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IX/4 Fourth UHURU Catalogue (4U) (Forman+ 1978)
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4u.dat
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Fourth UHURU Catalogue
Forman W., Jones C., Cominsky L., Julien P., Murray S., Peters G.,
Tananbaum H., Giacconni R.
<Astrophys. J. Suppl. Ser. 38, 357 (1978)>
=1978ApJS...38..357F
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ADC_Keywords: X-ray sources
Mission_Name: SAS-1
Keywords: X-rays: sources
Abstract:
The Fourth Uhuru (4U) Catalog lists 339 X-ray sources that were
observed with the Uhuru (SAS A) X-ray observatory. It contains
positional information in the form of 90% confidence level error
boxes, 2-6keV intensities, possible optical and radio counterparts,
and alternative names for sources observed in earlier compilations.
The major classes of identified objects include binary stellar
systems, supernova remnants, Seyfert galaxies, clusters of galaxies,
and possibly the new class of superclusters of galaxies.
The Uhuru satellite was a scanning X-ray instrument with a narrow (1
by 10 degree FWFM) and a wide (10 by 10 degree FWFM) collimator (cf.
Giacconi et al. 1971ApJ...165L..27G). Typically, the scan rate was
0.5degree/second, with the spin axis in one position for roughly one
day. During the interval for which the spin axis was fixed, repeated
scans were made of the same 10 by 360 degrees band of the sky. For
this catalog, the individual scans were superposed using aspect data
from an orthogonally mounted triad of magnetometers and a Sun sensor
onboard the spacecraft, supplemented by observations of well-located
X-ray sources. The observations employed in producing this catalog
were obtained over a total of 429 days between 1970 December 12 and
1973 March 18, apart from a gap between 1972 July and December when
the spacecraft's transmitter was operating improperly.
Description:
Positions and intensities are presented for 339 X-ray sources observed
by the Uhuru (SAS-1) X-ray satellite observatory. Correspondances with
the sources in the 3U and 2A catalogs are given. Optical and radio
counterparts are suggested based on positional coincidence
This online catalog was created by the HEASARC in March 2003 based on
a table obtained originally from the ADC website
(ftp://legacy.gsfc.nasa.gov/heasarc/dbase/misc_files/uhuru4/4u.dat),
which was modified by the HEASARC to include some parameters that were
in the published catalog (Table 1 in the reference) but were not in
the ADC table. The HEASARC made a small number of other changes and
corrections to the table which are listed in the
HEASARC_Implementation section of this help. Notice that the ADC table
itself differs in a number of respects from the published Table 1,
e.g., the comments are sometimes abbreviated and/or different, some of
the names are slightly different (usually by one digit in the RA
minutes part), and three of the entries have differing names and
positions.