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IAUC 3201: N Ser 1978; 4U 1538-52; X Per

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                                                  Circular No. 3201
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK     Telex: 921428
Telephone: (617) 864-5758

     M. K. V. Bappu, Indian Institute of Astrophysics, reports that
image-tube spectrograms obtained by T. P. Prabhu with the Kavalur
100-cm telescope during Mar. 10.92-11.01 UT (dispersion 165 A/mm,
range 4200-8700 A) and during Mar. 11.95-11.97 UT (86 A/mm, 7200-8700 A)
exhibit a principal spectrum.  Emission lines of H, Na D, Ca
II (multiplet 2), Fe II (multiplets 42 and 49), O I 7772 and 8446 A
are very strong.  [O I] 6300 and 6363 A, N II 5755 A, Fe II (multiplets
27, 37, 38, 40, 73 and 74), O I 8228 A, Si II 6347 and 6371 A
and Mg II 4481 A are moderate.  Typical velocity widths are 1600
km/s.  H-alpha has a total width of 2650 km/s at zero intensity; the
mean absorption velocity is -1240 +/- 60 (p.e.) km/s.  On Mar. 19.96
UT the H-alpha profile (dispersion 25 A/mm) shows a sharp edge at -510

4U 1538-52
     A. Cowley, D. Crampton and J. B. Hutchings, Dominion Astrophysical
Observatory, report that spectrograms of candidate star 12
(IAUC 3184, 3197) obtained at Cerro Tololo Interamerican Observatory
show radial-velocity variations (K ~ 25 km/s) in the 3.73-day
x-ray period in antiphase with the x-ray pulsations (IAUC 3078).
This confirms the star as the optical candidate for the source.

     P. Bernacca and A. Bianchini, Asiago Astrophysical Observatory
communicate: "Photoelectric observations were perfomed on X Per
from January to March using a two-channel photon-counting photometer
with 1-second integration time in the U band.  On Mar. 9 and 10
four attenuation features of duration 10 to 30 seconds and depth
0.06 to 0.2 magnitude (6 to 18 percent) were observed.  Analysis of
the comparison star, which is much fainter than X Per, indicates
that the probability of reduced sky transparency being responsible
for these features is not larger than 0.3 percent for three of them
and not larger than 0.01 percent for the deepest one.  These dips
are similar to those observed by Campisi et al. (1976, Monthly Notices
Roy. Astron. Soc. 176, 225) in U light and by Canizares et al.
(preprint) in 4686 A light using a one-channel photometer."

1978 March 24                  (3201)              Brian G. Marsden

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