Central Bureau for Astronomical Telegrams
IAUC 2842: N Cyg 1975; 1974c; 1975d
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Read IAUC 2843
Circular No. 2842
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. Gieren and W. Seggewiss, Hoher List Observatory, write that
a spectrogram (dispersion 29 A/mm) obtained on Sept. 4.849 UT shows
that the Balmer lines were split into four emission peaks with four
corresponding violet-displaced absorption edges. This structure
was not present on Sept. 1.875 and earlier. On the other hand, the
four emissions and absorptions were again evident on Sept. 17.090,
with little change in the velocities. The velocities (km/s) were:
1975 UT E1 A1 E2 A2 E3 A3 E4 A4
Sept. 4 H-gamma + 739 + 427 + 210 - 169 - 469 - 762 -1051 -2538
17 H-gamma + 732 + 426 + 196 - 185 - 452 - 816 - 951 -3074
17 H-beta + 675 + 366 + 209 - 131 - 455 - 733 - 936 -3154
where the designations E1-E4 refer to the emission peaks, A1-A4 to
the absorption edges. The velocities could be measured quite
accurately, with the exception of the very broad and shallow
absorption feature A4. It should be especially noted that E1 and E2, as
well as A1, are shifted toward the red part of the spectrum.
P. Pesch, Warner and Swasey Observatory, communicates the
following remarks by P. Chen on image-tube spectrograms taken with the
91-cm telescope on Sept. 22 UT: "Spectrograms at a dispersion of
about 100 A/mm show that the nova is probably in the late Orion-early
nebular stage, very similar to McLaughlin's synthetic spectrum
of a nova about five magnitudes past maximum. The 4959,
5007 A complex has strengthened but not separated into distinct
components. The N III 4640 A, He II 4686 A complex is strong and
distinct, and H-beta has distinctly narrowed (present width ~ 50 A or
3000 km/s). The Fe II (multiplet 42) lines are barely discernible.
A higher dispersion (~ 24 A/mm) spectrogram of H-alpha shows four
distinct emission components."
A telegram received from G. R. Gilbert et al., University of
Arizona, on Sept. 30 reports: "The Steward Observatory television
scanner (and an image-tube configuration) shows O 8446 A (3p-3s)
emission to be of comparable strength to H-alpha. Fourier-transform
spectra by both Lunar and Planetary Laboratory and Steward Observatory
instruments show O 1.1287 um (3d-3p) to be comparable to P-beta and
O 1.3164 um (4s-3p) to be absent. These results show that the oxygen
lines are fed by a fluorescent mechanism from L-beta and that the
nova envelope has a large optical depth in H-alpha."
P. Tempesti, Collurania Observatory, writes that the 3-hour-period
variation in brightness (IAUC 2834) was confirmed by observations
on Sept. 11 and 14; on the latter date the amplitude of the
variation had decreased to 0.05 magnitude.
Further recent visual magnitude estimates: Sept. 17.9 UT, 7.7
(R. Lukas, Wilhelm Foerster Observatory); 19.07, 7.1 (C. Sherrod,
North Little Rock, Arkansas); 21.17, 7.3 (Sherrod); 23.09, 7.5
(T. R. Williams, Houston, Texas); 25.08, 7.3 (P. Maley, Houston,
Texas); 27.06, 7.4 (Maley); 28.04, 7.4 (Maley); 29.05, 7.4 (Maley).
COMET LOVAS (1974c)
A. C. Gilmore, Carter Observatory, provides the following precise
position, obtained from a 60-min exposure with the 41-cm Cassegrain
reflector. Measurer: P. M. Kilmartin. The comet was visible
as a diffuse spot 30" in diameter.
1975 UT R. A. (1950) Decl. m2
Aug. 25.41135 13 38 02.37 -69 47 00.3 14.8
COMET BRADFIELD (1975d)
The following parabolic elements, by B. G. Marsden, are from
43 observations Mar. 18 to June 18:
T = 1975 Apr. 4.5621 ET Peri. = 264.1136
Node = 157.2153 1950.0
q = 1.216677 AU Incl. = 55.2543
1975/76 ET R. A. (1950) Decl. Delta r m2
Oct. 15 11 25.97 + 6 31.l 3.749 2.941 19.6
25 11 37.56 + 6 36.7
Nov. 4 11 48.16 + 6 49.0 3.761 3.157 19.9
14 11 57.69 + 7 09.9
24 12 06.07 + 7 40.8 3.708 3.371 20.1
Dec. 4 12 13.19 + 8 23.3
14 12 18.91 + 9 18.6 3.608 3.581 20.3
24 12 23.11 +10 27.6
Jan. 3 12 25.65 +11 50.8 3.492 3.789 20.5
13 12 26.42 +13 27.4
23 12 25.36 +15 15.6 3.400 3.993 20.7
Feb. 2 12 22.47 +17 12.3
12 12 17.90 +19 12.6 3.378 4.195 20.9
22 12 11.92 +21 11.0
Mar. 3 12 04.92 +23 01.4 3.466 4.393 21.1
13 11 57.40 +24 38.5
23 11 49.93 +25 58.5 3.680 4.589 21.4
m2 = 12.0 + 5 log Delta + 10 log r
1975 October 1 (2842) Brian G. Marsden
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