Circular No. 5372 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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN X PERSEI 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." EF PEGASI S. B. Howell, Planetary Science Institute; and R. Fried, Brae- side 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 possi- bly 0.05 mag on Oct. 17 to as large as 0.21 mag on Oct. 19. A best- fit superhump period for these data is 0.091 +/- 0.01 day, in agree- ment 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 else- where." 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. PERIODIC COMET HARTLEY 2 (1991t) 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 Daniel W. E. Green Enter L or I or Circ. No.; or Q to quit. 5373 Circular No. 5373 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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN 1991 TF3 C. S. Shoemaker has discovered another fast-moving asteroidal object. The following precise positions are available: 1991 UT R.A. (1950) Decl. Mag. Observer Oct. 2.34600 0 22 18.00 + 6 36 23.0 16.7 Shoemaker 2.37517 0 22 13.89 + 6 38 57.2 " 7.27482 0 14 55.56 +12 25 16.6 17 " 7.31545 0 14 51.87 +12 27 31.3 " 12.28941 0 10 13.72 +16 13 04.2 17.0 Lawrence 12.31233 0 10 12.38 +16 13 55.2 " C. S. Shoemaker, E. M. Shoemaker and D. H. Levy (Palomar). 0.46-m Schmidt telescope. Measurer C. S. Shoemaker. K. Lawrence, P. Rose and R. Bambery (Palomar). 0.46-m Schmidt telescope. Measurer J. Alu. Communicated by E. Helin. Preliminary orbital elements from the above observations by B. G. Marsden, Center for Astrophysics: T = 1991 Aug. 11.993 ET Peri. = 303.234 e = 0.53106 Node = 6.030 1950.0 q = 0.95736 AU Incl. = 14.048 a = 2.04153 AU n = 0.337886 P = 2.92 years 1991 ET R.A. (1950) Decl. Delta r V Oct. 11 0 11.21 +15 23.6 0.215 1.208 16.8 21 0 06.82 +20 01.7 31 0 08.11 +22 11.6 0.403 1.352 18.8 Nov. 10 0 13.41 +23 16.9 20 0 21.81 +23 55.2 0.634 1.503 20.1 MWC 560 Visual magnitude estimates (cf. IAUC} 5137): Jan. 7.97 UT, 9.7 (P. Schmeer, Bischmisheim, Germany); Mar. 3.98, 9.7 (Schmeer); Apr. 1.90, 9.6 (A. Pereira, Cabo da Roca, Portugal); May 13.88, 9.5 (Pereira); Sept. 17.21, 9.6 (Pereira); Oct. 5.18, 9.8 (Schmeer); 11.18, 9.9 (Schmeer); 16.18, 10.3 (Pereira); 18.16, 10.5 (Schmeer). 1991 October 24 Daniel W. E. Green