Central Bureau for Astronomical Telegrams
IAUC 2828: N Cyg 1975; NOTICE TO SUBSCRIBERS
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Circular No. 2828
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK
Western Union: RAPID SATELLITE CAMBMASS
NOVA CYGNI 1975
A cablegram from the University of Helsinki Observatory gives
the following linear polarization measurements, obtained by Piirola
on Aug. 30.9 UT: in V, 1.16 percent in p.a. 48o.4; in B, 1.12 percent
in 48o.0; in U, 1.10 percent in 48o.5. The magnitudes were V =
1.88, B-V = +0.62, U-B = -0.19
Boudewijn and Baud, Leiden Observatory, report the following
broad band polarization measurements, obtained on Aug. 31.00 UT:
at 5200 A, 1.18 percent; at 7800 A, 1.06 percent. The equatorial
position angle was 47o.8. The full width of each band was 1000 A.
P. W. Sanford, P. A. Charles and K. O. Mason, Mullard Space
Sciences Laboratory, report that no significant signal down to an
upper limit of 10**-10 erg cm**-2 s**-1 was detected in the energy range
2.5 to 7.5 keV during a 3-hr interval beginning on Sept. 1.50 UT.
The following selected visual magnitude estimates have been
reported: Aug. 31.24 UT, 1.9 (J. Ashbrook, Weston, Massachusetts);
31.37, 2.2 (L. Jacchia, Cambridge, Massachusetts); 31.74, 1.9 (D. P.
Elias, Athens Observatory); Sept. 1.02, 2.4 (Jacchia); 1.36, 2.3 (H.
Povenmire, Indian Harbour Beach, Florida); 2.03, 3.5 (D. di Cicco,
Waltham, Massachusetts).
L. Jacchia, Center for Astrophysics, remarks that in spite of
the rise of at least 19 magnitudes to maximum (IAUC 2826), the
spectrum of this object (IAUC 2827) is more typical of a nova than
of a supernova. He compares Nova Cyg 1975 with Nova CP Pup 1942,
which rose at least 16.5 magnitudes to maximum, and suggests that
both objects might be virgin novae, erupting for the first time.
CP Pup exhibited a very rapid initial decline and seems to have
settled down only 14 magnitudes fainter than maximum.
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1975 September 2 (2828) Brian G. Marsden
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