THE ASTRONOMER Electronic Circular No 574 1991 Oct 25 18.00UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP, England. Telephone: (0256)471074 Int:+44256471074 Telex: 9312111261 Answerback: TA G JANET BOXES: GMH at UK.AC.CAM.ASTRONOMY.STARLINK or GUYH at UK.AC.SUSSEX.CLUSTER TELECOM GOLD: 10074:MIK2885 PRESTEL 256471074 ------------------------------------------------------------------- TAV 1831+19 Further to the report on E565, Martin Mobberley, Cockfield, has submitted prints of an exposure taken on 1991 Oct 6 (19.08-19.23UT) using the 0.36-m reflector and hypered Kodak 2415 film. The Editor has derived an approximate extended sequence to 15.4 and paper copies are available on request of a new (c) chart. In the position of the variable is a pair separated by approximately 7" and aligned north-south. According to the preliminary extended sequence (TA 911025) the editor estimates the northern component at 12.2 and the southern star at 12.6. Further prime focus photographs are now needed to establish which component is the variable. 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." IAUC 5372 Paul Roche, Astronomy Group, Southampton has appealed for observations of this star which is on the binocular programme of the BAAVSS. He comments that the disk is returning on a very short timescale, as they have spectra from a month earlier which show absorption only. It is possible that a visual outburst may occur. Latest visual estimates place the star around 6.5v. Please e-mail results weekly until further notice. EF PEGASI (cf E573) 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 best-fit superhump period for these data is 0.091 +/- 0.01 day, in agreement with that found by Kato and Takata (E573). 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. IAUC 5372 Guy M Hurst