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IAUC 3509: 1978 P 1; OH 351.78-0.54

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                                                  Circular No. 3509
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM     Telephone 617-864-5758

1978 P 1
     D. Bonneau, Centre d'Etudes et de Recherches Geodynamiques et
Astronomiques, Caussols; and R. Foy, Observatoire de Paris, telex:
"We have obtained resolution of 1978 P 1 from Pluto with the 3.60-m
Canada-France-Hawaii telescope on Mauna Kea using speckle
interferometry.  On June 20 at 6h30m UT we observed 1978 P 1 at position
angle theta = 167o +/- 1o.5 and separation rho = 0".740 +/- 0".020, and on June
23 at 7h15m we found theta = 349o.5 +/- 1o.0 and rho = 0".850 +/- 0".010, with a
visual magnitude difference between the two objects of 1.6 +/- 0.2
(the visual mean opposition magnitudes for Pluto and 1978 P 1,
respectively, being 15.3 and 16.9).  From these observations we have
derived the linear diameters of Pluto and 1978 P 1, respectively,
as 4000 km and 2000 km, the radius of the orbit as 1".02, the
albedos as 0.20, the total mass of the system as 1/300 Mearth, and the
densities as 0.5 g cm**-3."

OH 351.78-0.54
     J. L. Caswell and R. F. Haynes, Division of Radiophysics,
Commonwealth Scientific and Industrial Research Organization, Sydney,
report: "OH 351.78-0.54 (R.A. = l7h23m20s.9, Decl. = -36o06'46", equinox
1950.0), which was first detected at Parkes in 1977 Sept., is now
the brightest OH maser in the sky.  Observations with 2-kHz
resolution on 1980 Aug. 26 showed that the most intense feature on the
l665-MHz transition (at l.s.r. velocity -2 km/s) was six times
stronger than in 1977, the peak flux density being 500 Jy in left-hand
circular polarization (and 170 Jy in right-hand polarization).
Of the 30 strongest features seen at 1665 or 1667 MHz, 19 had
increased and 11 decreased in intensity over the 3-year period.  The
maser is embedded in an extensive OH cloud which gives rise to
absorption on the l720-MHz transition and emission at 1612 MHz.  A
continuum source in this direction with flux density at 5 GHZ of
0.3 Jy (Haynes, Caswell and Simons 1979, Aust. J. Phys. Astrophys.
Suppl. No. 48) is probably a weak HII region.  The uncommonly large
intensity changes in the maser emission and the absence of strong
HII emission suggest that the region may be still in the early
stages of star formation, and monitoring of the OH intensity, together
with a search of H20 maser emission and any infrared protostar
counterpart, are desirable."

1980 September 8               (3509)              Daniel W. E. Green

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