FIR sources were reliably detected at the positions of 24 out of the
considered 367 SCGGs. Data for the detected FIR sources is presented
in Table 1. Column 1 lists the Shakhbazian designation of the group
in the first row. In the second row of Col. 1 the identification number
of the galaxy (as labeled on the original SCGG finding charts) which is
within the 60 m IRAS beam and is suspected to be the dominant FIR
emitter, based on proximity to the IRAS source position and optical
brightness, is given.
Column 2 gives the diameter of the group in arcminutes. In Cols. 3 and 4
the right ascension and declination (J2000.0) of the IRAS source are
listed in the first row; the coordinates of the suspected dominant
FIR-emitting galaxy are listed below. In Cols. 5, 6, and 7 the flux
densities at 25
m, 60
m and 100
m are presented
together with their SNR (in parentheses). The fluxes determined by
the SCANPI method in some cases differ from that given in the IRAS
catalogs. This is generally due to underestimates of flux densities
in the IRAS catalogs for sources which are slightly resolved by the
IRAS beam.
Isophotes of the detected FIR sources at 60 m overlaid on
POSS
E (red) images of the groups are presented in Fig. 2. To
produce these plots, the IRAS FRESCO/HIRES images in cartesian
(nearly orthographic) B1950 coordinates were contoured into "vector
files'' in the B1950 system. Then the AGRA package developed at IPAC
was used to project the contour vectors point-by point into the J2000
"plate'' projection system of the DSS images. The reprojected contours
were then overlayed on a grayscale of the J2000 DSS image, and a
coordinate grid and scale were added using the IPAC Skyview image
analysis package.
As mentioned above, the angular sizes of SCGGs are very small and in
many cases they are of the order of 1-2 arcmin. This is smaller
than the angular resolution (beam size) of IRAS at 60 m, which
is nominally
FWHM. Hence usually it is
impossible to determine which galaxy of the group might be the
dominant FIR emitter. It is likely, as suggested by Sulentic & De
Mello Rabaça (1993) for HCGs, that more than one galaxy in the
group contributes to the total observed FIR emission. In some cases,
such as Shkh 22, 176 and 243, the FIR source is extended, providing
evidence that more than one galaxy contributes to the FIR emission.
The second IRAS source within the boundaries of Shkh 22 may be associated
with galaxies No. 2 and/or 3. Thus, it is possible that in some cases IRAS
has detected the integral FIR emission of a few galaxies in the groups.
Several IRAS sources were detected in the vicinity of SCGGs, but with
positions and uncertainty ellipses centered outside the group boundaries.
Most of these have been identified with galaxies or stars that are merely
projected near the corresponding SCGGs. For 10 remaining SCGGs, IRAS
sources were found close to the groups, but SCGG galaxy members could
not be confidently identified as the FIR source for various reasons.
The 10 SCGGs with possible IRAS detections are presented in Table 2,
where the columns contain the same parameters as the first row in
Table 1. Since the IRAS detector in-scan and cross-scan widths at
60 m were
and
arcmin respectively, it is
possible that these IRAS sources may be associated with members of the
galaxy groups. However, confusion with foreground Galactic cirrus, lack
of FSC or FSCR counterparts, or location near the edge of the IRAS beam
make the identification very uncertain. The remarks following Table 2
indicate why each IRAS source has an uncertain association with the
corresponding galaxy group. Figure 3 presents IRAS isophotes overlayed
on visual DSS fields for the sources in Table 2.
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