Central Bureau for Astronomical Telegrams
IAUC 6920: XTE J2012+381; STAR NEAR NGC 4013 = 1989Z?
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Circular No. 6920
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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XTE J2012+381
R. Remillard, A. Levine, and A. Wood, Massachusetts Institute
of Technology (MIT), reporting for the RXTE ASM team at MIT and
Goddard Space Flight Center (GSFC), write: "The RXTE All-Sky
Monitor has detected a transient x-ray source at R.A. = 20h12m.6,
Decl. = +38o11' (equinox 2000.0). The position uncertainty
(90-percent confidence) is approximately +/- 10' in R.A. and +/- 4'
in Decl. In daily averages, the ASM count rate (2-12 keV) was 23
mCrab on May 24.6 UT and 28 on May 25.4, rising to 55 mCrab on May
26.5 and to 88 on May 27.3. The spectrum is becoming softer as the
source brightens. Observations at other wavelengths are urgently
needed."
R. M. Wagner, Ohio State University; S. Starrfield, Arizona
State University; C. Shrader, GSFC; and E. Bowell, B. Skiff, and B.
Koehn, Lowell Observatory, on behalf of the Lowell Observatory Near
Earth Object Search (LONEOS) collaboration, report: "We obtained
several unfiltered images of the RXTE/ASM error box with the LONEOS
Schmidt telescope and CCD camera (field 3.2 x 1.6 deg; scale
2".8/pixel) on May 27.34 UT. Comparison of these images with the
Digital Sky Survey (DSS) reveals a variable stellar object and
possible optical counterpart of XTE J2012+381 within the ASM error
box at R.A. = 20h12m30s.3, Decl. = +38 08'59" (equinox 2000.0;
uncertainty 1" in both coordinates). The object appears on the DSS
at mag about 17-17.5 and is distinctly fainter than a star located
15" to the south. However, the object appears 2-3 mag brighter on
the LONEOS images and comparable in brightness to the stellar
object 15" to the south. No other obviously variable objects or
new objects not present on the DSS were found in the LONEOS images
of the error box."
STAR NEAR NGC 4013 = SUPERNOVA 1989Z?
R. Kushida reports via S. Nakano, Sumoto, Japan, that this
star (cf. IAUC 6911, 6914) has been present with no obvious
variability on her 20 CCD frames of this galaxy taken since 1995.
Y. Kushida has measured the following position of this star from a
CCD frame taken with a 0.40-m f/6 reflector at Yatsugatake South
Base Observatory on 1998 May 23.479 UT (V = 12.6): R.A. =
11h58m32s.06, Decl. = +43o56'53".6 (equinox 2000.0). Images taken
by the Kushidas on 1995 Jan. 10 and 1996 Jan. 3 yield V = 12.5 (and
virtually identical positions). M. Aoki reports (also via Nakano)
that this star is present on his CCD frames taken since 1996; on
1998 May 23.452, he finds V = 12.8 and position end figures 32s.09,
53".6. The Kushidas indicate that this star is very near the
position of SN 1989Z.
(C) Copyright 1998 CBAT
1998 May 27 (6920) Daniel W. E. Green
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