Central Bureau for Astronomical Telegrams
IAUC 2832: N Cyg 1975
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Read IAUC 2833
Circular No. 2832
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
W. M. Fawley, University of California at Berkeley, sends the
following re-reduced photometric observations (cf. IAUC 2830),
obtained with the Leuschner Observatory's 76-cm reflector. It is
possible that v on Aug. 30 is affected (by perhaps 0.02 magnitude)
by tube saturation. External errors in v and b-y are about 0.02.
1975 UT v b - y u - b v - b
Aug. 30.396 1.99 +0.393 +0.95 +0.36
30.521 1.95 +0.394 +1.01 +0.38
Sept. 2.185 3.95 +0.380 +0.16 +0.07
2.267 4.12 +0.349 +0.11 +0.06
2.318 4.18 +0.346 +0.11 +0.06
2.378 4.23 +0.344 +0.09 +0.05
G. de Vaucouleurs, Department of Astronomy, University of
Texas at Austin, provides the following V magnitudes, derived from
visual observations by J. Bryan, P. Young and himself: Aug. 30.1 UT,
2.06: (4); 30.2, 2.00 (6); 30.3, 1.96 (4); 31.05, 1.91 (4); 31.1,
1.94 (3); 31.25, 1.92 (2); Sept. 1.05, 2.07 (2); 1.1, 2.34 (2); 1.4,
2.88 (4); 2.05, 3.64 (2); 2.15, 3.63 (5); 2.4, 4.16 (4); 3.1, 4.50
(7); 3.25, 4.36 (2); 3.4, 4.57 (5); 4.1, 4.75 (6). The figures in
parentheses are the number of observations n, and the mean error is
then 0.05/n**0.5. From the exceptionally fast decay Dr. de Vaucouleurs
deduces that M_v = -9.5 at maximum, and allowing for absorption of
1.0 magnitude, he derives the nova's distance as about 1.6 kpc.
M. S. Burkhead, Department of Astronomy, Indiana University,
communicates the following preliminary photometric observations:
1975 UT V B - V U - B V - R V - I
Sept. 2.131 3.61 +0.4 -0.3 +1.4 +1.8
3.116 4.41 +0.4 -0.4 +1.8 +1.9
4.227 5.02 +0.4 -0.5 +2.1 +1.8
The following photometric observations were made by J. Krempec
at the Torun Observatory:
1975 UT V B - V 1975 UT V B - V
Aug. 30.8 2.70 Sept. 2.8 3.66 +0.94
31.8 2.58 3.8 4.08 +0.99
Sept. 1.8 3.41 +0.31
E. P. Ney and B. Hatfield, University of Minnesota, report the
following magnitude observations, made on Sept. 4.0 UT: V = 5.2, R
= 3.7, I = 3.2, 2.6 at 1.2 um, 2.6 at 1.6 um, 2.1 at 2.2 um, 1.0 at
3.5 um, 0.4 at 4.8 um, -0.3 at 8.5 um, -0.5 at 10.6 um, -1.1 at 12.5 um.
The following recent visual magnitude estimates have been
reported: Sept. 5.06 UT, 5.0 (W. Nissen, Arlington, Virginia); 5.06,
5.5 (L. Jacchia, Cambridge, Massachusetts); 5.07, 5.2 (D. di Cicco,
Waltham, Massachusetts); 5.07, 5.0 (C. Sherrod, North Little Rock,
Arkansas); 5.12, 4.8 (P. Maley, Houston, Texas); 6.02, 5.7 (Jacchia);
6.12, 4.9 (Maley); 7.08, 5.9 (Sherrod); 7.08, 5.2 (Maley); 8.07,
6.3 (Sherrod); 8.08, 6.1 (Jacchia); 9.06, 6.5 (Sherrod).
A. B. Hull, Flower and Cook Observatory, sends the following
polarization measures, obtained between Sept. 5.08 and 5.34 UT: at
3800 A, 1.26 percent in p.a. 52o, 1.20 percent in 52o, 1.02 percent
in 49o; at 4300 A, 1.31 percent in 47o, 1.38 percent in 47o; at
5400 A, 1.36 percent in 46o, 1.20 percent in 46o; at 6600 A, 1.04
percent in 50o, 1.04 percent in 51o.
A. Woszczyk, Torun Observatory, communicates: "A large number
of spectrograms were obtained between Aug. 29 and Sept. 4 by A.
Burnicki, W. Iwanowska, S. Krawczyk, A. Strobel and myself with the
Canadian Copernicus grating spectrograph attached to the Torun 90-cm
Schmidt-Cassegrain telescope. The dispersion is 28 A/mm and the
range 3560-5050 A. On Aug. 29.884 UT there was a strong continuum
and barely visible traces of very weak and flat Balmer absorption
lines blueshifted by about 1100 km/s. The mean expansion velocity
of this absorption feature grew rapidly, reaching 1300 km/s on Aug.
30.13, 1500 km/s on Aug. 30.9, 2100 km/s on Aug. 31.9, and it
stabilized at 2250 km/s between Sept. 1 and 4. The interstellar Ca II
lines were very fine and showed a velocity of about zero. Since
Aug. 30 very wide (total widths 3000 to 3400 km/s) emission lines
have appeared, and their intensities have been growing rapidly from
day to day. The following lines have been found: H-beta to H_10; Fe II
5018, 4924, 4296, 4233, 4179 A; a very large and complex emission
feature centered at 4570 A that is certainly due to Fe II 4630,
4584, 4549 and 4520 A. Fe II 4385 A is partially blended with H-gamma.
Beginning on Sept. 2 the emission lines showed a complex four-component
structure that became more and more accentuated."
J. B. Hutchings, Dominion Astrophysical Observatory, writes
that spectrograms obtained on Aug. 31 and Sept. 1 (dispersions 2.5
to 15 A/mm) show broad H and Fe II emissions (+/- 2500 km/s) and weak
absorptions at -2500 and -4000 km/s. Ca II had broad absorptions
at -2000 km/s. The low-velocity absorption weakened and increased
by ~ 200 km/s between the two nights.
E. Mannery, University of Washington, reports that observations
by R. Schommer on Sept. 4.2 UT (dispersion 60 A/mm) showed
broad Balmer emission lines, each with three narrow absorption
lines superimposed.
1975 September 9 (2832) Brian G. Marsden
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