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IAUC 5372: X Per; EF Peg; 1991t

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                                                  Circular No. 5372
Central Bureau for Astronomical Telegrams
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

     R. Corbet and B. Thomas, Pennsylvania State University, report:
"Spectra obtained of X Per at the Black Moshannon Observatory on
Oct. 16 and 18 clearly show the presence of a double-peaked emission
line at H-alpha.  This contrasts with the absorption line reported
earlier by Norton et al. (1991, preprint).  X Per thus appears to
have re-entered an active state."

     S. B. Howell, Planetary Science Institute; and R. Fried,
Braeside Observatory, communicate:  "Photoelectric observations made
with the Braeside Observatory 0.4-m reflector yield the following
mean magnitudes (+/- 0.2 mag) and colors for EF Peg: Oct. 17 UT, V =
11.6, B-V = -0.66, U-B = -0.95; Oct. 18, 11.7, -, -; Oct. 19, 11.9,
-0.65, -0.89; Oct. 20, 11.9, -0.68, -0.98.  We note that EF Peg lies
about 5" from a star of mag 14, in p.a. 290 +/- 5 deg.  In addition,
superhumps were seen with peak-to-peak amplitudes ranging from possibly
0.05 mag on Oct. 17 to as large as 0.21 mag on Oct. 19.  A bestfit
superhump period for these data is 0.091 +/- 0.01 day, in agreement
with that found by Kato and Takata (IAUC 5371).  The appearance
of superhumps in the outburst lightcurve of EF Peg places this star
in the SU UMa subclass of dwarf novae and allows us to estimate its
orbital period at about 2.1 hr.  This period would make EF Peg only
the second SU UMa star found to lie within the cataclysmic variable
period gap.  Details of these observations will be published
     Visual magnitude estimates by P. Schmeer, Bischmisheim, Germany
(cf. IAUC 5369):  Oct. 18.00 UT, 11.2; 19.77, 11.3; 21.79, 11.5.

     Total visual magnitude estimates (cf. IAUC 5359): Oct. 7.84 UT,
8.3 (A. Pearce, Scarborough, W. Australia, 20x80 binoculars); 9.39,
8.0 (J. E. Bortle, Stormville, NY, 20x80 binoculars); 12.51, 8.8 (C.
Spratt, Victoria, BC, 0.20-m reflector); 16.23, 8.1 (A. Pereira,
Cabo da Roca, Portugal, 9x34 binoculars); 19.49, 8.8 (A. Hale, Las
Cruces, NM, 10x50 binoculars); 20.18, 8.0 (J. Jahn, Bodenteich,
Germany, 0.06-m refractor).

1991 October 24                (5372)             Daniel W. E. Green

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