Central Bureau for Astronomical Telegrams
IAUC 2928: 1975n
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Read IAUC 2929
Circular No. 2928
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
COMET WEST (1975n)
The following precise positions have been reported:
1976 UT R. A. (1950) Decl. m2 Observer
Jan. 1.45451 21 09 09.09 -35 03 28.0 Herald
3.39227 21 12 28.31 -34 46 22.5 10.5 Gilmore
9.52569 21 23 42.78 -33 47 45.3 Gans
9.53819 21 23 43.93 -33 47 34.3 "
Feb. 15.50417 22 59 36.36 -20 42 11.6 Candy
16.50417 23 02 28.53 -19 48 32.3 "
Mar. 6.53507 21 43 11.33 + 6 51 25.2 Giclas
10.17433 21 28 10.35 + 8 37 33.0 Milet
10.19701 21 28 05.64 + 8 38 03.4 "
10.53490 21 26 55.62 + 8 46 10.3 Giclas
11.17024 21 24 54.17 + 9 00 13.6 Milet
11.18054 21 24 52.22 + 9 00 27.5 "
13.53142 21 18 13.01 + 9 46 55.5 Giclas
15.52031 21 13 31.48 +10 20 21.0 "
D. Herald (Kambah, near Canberra). Correction to IAUC 2910.
A. C. Gilmore (Carter Observatory). Measurer: P. M. Kilmartin.
D. J. Gans and M. P. Candy (Perth Observatory, Bickley).
H. L. Giclas (Lowell Observatory). Measurer: M. L. Kantz.
B. Milet (Nice Observatory). Double tail > 15o in length.
J. C. Webber, L. E. Snyder, R. M. Crutcher and G. W. Swenson,
University of Illinois, report the detection, using the 37-m radio
telescope at the Vermilion River Observatory, of OH emission at
1667 MHz. The peak intensity of this line on Mar. 12, 13 and 14
was 0.15 Jy with full width at half height of 3.9 km/s.
C. Barth and G. Lawrence, University of Colorado, report that
ultraviolet observations (range 1250-1700 A) from a NASA Aerobee
rocket launched on Mar. 5.48 UT show the principal emissions to be
O I 1304 A, C I 1561 A and 1657 A and the fourth positive bands of CO.
The vibrational population of the CO bands was determined.
W. Weller, S. Jeffers and L. Danylewych, York University, report
that spectroscopic observations (ranges 3800-5000 A and 4400-6000
A, resolution 10 A) obtained on Mar. 11.40 UT using an intensifier
silicon vidicon spectrometer showed the band systems of C2
(Delta-nu = 0, +1 and -1) and CN (Delta-nu = 0). Preliminary analysis of C2
(Delta-nu = 0 and +1) gives a vibrational temperature of 5400 +/- 200 K and
a rotational temperature of 3200 +/- 100 K. The CN/C2 ratio appears
weaker than in comet 1973 XII at similar heliocentric distance.
Observations by J. P. Swings, European Southern Observatory,
on Mar. 12.41 UT describe strong CN (0,0), CH, C2 (1,0) and C2
(0,1) emission and medium-strength C3, CN (0,1) and C2 (2,0) on a
weak to very weak continuum. C. Fehrenbach, Observatoire de Haute
Provence, also mentions the well developed emissions due to C2, CN
and CH, with C3 somewhat less intense; continuous emission was also
detected from the nucleus.
R. E. McCrosky and G. Schwartz, Harvard College Observatory,
report that observations (5200-7000 A) on Mar. 18.4 UT using the
echelle spectrograph and an image tube on the 155-cm reflector
confirm the presence of H-alpha emission (cf. IAUC 2927) shifted ~ 20 km/s
blueward of solar-absorption H-alpha. Na I was still very strong.
Reporting on the tail spectrum, E. M. Leibowitz, M.
Rosenkrantz and A. Levite, Wise Observatory, mention the 6-0, 7-0,
8-0 and 9-0 bands of H2O+, extending about 7' from the head on Mar.
11.1 UT. Traces of the 10-0 system were possibly present, but the
5-0 bands were missing.
Photographs obtained by T. L. Rokoske, Boone, North Carolina;
J. Young, Wrightwood, California; J. A. Farrell, Los Alamos, New
Mexico; and D. di Cicco, Waltham, Massachusetts, show that the
synchronic bands (cf. IAUC 2924) were present as early as Mar. 4.4 UT
but that by Mar. 9.5 they had become very weak. J. Bortle, Brooks
Observatory, reports further visual observations of tail structure:
Mar. 12.41 UT, 11o long in p.a. 293o (gas), 12o.5 in 310o and 26o.5
in 320o (dust); 14.40, 9o in 288o (gas), streamer in 306o and 10o
in 315o (dust); 18.40, 5o.5 in 297o (in bright moonlight).
E. P. Ney and K. M. Merrill, O'Brien Observatory, University
of Minnesota, report the following visual and infrared magnitudes,
obtained on Mar. 10.8 UT with a diaphragm of 20": V = +4.8, R =
+4.4, I = +4.1; 1.2 um, +3.4; 1.6 um, +3.0; 2.2 um, + 2.4; 3.5 um, -0.7;
4.8 um, -2.7; 8.5 um, -5.2; 10.6 um, -6.1; 12.5 um, -6.2; 18 um, -6.8.
J. S. Neff, D. A. Ketelsen and V. V. Smith, University of Iowa,
report that drift scans on Mar. 11.5 UT show that the intensity in
a band centered on the C2 5100 A emission was about twice that of
the continuum in a similar band near 5250 A.
Further selected total visual magnitude estimates: Mar. 6.46
UT, 1.4 (C. S. Morris, West Lafayette, Indiana, 8 x 52 elbow telescope);
7.51, 1.3 (A. Hale, Alamogordo, New Mexico, naked eye);
9.47, 2.0 (P. Maley, Houston, Texas, 7 x 35 binoculars); 10.46, 1.9
(Maley); 12.41, 1.9 (Bortle, 10 x 50 binoculars); 12.50, 2.3 (M. J.
Mayo, Mount Wilson, California, 7 x 35 binoculars); 13.45, 1.6
(W. I. Nissen, Arlington, Virginia, naked eye); 13.52, 2.4 (Mayo);
14.40, 2.1 (Bortle); 14.44, 2.5 (K. Simmons, Jacksonville, Florida,
naked eye); 15.56, 2.7 (Mayo and J. Truxton, Agoura, California);
17.4, 3.2 (Maley); 18.40, 3.1 (Bortle).
1976 March 19 (2928) Brian G. Marsden
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