of < 15 mCrab on Sept. 7  to 27 +/- 3 mCrab
on Sept. 13.  Observations between Sept. 8 and 14 are consistent
with a barycentric pulse frequency of 0.06315331(6) Hz on Sept.
11.0 UT, with a frequency derivative of 2.2(2) x 10E-12 Hz/s.  The
pulse profile in the band 20-50 keV has a single asymmetric peak."

     Visual m_1 estimates:  Aug. 26.38 UT, 7.6 (P. Williams,
Heathcote, N.S.W., 20x80 binoculars); Sept. 6.40, 7.4 (J. Shanklin,
Hobart, Tasmania, 10x50 binoculars); 15.40, 8.2 (D. A. J. Seargent,
The Entrance, N.S.W., 25x100 binoculars).

                      (C) Copyright 1998 CBAT
1998 September 16              (7014)            Daniel W. E. Green

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