Central Bureau for Astronomical Telegrams
IAUC 5463: N Cyg 1992; TIME ADJUSTMENT ON 1992 JUNE 30
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Circular No. 5463
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
NOVA CYGNI 1992
R. D. Gehrz, University of Minnesota, provides the following
infrared magnitudes, obtained by G. Lawrence, T. J. Jones, and himself
with the 0.8-m telescope and bolometer at the O'Brien Observatory
on Feb. 29.7 UT: J = 3.4, H = 3.2, K = 3.0, L = 2.3, M = 1.9,
N = 0.7. Narrower-band photometry, while confirming that the nova
is still probably in a free-free emission phase, suggests the possible
presence of an emission line (possibly neon or Humphreys alpha
hydrogen) near 12 microns: [7.8 microns] = 0.8, [8.7 microns] = 0.7,
[9.8 microns] = 0.9, [10.3 microns] = 1.1, [11.6 microns] = 0.3,
[12.5 microns] = -0.2, [18 microns] = 0.4.
A. Quirrenbach, Naval Research Laboratory, reports: "Preliminary
angular diameter measurements of N Cyg 1992 were made using the
20-m baseline of the Mark III Optical Interferometer operated on Mt.
Wilson by NRL. Observations at 800, 550, and 500 nm on Feb. 28 and
29 UT are consistent with a uniform-disk diameter of 0".0036 with
about 15 percent uncertainty; a Gaussian fit gives a half-power
diameter of about 0".0022. The diameter appears to be somewhat larger
at H-alpha."
Further photometry by B. Dintinjana and H. Mikuz (cf. IAUC
5459) using the University of Ljubljana 0.36-m Schmidt-Cassegrain
telescope (+ CCD) at the Crni vrh Observatory: Feb. 28.196 UT, V =
4.87 +/- 0.02, B-V = +0.34 +/- 0.02, V-R = +0.77 +/- 0.02 (comparison
star HR 7730). Mikuz also forwards the following additional
photometry from A. Dolzan, Litija, Slovenia (cf. IAUC 5460): Feb.
29.179, V = 4.92 +/- 0.02, B-V = +0.48 +/- 0.02, U-B = -0.49 +/-
0.04; Mar. 1.165, 5.30, +0.45, -0.53 (comparison star HR 7876).
Further selected visual magnitude estimates: Feb. 29.934 UT,
5.1 (B. H. Granslo, Blindern, Norway); Mar. 1.035, 5.3 (J. Pietz,
Erftstadt, Germany); 1.18, 5.3 (Mikuz); 1.45, 5.4 (G. W. Kronk,
Troy, IL); 2.11, 5.7 (R. Haver, Rome, Italy); 2.47, 6.1 (Kronk).
TIME ADJUSTMENT ON 1992 JUNE 30
Bulletin C3 of the International Earth Rotation Service announces
that a positive leap second will be introduced such that the
sequence of UTC second markers will be: 1992 June 30d23h59m59s,
30d23h59m60s, July 1d00h00m00s. From 1991 Jan. 1 to 1992 June 30,
the difference UTC-TAI = -26s; beginning 1992 July 1, UTC-TAI = -27s.
1992 March 2 (5463) Daniel W. E. Green
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