Central Bureau for Astronomical Telegrams
IAUC 4990: MWC 560; GINGA Obs OF NGC 5548
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Read IAUC 4991
Circular No. 4990
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
MWC 560
S. Mochnacki and J. Thomson, David Dunlap Observatory,
communicate: "We observed MWC 560 on the six consecutive nights during
Mar. 24-29 UT in the blue, using the fiber-fed Photon Counting
Spectrometer with photon time tagging on the 1.9-m telescope. The
integrated spectrum for Mar. 24, covering 400-500 nm, shows Balmer
emission with a strong decrement and possibly shallow Balmer
absorption blueward of H-beta. Other absorption features are shallow.
The other five nights, covering 470-495 nm at a resolution of about
0.05 nm, show a shallow wedge of absorption deepest just shortward
of the H-beta emission and extending some 10 nm blueward, deepening
on successive nights. On the night of Mar. 28 a stronger absorption
appears, centered on 482.5 nm and with FWHM of about 900 km/s. On
Mar. 29, there appears a very deep absorption feature at 481.4 nm,
with FWHM about 500 km/s, and another broader, somewhat shallower
feature at 483.5 nm. On Mar. 29, the previously seen shallow
absorption stops abruptly at 480.8 nm, on the blue edge of the deep
absorption feature. The higher resolution integrations show sharp
emission lines typical of symbiotic stars. The strongest (apart
from H-beta) is Fe II (42) at 492.39 nm, and other species include
Cr II, Ti II, Fe II, He I, and Fe VII. Several emission lines lie
within the strong absorption features observed on Mar. 28 and 29,
and therefore are not absorbed by the variable strong blue-shifted
H-beta. The weak emission lines have a radial velocity of about
+40 km/s, similar to the strong H-beta emission, which also has a
broad base. Poor weather has prevented subsequent observations."
GINGA OBSERVATIONS OF NGC 5548
F. Makino and Ginga Team telex: "The x-ray astronomy satellite
Ginga will observe the Seyfert galaxy NGC 5548 for six days from May
25 to 30 and monitor the galaxy every seven days from May 30 to July
10. Simultaneous or quasi-simultaneous coverage in ultraviolet,
optical, and infrared is strongly encouraged. For exact start and end
times of the observations, contact F. Makino, Institute of Space and
Astronautical Science, 3-1-1, Yoshinodai, Sagamihara 229, Japan
(telephone 81-427-51-3911, extension 2621; FAX 81-427-59-4253; telex
34757 ISASTRO)."
1990 April 9 (4990) Daniel W. E. Green
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