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IAUC 2795: N Sct 1975; ERUPTIVE Var IN Aql; HDE 226868; V436 Cen; P/ENCKE

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IAUC number

                                                  Circular No. 2795
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.

     The following prediscovery observations have been reported:

     1975 UT       mpv  Observer      1975 UT       mpv  Observer
     May  10.3    ~6.1  Mallama       May  19.697  ~7.8  Hishikura
          17.690  ~7.8  Hishikura     June  1.618   7.7  Tsuchiya
          18.692   8.4  Mochizuki          10.661   7.3    "

A. D. Mallama (University of Toledo) on plate taken by D. Wereb
   (Perkins Observatory).  IIa-F emulsion.  Provisional reduction.
T. Hishikura (Yokosuka, Kanagawa) and K. Tsuchiya (Asahigawa, Hokkaido).
   From Hoshino Hiroba Circ. Nos. 2132 and 2133.
H. Mochizuki (Konyama, Fukushima).  Tri-X film.  Measurer: M.
   Koishikawa (Sendai Astronomical Observatory).

     The following selected visual magnitude estimates have been
reported: June 19.12 UT, 9.5 (J. Bortle, Brooks Observatory); 20.23,
9.0 (M. Mattei, Littleton, Massachusetts); 21.05, 8.2 (K. Locher,
Grut-Wetzikon, Switzerland; main comparison star USNO 16115, V =
9.55); 21.12, 8.4 (Bortle); 22.14, 8.2 (Bortle); 22.21, 8.4
(Mattei); 23.0, 8.1 (I. D. Howarth, Portsmouth, England); 24.05,
8.1 (Locher); 24.96, 7.9 (U. Surawski and U. Hopp, Wilhelm Foerster
Observatory); 25.30, 7.7 (C. Sherrod, North Little Rock, Arkansas);
25.94, 8.0 (Hopp); 25.96, 8.1 (Locher); 26.31, 8.6 (Sherrod); 26.97,
8.7 (Surawski); 27.34, 9.0 (Sherrod); 28.13, 9.0 (Mattei); 29.15,
8.7 (K. Simmons, Switzerland, Florida); 29.32, 9.1 (Sherrod); 29.36,
9.7 (E. Mayer, Barberton, Ohio); July 1.12, 8.9 (D. di Cicco, Waltham,
Massachusetts); 1.14, 8.8 (Simmons); 1.32, 9.2 (Sherrod);
1.33, 9.6 (Mayer); 2.14, 9.0 (di Cicco); 3.14, 9.7 (di Cicco); 4.33,
9.0 (Sherrod); 5.15, 9.6 (Mattei); 5.25, 9.0 (Sherrod).

     J. Gallagher, University of Minnesota, reports: "Image-tube
spectrograms of the nova were obtained on June 25.3 and 28.3 UT
with the 76-cm reflector at the O'Brien Observatory.  The June 25
blue spectrum has a strong continuum and Balmer emission lines with
P-Cyg profiles indicating a velocity of more than 1400 km/s; an
infrared spectrum shows emission from O I 7772-7775 A and 8446 A and
N I 8216-8223 A.  The June 28 spectra have a weaker continuum, and
the broad, high-excitation emission blend near 4640 A appears
strongly; H-alpha is in strong emission with the velocity halfwidth of
1600 km/s, and weak absorption may be present to velocity about
2500 km/s; other strong infrared emission lines include [O II]
7319 and 7331 A; O I 7772-7775 A and 8446 A; N I 8216 A is considerably
weaker than on June 25.  Assisting with the observations were M.
Gallagher, R. Hubbard and J. Warner."

     The following magnitude estimates have been reported of the
nova or other eruptive variable described on IAUC 2788: June 14.02
UT, mv = 13.0 +/- 0.2 (G. M. Hurst, Northampton, England); 21.32,
mpg = 12.7 (C. Y. Shao, Harvard College Observatory); July 1.23,
mpg = 13.6 (Shao); 1.26, mpv = 13.0 +/- 0.5 (C. Scovil, Stamford
Museum); 2.3, mv = 13 (Scovil).  Mr. Shao adds that examination of
the Palomar Sky Survey prints shows no stars brighter than
photographic magnitude 19 at the position of the object.

HDE 226868
     B. Campbell, David Dunlap Observatory, writes: "Spectrum scans
(8-16 A resolution) in the red region of HDE 226868 (the optical
counterpart of Cyg X-1) indicate that the emission at H-alpha is weaker
than that reported at similar phases prior to the recent x-ray
transition (IAUC 2778).  On May 9.24 UT (photometric phase phi =
0.098) only weak absorption was present, while on May 28.32 (phi =
0.506) neither absorption nor emission greater than 3 percent of
the continuum intensity was observed.  On June 11.29 (phi = 0.001,
superior conjunction) H-alpha was in emission to 5 percent of the continuum.
The equivalent width was 390 +/- 70 mA and the total line
width 13 A, substantially less than previously reported."

     B. Warner, Department of Astronomy, University of Cape Town,
writes: "Observations of the dwarf nova V436 Cen during outburst on
June 10 and 11 show it to have a recurrent hump in its light curve
similar to that seen in VW Hyi at supermaximum (Warner 1975,
Monthly Notices Roy. Astron. Soc. 170, 219).  The period is close
to 89 min.  In VW Hyi the period of the 'superhump' is some 3 percent
longer than the true orbital period; therefore, if the recent
outburst of V436 Cen was a supermaximum, the true orbital period of
this star may also be somewhat less than 89 min, giving it a period
close to that of WZ Sge."

     Mr. A. C. Gilmore, Carter Observatory, sends the following
remeasurements, by Pamela M. Kilmartin, of observations reported
previously (cf. IAUC 2693, 2751).  The observation by R. R. D. Austin
was made at Mount John University Observatory.

     1974 UT             R. A. (1950) Decl.        Observer
     May  30.71926     2 02 27.86   -13 04 47.0    Austin
     July 20.43331    20 08 14.87   -40 53 00.2    Gilmore

1975 July 7                    (2795)              Brian G. Marsden

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