Central Bureau for Astronomical Telegrams
IAUC 2704: 1974e; BINARY PULSAR; LUNAR Occn OF THE CRAB NEBULA IN HIGH-ENERGY X-RAYS; P/HONDA-MRKOS-PAJDUSAKOVA; SCO X-1 = V818 SCO
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Read IAUC 2705
Circular No. 2704
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 CESCO (1974e)
Dr. C. U. Cesco, Observatorio Astronomico Felix Aguilar,
communicates the following precise positions, obtained by M. R. Cesco
and himself with the 51-cm double astrograph at El Leoncito. In
September the images were diffuse, but measurement was satisfactory.
1974 UT R. A. (1950) Decl.
Aug. 15.04868 16 49 32.78 -31 32 27.6
15.06322 16 49 29.97 -31 32 15.9
16.01617 16 46 38.82 -31 19 53.3
16.02933 16 46 36.55 -31 19 42.7
21.00806 16 34 23.22 -30 21 08.3
21.02260 16 34 21.36 -30 21 00.0
Sept.17.03135 16 10 38.51 -27 29 32.1
18.01787 16 10 30.09 -27 26 31.5
The following improved orbital elements, by B. G. Marsden,
satisfy the available accurate positions within 2". The departure
from parabolic motion seems to be significant.
T = 1974 May 13.1019 ET Peri. = 176.8462
e = 0.981944 Node = 165.0476 1950.0
q = 1.373526 AU Incl. = 173.1652
BINARY PULSAR
J. H. Taylor and R. A. Hulse, University of Massachusetts,
report: "In the course of a systematic survey for new pulsars carried
out at the Arecibo Observatory, we have discovered a remarkable
object with a pulsation period of about 0s.059. Periodic changes in
the pulsation rate indicate that the pulsar is one member of a
binary system, and a velocity curve for this 'spectroscopic binary'
has been obtained. Measured parameters are: R.A. = 19h13m14s +/- 20s,
Decl. = +16o00' +/- 5' (equinox 1950.0); l = 49o.9, b = +2o.1; pulsation
period, minimum 58.967 ms, maximum 59.045 ms; dispersion measure,
167 +/- 5 pc cm**-3; average flux density, 0.005 Jy; period of binary
orbit, 27 907 +/- 30 s (0.3230 day); radial velocity semiamplitude,
198 km s**-1; eccentricity, 0.61; projected semimajor axis of orbit,
690 000 km; mass function, 0.13 Msol."
LUNAR OCCULTATION OF THE CRAB NEBULA IN HIGH-ENERGY X-RAYS
G. Ricker, A. Scheepmaker, J. Ballintine, J. Doty, P. Downey,
S. Ryckman and W. Lewin report preliminary results of a high-energy
(20-150 keV) observation of the lunar occultation of the Crab
Nebula on Aug. 13. The observations were made from North Battleford,
Sask., using a 700 cm**2 balloon-borne telescope. The p.a. of
the pulsar NP 0532 at immersion was 130o, while that at emersion
was 244o. Eighty percent of the total x-ray flux from the Crab
Nebula (including the pulsar) was observed to come from a region
30" +/- 10" in width for the immersion and 60" +/- 10" in width for the
emersion. In both cases the emitting region appeared to be centered
on NP 0532 to an accuracy of +/- 10". Over the 20-150 keV range
there appeared to be little, if any, variation in the angular size
with energy. Observers planning measurements of future occultations
and requiring further details are encouraged to contact Dr.
Ricker or Dr. Scheepmaker at the Center for Space Research,
Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.
(telephone (617) 253-7532]; or Dr. Lewin at the Cosmic Ray Working
Group, Leiden, The Netherlands.
PERIODIC COMET HONDA-MRKOS-PAJDUSAKOVA
Mr. J. Bortle, Brooks Observatory, writes that observations by
him in 1969 and by M. Beyer in 1954 yield the following formula for
the total visual magnitude: m1 = 13.43 + 5 log Delta + 19.11 log r.
This formula should be satisfactory when r < ~1.0 AU and results in
the following predicted values for the current return (cf. IAUC
2697)
1974 ET m1 1974 ET m1 1975 ET m1 1975 ET m1
Nov. 19 13.4 Dec. 19 8.8 Jan. 8 7.7 Feb. 7 10.0
29 12.0 29 7.9 18 8.2 17 11.4
Dec. 9 10.4 28 8.9
SCO X-1 = V818 SCO
E. W. Gottlieb, E. L. Wright and W. Liller, Center for
Astrophysics, Harvard and Smithsonian Observatories, report that the
analysis of 1068 magnitudes, obtained from Harvard blue plates
taken between 1889 and 1974, suggests that the period is 0.787313 +/-
0.000001 day, in agreement with postdiscovery photometry. The
sinusoidal light curve has a full amplitude of 0.22 +/- 0.03 magnitude.
1974 October 4 (2704) Brian G. Marsden
Read IAUC 2705
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