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IAUC 5603: RX J2117.1+3412; 1992 LR

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                                                  Circular No. 5603
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


RX J2117.1+3412
     T. K. Watson, Department of Astronomy, University of Texas,
Austin, reports: "We have discovered that the white dwarf RX
J2117.1+3412 (R.A.= 21h17m07s, Decl.= +34d12'.4, equinox 2000.0; B =
13) is a pulsating variable star.  K. Werner (1992, 8th European
Workshop on White Dwarf Stars, Leicester) reports that the object is a
ROSAT source and a member of the PG 1159-035 spectroscopic class, so
this is the fifth known DOV star and by far the brightest member of
its class.  We observed the star with a high-speed, two-star
photometer on several nights, using Hamamatsu R647-04 (bialkali)
phototubes in unfiltered light on the 2.1-m telescope at the McDonald
Observatory.  We find pulsations with a peak-to-peak amplitude of
about 0.03 mag and a quasiperiod of 850 s.  Each of three 90-120-min
runs during Aug. 20-28 has a power spectrum that shows significant
bands of power between 500 and 900 s, the amplitude of the largest
peak in each power spectrum being 0.007 mag.  There are indications
that the bands of power observed are made up of closely spaced
periodicities, similar to those seen in other DOV stars, but our runs
are not yet long enough to resolve them.  Observers interested in
studying this star should send an e-mail request for a finding chart
to tkw@bullwinkle.as.utexas.edu and include their fax number."


1992 LR
     Continuation to the ephemeris on IAUC 5581:

1992 TT     R. A. (2000) Decl.     Delta      r    Elong. Phase      V
Sept. 5    22 16.07    + 4 11.7    0.162    1.165  165.1   12.9     15.1
     10    22 27.64    + 3 25.8    0.183    1.185  165.6   12.2     15.4
     15    22 37.36    + 2 42.7    0.206    1.206  165.1   12.4     15.7
     20    22 45.72    + 2 04.0    0.232    1.228  163.5   13.4     16.1
     25    22 53.12    + 1 30.7    0.260    1.252  161.2   15.0     16.4
     30    22 59.93    + 1 03.7    0.291    1.277  158.3   16.8     16.7
Oct.  5    23 06.39    + 0 43.4    0.325    1.302  155.2   18.8     17.1
     10    23 12.67    + 0 30.0    0.362    1.328  151.8   20.8     17.4
     15    23 18.88    + 0 23.1    0.401    1.355  148.4   22.7     17.8
     20    23 25.09    + 0 22.3    0.443    1.383  145.0   24.4     18.1
     25    23 31.37    + 0 27.3    0.489    1.410  141.6   26.0     18.4


1992 September 3               (5603)              Brian G. Marsden

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