Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.atnf.csiro.au/research/multibeam/papers/juraszek.ps.gz Äàòà èçìåíåíèÿ: Tue Jan 18 03:21:50 2000 Äàòà èíäåêñèðîâàíèÿ: Sun Dec 23 05:33:58 2007 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: m 43

Version 10/12/99 - Submitted to AJ
A Blind H I Survey for Galaxies in the Zone of Avoidance, 308 ô  `  332 ô .
S. Juraszek, 1;2 L. Staveley-Smith, 2 R.C. Kraan-Korteweg, 4 A.J. Green, 1 R.D. Ekers, 2 R.F.
Haynes, 2 P.A. Henning, 3 M.J. Kesteven, 2 B. Koribalski, 2 R.M. Price, 3 E.M. Sadler, 1 A. Schroder 5
ABSTRACT
We report on a blind neutral hydrogen survey for galaxies using the 21 cm
multibeam receiver on the Parkes 64 m telescope. The surveyed region covers jbj  5 ô
in the Zone of Avoidance (ZOA) from Galactic longitude 308 ô to 332 ô . The survey
represents the rst phase of a blind H I survey covering the southern ZOA (l = 212 ô
to 36 ô ). We have detected H I in 42 galaxies above a 3 limit of 60 mJy. The galaxies
detected in this survey have velocities out to 6000 km s 1 and H I masses in the range
4  10 7 to 3  10 10 M (h 2
75 ). Only 8 of the 42 galaxies have velocities previously
measured. A further 9 galaxies appear to have optical counterparts in the catalog of
Woudt (1998). In total, 16 of the galaxies appear to be associated with IRAS sources,
although only 3 of these are without optical counterparts. The estimated median
extinction for the 20 galaxies with optical or IR counterparts is AB = 3:8 mag. For
the 22 galaxies with no counterparts, the estimated median extinction is AB = 5:6
mag. The distribution of galaxies is suggestive of a connection between the Centaurus
supercluster above the Galactic Plane and the Pavo-Indus supercluster beneath the
Plane. No previously hidden concentrations of galaxies were found.
Subject headings: surveys { galaxies: distances and redshifts { galaxies: fundamental
parameters { radio lines: galaxies
1. Introduction
Historically, astronomers have not studied large-scale structures close to the Galactic Plane
due to the obscuring eects of dust and high stellar density. The size of this Zone of Avoidance
1 School of Physics, University of Sydney, NSW 2006, Australia
2 Australia Telescope National Facility, CSIRO, P.O. Box 76, Epping, NSW 2121, Australia
3 Institute for Astrophysics, University of New Mexico, 800 Yale Blvd, NE, Albuquerque, NM 87131, USA
4 Departemento de Astronomia, Universidad de Guanajuato, Apartado Postal 144, Guanajuato, Gto 36000, Mexico
5 Observatoire de la C^ote d'Azur, B.P.4229, 06304 Nice Cedex 4, France

{ 2 {
(ZOA) varies with Galactic longitude and observing wavelength. One estimate of its extent (Lahav
1994) suggests that 20% of the sky in the optical and 10% in the infrared are obscured. As a
result of this obscuration, very little systematic and uniform data on galaxy distributions exist for
jbj < 10 ô . A complete picture of the galaxy distribution is essential for studies of nearby large-scale
structure and its eect on the motion of the Local Group of galaxies. For example, Kolatt, Dekel
& Lahav (1995) nd that the mass distribution for ZOA galaxies out to 6000 km s 1 strongly
aects the direction of the predicted gravitational acceleration at the position of the Local Group.
Marinoni et al. (1998) also point out that their predicted barycenter for the massive Shapley
supercluster, based on the Mark III peculiar velocity catalog (Willick et al. 1997), is only 4 ô from
the Galactic equator, and is well separated from the canonical optical center.
Over the past decade, in particular, many attempts have been made to penetrate the ZOA
and detect galaxies. Optical plates have been searched eectively in this area (Kraan-Korteweg &
Woudt 1994; Saito et al. 1990, 1991 and Wakamatsu et al. 1994), down to jbj  4 ô . A combination
of optical and near-IR imaging appears to extend the possibility of galaxy detection to around
jbj  3 ô . Far-infrared (FIR) color selection of sources in the IRAS Point Source Catalog (Version
2, 1998, hereafter PSC) has been moderately successful in selecting candidate galaxies at lower
Galactic latitudes, jbj >2 ô (Lu et al. 1990, Saunders et al. 1994). Though these methods still
rely on follow-up observations of candidates for conrmation (e.g. in H I, Bottinelli et al. 1994),
as IRAS observations become confusion-limited close to the Plane. For jbj < 5 ô all optical and
infrared observations become very diôcult to determine and are ultimately confusion-limited.
However, in this latitude range, 21 cm observations have been very successful in nding galaxies.
Blind H I Surveys for galaxies hidden by the Milky Way were pioneered by Kerr & Henning
(1987) on the Green Bank 300 foot telescope, and have continued on the Dwingeloo 25 m telescope
(Henning et al. 1998). However, such H I surveys have been severely limited in either sensitivity
or area of sky that can be surveyed. The development of a 21 cm multibeam receiver for the
Parkes 64 m telescope 6 has changed matters. This receiver has an array of 13 feed horns (each
having two receivers observing orthogonal linear polarisations) mounted in a hexagonal pattern in
the prime focus (Staveley-Smith et al. 1996) and allows large areas to be surveyed at adequate
sensitivity in a relatively short time.
The region of sky investigated here was chosen for several reasons. The large-scale structures
that we see above the Galactic Plane (Centaurus at `  302 ô , b  22 ô ) and below the Plane (Pavo
at `  332 ô , b  24 ô ) have long suggested that a connection may exist behind our Galactic
Plane (Lahav 1994). The galaxy counts along this structure continue to increase towards the ZOA
suggesting higher densities of galaxies may be expected. A massive galaxy cluster (Abell 3627) has
been rediscovered (Kraan-Korteweg et al. 1996) to lie along this structure at b = 7 ô . This entire
region has already been searched by visual inspection for galaxies by Woudt (1998), who was
6 The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed
by CSIRO.

{ 3 {
successful in identifying galaxies at latitudes of jbj > 4 ô . It is also of interest as it may shed light
on existence or nature of the Great Attractor, predicted by Kolatt et al. (1995) and Lynden-Bell
et al. (1988) to lie near the centre of this eld.
In x 2, the H I observations and data reduction are discussed. In x 3 we discuss the galaxy
detection method and list the detected objects together with their properties. We examine the
optical and IR cross-identications in x 4. Finally in x 5 we discuss the global properties of the
galaxies, examine their 3-dimensional distribution and their relationship with previously known
large-scale structures.
2. Observations and Data Reduction
The systematic blind H I survey of the southern ZOA began using the Parkes 64 m telescope
in 1997 March 22, and is expected to be completed late in 2000 (Staveley-Smith et al. 1998). The
relevant observations presented here were made during March to May 1997. These data represent
about 16% of the nal survey integration time and 17% of the area coverage. The ZOA \shallow
survey" of Henning et al. (1999) covers the entire southern ZOA, but with only 8% of the nal
survey integration time. The 21 cm multibeam instrument has a beamwidth of 14: 0 3 (FWHP) and
the receiver system temperature is 20 K on average. The multibeam correlator has a bandwidth of
64 MHz and covers the frequency range of 1362.5 to 1426.5 MHz. This corresponds to a velocity
(cz) range of 1200 to 12700 km s 1 . The channel spacing is 13 km s 1 . The sensitivity in the
velocity range between -100 to +100 km s 1 is signicantly lower due to Galactic H I. The velocity
resolution is 18 km s 1 or 26 km s 1 for Hanning-smoothed data (discussed in x 3.2).
Three standard elds, 8 ô  10 ô in size and centered on Galactic longitudes 312 ô , 320 ô and
328 ô make up the data for the 240 square degree eld presented here. The observations are
Nyquist sampled and then gridded together into a single cube using specially developed aips++
routines (Barnes 1998).
Each of the 3 standard data elds, which make up the data cube, has been observed on four
occasions following the scan pattern shown in Figure 1. Each eld is made up of 17 scans with each
scan being equivalent to an observation of one strip in Galactic longitude, 1: ô 7 wide and 8 ô long.
The receiver is rotated 15 ô with respect to the Galactic equator and each subscan is translated 35 0
in Galactic latitude. This results in full Nyquist-sampling of the sky and an eective integration
time for each point, over the whole region 308 ô  l  332 ô , -5 ô  b  +5 ô of 200 s. The nal data
cube has an rms noise of 20 mJy beam 1 (without Hanning smoothing).
The data were bandpass-calibrated, velocity-shifted to the heliocentric frame and baseline-
subtracted (DC oset only) using a realtime system based on aips++ (Barnes et al. 1998). Then
a `top-hat' median gridding algorithm with top-hat radius of 6 0 was used. The post-gridding
beamwidth is 15: 0 5 and the pixel size in the cubes is 4 0  4 0 . Further data inspection and analysis

{ 4 {
were carried out miriad 7 and the karma visualisation tool kview (Gooch 1995).
3. Cube Analysis and Results
3.1. Search method
The data cube was searched visually. No Hanning smoothing was applied and only zero'th
order baseline subtraction was used. kview was used to inspect the data cube, which was searched
in all the three possible planes i.e. along the RA, Dec and velocity axis respectively. Sources
which were found in only one of the above planes were rechecked and often not conrmed { noise
and interference are the principal reason for false detections.
The application of this process resulted in a catalog of candidate sources for H I galaxies. We
then used the MIRIAD task IMSTAT to determine the cube rms noise in patches free of detectable
sources. The lower peak brightness limit for the nal catalog was then set at 3 times the rms noise
per channel (60 mJy beam 1 ) for the unsmoothed data.
3.2. Galaxy Properties
In Table 1 all the relevant H I data and derived properties of the 42 galaxies found in the
blind survey have been compiled. The Hanning smoothed H I proles of the detected galaxies are
illustrated in Figure 2.
An explanation of the parameters displayed in Table 1 follows.
Column 1: Source name. Sources marked by ( a ) have more accurate ATCA data listed in
Staveley-Smith et al. (1998).
Columns 2 & 3: Equatorial coordinates (J2000). This is the Gaussian-tted position of the
H I source, using a total intensity image. The resulting positional uncertainty of the source is  3 0 .
Columns 4 & 5: Galactic coordinates corresponding to the source position.
Column 6: The velocity (cz) is in the heliocentric reference frame. The radial velocity
(km s 1 ) corresponds to the midpoint of the H I prole calculated at 50% of the peak brightness
value. The uncertainty in the velocity is 10 km s 1 .
Column 7: Velocity width at 50% peak brightness. The velocity width for each source was
calculated from the spectra obtained from IMSPEC. A constant correction of 6 km s 1 was
subtracted from the velocity widths to compensate for instrumental resolution of 18 km s 1 and
7 Multichannel Image Reconstruction, Image Analysis and Display package (Sault, Teuben & Wright 1995).

{ 5 {
based on a dispersion of the H I gas of about 10 km s 1 . Similar corrections are applied by Fisher
& Tully (1981). The uncertainty for 50% widths is 20km s 1 .
Column 8: Distance (d), with respect to the Local Group
H ô d = cz + 300 sin l cos b
We assume a H ô = 75 km s 1 Mpc 1 throughout this paper. No corrections were made for
streaming motions.
Column 9: Integrated ux densities (in units of Jy km s 1 ) were calculated using MIRIAD. A
total power image was created for each source by combining (adding) velocity planes. The range
in velocity used was detemined by the velocity width of the source dened in Column 5 above.
The source ux was then spatially integrated. The rms uncertainty in the integral is typically
20%, but larger in the case of objects with weak proles and residual baseline curvature as shown
in Figure 2.
Column 10: H I mass of source, calculated from the integrated ux density and distance.
Figure 2 shows the H I velocity proles of each source from Table 1. The velocity axis is in
km s 1 (cz). The spectrum for each source was calculated by MIRIAD task IMSPEC over a given
region of the source. The spectra have been Hanning smoothed.
Of the 42 galaxies above, four galaxies are well resolved by the Parkes beam. If the eective
major axis of the galaxy was measured to be larger than 22 0 , then the source is listed as resolved
and a H I diameter is measured. This allowed a calculation of the total mass of the galaxy (Table
2), which is a lower limit in the case of the three galaxies without measured inclinations. Table 2
lists the properties of the four galaxies. The columns are:
Column 1: Source name, as in Table 1.
Column 2: The H I diameter of the source measured at the 50% peak column density contour
level.
Column 3: The lower limit to the total mass
M T = 2.3310 5 R kpc V 2
rot
as used here, assumes a rotational velocity (V rot ) that is approximated by V rot =
0.5
V 50 (csc i)
The inclination (i) has been obtained from the WKK (Woudt 1998) catalog (described in
x 4.1). If an optical counterpart could not be found an inclination of 90 ô is assumed ( a ) and the
mass is a lower limit.
Column 4: H I mass to total mass ratio, expressed as a percentage.
Column 5: Estimate of morphology, based on the H I mass-to-total mass ratio in column

{ 6 {
4 and the values listed in Roberts & Haynes (1994). The morphology classication of HIZOA
J1616-55 is extremely uncertain.
3.3. Unusual Systems
Several of the detected galaxies have very unusual characteristics, suggesting interactions or
mergers in progress, three of which are:
HIZOA J1416-58: this is a low H I ux (peak brightness  70 mJy) galaxy with a huge
velocity width of 685 km s 1 . Follow-up observations are underway with the ATCA.
HIZOA J1532-56 is the rst galaxy found to have a Galactic latitude of 0:0 ô in the area
of the Great Attractor. It is hidden by 70 mag of extinction in B-band as given by the 100m
DIRBE/IRAS maps (Schlegel, Finkbeiner & Davis 1998). It appears well-resolved by the Parkes
beam and shows unusual structure in the velocity planes. This galaxy has already been observed
with ATCA (Staveley-Smith et al. 1998), showing it to be an interacting system.
HIZOA J1616-55: this system is nearby (3.3 Mpc, v=403 km s 1 ) and large (44 kpc).
Although classied as an LSB type (Table 2), observations with the ATCA (Staveley-Smith et al.
1998) have shown that it is likely to be an interacting pair of low mass H I galaxies.
4. Optical and Far-Infrared Cross Identications
4.1. Optical Counterparts
In looking for optical counterparts to the H I detected galaxies we dene:
(a) associations - optically identied sources which are within a 6 0 radius of the H I position;
(b) identications - sources which are within a 6 0 radius of the H I position and which have
measured velocities in agreement with the H I velocities. This terminology is used throughout this
paper.
The search for optical counterparts was made in two ways: rst using NED 8 , then using the
WKK optical catalogue. The WKK galaxies were identied by visual inspection of IIIaJ lm
copies of the SRC sky survey (Woudt 1998). This search resulted in identifying 8 galaxies and a
further 9 associations.
Table 3 lists the known optical parameters of the candidates. The columns are:
Column 1: Source name, as in Table 1.
8 The NASA/IPAC Extragalactic Database (NED) is operated by the Jet Propulsion Laboratory, California
Institute of Technology, under contract with the National Aeronautics and Space Administration.

{ 7 {
Column 2: Optical association Name. All ESO galaxies shown have also been correlated with
WKK galaxies.
Column 3: Radial oset in arcmin from H I position.
Column 4: Velocity (cz) in km s 1 . Velocities shown for WKK galaxies are from Woudt &
Kraan-Korteweg (2000) and those for ESO galaxies are from NED. Velocities marked with ( a ) are
not yet published and may not be nal.
Column 5: Inclination angle calculated according to Holmberg (1946):
cos 2 i = (r 2 r 2
ô )(1 r 2
ô ) 1
where r is the observed minor/major axial ratio ( b
a ) and r ô is the intrinsic attening. We
assume r ô = 0.2 (e.g. Richter & Huchtmeier (1984). The inclinations are most likely lower limits
compared to the true inclinations (Kraan-Korteweg 1992) as extinction obscures the extent of the
faint disks more eectively then the bulges.
Column 6: Estimate of morphological type as given by the WKK or ESO catalogues. The
ESO galaxy classication has been conrmed with the WKK catalogue morphology classications.
Column 7: B J magnitude as given in Woudt (1998).
Column 8: B-Band extinction in magnitudes derived from the 100m DIRBE/IRAS data
(Schlegel et al. 1998) for each H I position. These data provide a direct measure of the dust
column density. Therefore, in this case, the gas-to-dust ratio is not important. We have used the
DIRBE/IRAS data to determine extinction instead of H I column densities because the Galactic
H I line might be saturated and therefore give an underestimate of the value for extinction at these
latitudes. We do note that the DIRBE/IRAS data are not well calibrated in the ZOA and should
be used with caution.
4.2. IRAS Counterparts
As most of the galaxies we have detected are totally obscured optically, we look for infrared
associations to gain a better understanding of the galaxies. We have done this in three ways:
(i) IRAS PSC associations with optically identied galaxies;
(ii) IRAS PSC associations with H I galaxy positions; and
(iii) examining the IRAS Galaxy Atlas (IGA, Cao et al. 1997) data.
We rst searched the Woudt (Woudt 1998) catalog of optically identied galaxies. This
catalog has already been cross correlated with the IRAS PSC using a search radius of 2 0 . The
search resulted in 13 H I galaxies having both optical and infrared associations, 3 having tentative
IRAS associations and 4 having only optical associations.
Those galaxies for which we did not nd any association in the Woudt catalogue were looked

{ 8 {
at in the IRAS PSC with a 6 0 search radius. The search resulted in a list of possible IRAS
associations. In some cases more then one infrared source was found in the search radius. To
determine if the IRAS source could be a real association we have used two further selection
criteria: (i) the source must have 2 or more ux densities out of the 4 IRAS bands (i.e. we do
not accept sources with only one ux density and three upper limits); and (ii) it must have IRAS
color characteristics of a galaxy (Yamada et al. 1993a,b). Sources that fail these criteria have been
dropped from Table 4.
Finally we have used the IGA (super-resolved IRAS data). The IGA has a resolution of
1 0 2 0 , and provides a three-fold improvement in linear resolution relative to the IRAS Sky Survey
Atlas (ISSA). This was of particular interest as in some cases there were several faint sources in
the region of the H I contours. We overlayed H I total intensity contours over the IGA at both 60
and 100m bands. This allowed us to determine whether any of the IRAS associations that were
rejected by criterion (i) were real. Four such IRAS sources were found in the IGA images. For
these source uxes were calculated from the IGA data. Also upper limits at 100m for 3 IRAS
sources, which passed our criteria, have been revised and recalculated from the IGA.
The integrated ux densities from the IGA bands (IGA uxes were rst converted to Jy
pixel 1 ) were calculated using MIRIAD task CGCURS by integrating over a patch of the visible
extent of the source. To subtract any background due to the Galaxy, an annulus was made around
the source, avoiding any other source ux. This was used to calculate average and maximum ux
for the background.
Table 4 lists the IRAS associations made with the H I galaxies and their ux densities.
Column 1: Source name, as in Table 1.
Column 2: The IRAS association name from the IRAS PSC.
Column 3: Radial oset of the IRAS source from the H I position.
Columns 4,5,6,7: IRAS ux densities in the 12, 25, 60, 100m IRAS bands, and their
uncertainties. 16 galaxies have been associated with IRAS PSC sources fullling the requirements
described in this section.
4.3. H I positional accuracy
The dierence between the H I and optical/IRAS position, in Right Ascenstion (R.A.) and
Declination (Dec.) coordinates, is shown in Figure 3. The mean R.A. oset is 1: 0 7 with an rms of
1: 0 4, and in Dec. it is 1: 0 6 and 1: 0 1 respectively. This corresponds to between 10 and 20% of the 14: 0 3
FWHP beam of the Parkes telescope. There may be a small number of false associations. This
will be further investigated in the full sensitivity survey data.

{ 9 {
5. Discussion
The 42 detected galaxies have an H I mass range between about 4  10 7 and 3  10 10 M
(h 2
75 ). Assuming a mean linewidth of 100 km s 1 , the H I mass limit at the 3 level is MHI =
1.510 6 d 2
Mpc M . Figure 4 shows the approximate lower H I mass limit for each velocity in our
range.
Although only 8 have been previously cataloged with velocities, we have tentatively found
optical and far-infrared counterparts for a further 12 galaxies. The median extinction for the 20
galaxies with counterparts is AB = 3:8 mag (Table 3). For the remaining unidentied galaxies, it
is AB = 5:6 mag. The fact that some galaxies with apparently moderate extinction (< 4 mag) are
unidentied is perhaps not surprising, owing to the preference for H I-selected samples to favour
low optical surface brightness objects. However, it should also be noted that the Schlegel et al.
(1998) extinctions are poorly calibrated in the Plane.
The galaxies range in velocity up to 6000 km s 1 as shown in the histogram in Figure 5. This
upper limit corresponds to the sensitivity limit of the existing data (the nal ZOA survey will
have six times more integration time). The histogram shows distinct peaks at 1250, 3000 and
5250 km s 1 . Although, due to the limited nature of the sample, the statistical signicance of the
suggested overdensities in Figure 5 is low, nevertheless the rst two redshift peaks seem to match
the expected peaks due to the Local Supercluster and the Centaurus and Pavo superclusters,
respectively. In our sample, the main concentration of galaxies (45%) is in the velocity range 2500
to 4000 km s 1 as might be expected if there exists a continuous bridge of galaxies stretching
between the Centaurus and Pavo superclusters behind the Galactic Plane.
The spatial distribution of the galaxies is shown in Galactic coordinates in Figure 6. The
galaxies with optical and IRAS associations populate the diagram away from 0 ô latitude. Galaxies
with only a H I detection lie closer to 0 ô , although they may still be discriminated against owing
to higher system temperatures and continuum confusion within a degree of the Plane. The
distributions in velocity (Figure 5) and on the sky (Figure 6) become more interesting when
plotted with previously published data over a wider region. The distribution of all optically
identied galaxies within 6000 km s 1 , as given by the Lyon-Meudon Extragalactic Data Base 9
(LEDA), is shown in Figure 7 together with the new galaxies. The Centaurus (302 ô , 22 ô ) and
Pavo II (332 ô , 24 ô ) clusters are clearly seen, but the A3627 overdensity at (325 ô , 7 ô ) is not so
clearly seen in the LEDA data. However, the new detections show some evidence for continuity of
the Centaurus lamentary structure, a continuous bridge of galaxies stretching from the Centaurus
supercluster, behind the ZOA, in the general direction of the Pavo cluster.
The galaxies detected along the suggested Centaurus-Pavo bridge are better seen in the cone
diagrams shown in Figure 8. From the Centaurus cluster, there seems to be an increase of median
9 We have made use of the Lyon-Meudon Database (LEDA) supplied by the LEDA team at the CRAL-Observatoire
de Lyon (France).

{ 10 {
redshift as longitude increases and latitude decreases in such a manner that a continuous bridge
is again suggested. The new H I data, when considered alone, suggest a more continuous cellular
structure from 3000 to 6000 km s 1 , with Centaurus at the edge of the cell wall. However, the
combined data show a more complex structure which is undoubtedly due, in part, to the patchy
and incomplete nature of the optical redshift observations.
Given the caveats about the completeness and shallowness of the present survey, it is of
interest to compare the present data with the potent prediction by Kolatt et al. (1995) that
the central peak of the Great Attractor should lie at (l; b; cz) = (320 ô ; 0 ô ; 4000 km s 1 ). Whilst a
broad overdensity exists at  4000 km s 1 in the current data (Figure 5), there is no compelling
evidence for any discrete structure, previously hidden by the Galactic Plane, providing the bulk of
the Great Attractor mass. The best candidate for this remains the A3627 cluster (Kraan-Korteweg
et al. 1996), though, with an estimated mass of 0.4 { 2:2  10 15 M (Boehringer et al. 1996), the
cluster itself provides only a small part of the gravitational acceleration required to explain the
motions of galaxies in the nearby Universe.
6. Summary
We have cataloged positions and redshifts for 42 galaxies in a blind H I survey of a small
part of the southern Zone of Avoidance (ZOA). Only 8 of these have previous redshifts, although
a subsequent search at the H I positions has led to a further 12 (some tentative) optical or IRAS
associations. The H I data allow galaxies to be found closer to the Galactic Plane than previously
possible. The H I data show that there exists a general overdensity of galaxies between 2500 and
4000 km s 1 , suggestive of a continuous bridge of galaxies stretching between the Centaurus and
Pavo superclusters behind the Galactic Plane. However, no dramatic new structure is revealed
in the velocity and H I mass range explored here. The full-sensitivity multibeam survey of this,
and surrounding ZOA regions is underway and should allow us to extend the redshift range of the
search and better quantify the apparent overdensity of galaxies.
We thank members of the HIPASS team for their tremendous observing assistance, Ian
Stewart and many others at Parkes for their support at the telescope, and Taisheng Ye, David
Barnes, Richard Gooch and the aips++ team for software support. We thank Patrick Woudt for
the use of the WKK catalogue from his PhD thesis. Sebastian Juraszek would like to acknowledge
partial support from an ARC scholarship. The research of Dr P.A. Henning is supported by NSF
Faculty Early Career Development (CAREER) Program award AST 95-02268.

{ 11 {
REFERENCES
Barnes, D.G. 1998, in ASP Conf. Ser. 145, Astronomical Data Analysis Software and Systems
VII, ed. R. Albrecht, R. N. Hook, & H. A. Bushouse (San Francisco: ASP), 32
Barnes, D.G., Staveley-Smith, L., Ye, T., & Oosterloo, T. 1998, in ASP Conf. Ser. 145,
Astronomical Data Analysis Software and Systems VII, ed. R. Albrecht, R. N. Hook, & H.
A. Bushouse (San Francisco: ASP), 89
Beichman, C.A., Neugebauer G., Habing H.J., Clegg P.E., & Chester T.J. 1985, Explanatory
Supplement to the IRAS Catalogues and Atlases, US Government Printing Oôce,
Washington DC
Boehringer, H., Neumann, D.M., Schindler, S., & Kraan-Korteweg, R.C. 1996, ApJ, 467, 168
Bottinelli, L., Gouguenheim, L., Loulergue, M., Martin, J.M., Theurean, G., Paturel, G. 1994,
in ASP Conf. Ser. 67, Unveiling Large-Scale Structures behind the Milky Way, ed. C.
Balkowski, & R. C. Kraan-Korteweg (San Francisco: ASP), 225
Cao, Y., Terebey, S., Prince, T. A. & Beichman, C. A. 1997, ApJS, 111, 387
Fisher, J.R. & Tully, R.B. 1981, ApJS, 47, 139
Gooch, R.E. 1995, Workshop on Applications of Radio Science, Australia Academy of Science
through the National Committee for Radio Science
Henning, P.A., Kraan-Korteweg, R.C., Rivers, A.J., Loan, A.J., Lahav, O., & Burton, W.B. 1998,
AJ, 115, 584
Henning, P.A., Staveley-Smith, L., Ekers R., Green, A.J., Haynes, R., Juraszek, S., Kesteven, M.,
Koribalski, B., Kraan-Korteweg, R.C., Price, M., Sadler E.M., Schroder, A. 1999, AJ, in
preparation
Holmberg E. 1946, Medd. Luna Obs. II, 117
IRAS Point Source Catalogue Version 2, Joint IRAS Science Working Group (eds.) 1988, GPO,
Washington DC
Kerr, F.J., & Henning, P.A. 1987, ApJ, 320, L99
Kolatt, T., Dekel, A., & Lahav, O. 1995, MNRAS, 275, 797
Kraan-Korteweg, R.C. & Huchtmeier, W.K. 1992, A&A, 266, 150
Kraan-Korteweg, R.C. & Woudt, P.A. 1994, in ASP Conf. Ser. 67, Unveiling Large-Scale
Structures behind the Milky Way, ed. C. Balkowski, & R. C. Kraan-Korteweg (San
Francisco: ASP), 89
Kraan-Korteweg, R.C., Woudt, P.A., Cayatte, V., Fairall, A.P., Balkowski, C. & Henning P.A.
1996, Nature, 379, 519
Lahav, O. 1994, in ASP Conf. Ser. 67, Unveiling Large-Scale Structures behind the Milky Way,
ed. C. Balkowski, & R. C. Kraan-Korteweg (San Francisco: ASP), 7

{ 12 {
Lynden-Bell, D., Faber, S.M., Burstein, D., Davies, R. L., Dressler, A., Terlevich, R.J., & Wegner,
G. 1988, ApJ, 326, 19
Lu, N.Y., Dow, M.W., Houck, J.R., Salpeter, E.E., & Lewis, B.M. 1990, ApJ, 357, 388
Marinoni, C., Monaco, P., Giuricin, G., & Costantini, B. 1998, ApJ, 505, 484
Richter, O.G., & Huchtmeier, W.K. 1984, A&A, 132, 253
Roberts, M.S., & Haynes, M.P. 1994, ARA&A, 32, 115
Saito, M., Ohtani, H., Asonuma, A., Kashikawa, N., Maki, T., Nishida, S., & Watanabe, T. 1990,
PASJ, 42, 603
Saito, M., Ohtani, H., Baba, A., Hotta, H., Kameno, S., Kurosu S., Nakada, L., & Takata, T.
1991, PASJ, 43, 449
Sault, R.J., Teuben P.J., & Wright M.C.H. 1995, in ASP Conf. Ser. 77, Astronomical Data
Analysis Software and Systems IV, , ed. R.A. Shaw, H.E. Payne, & J.J.E. Hayes (San
Francisco: ASP), 433
Saunders, W., Sutherland, W.J., Efstathiou, C., Tadros, H., Maddox, S., Mcmahon, R.G., White,
S.D.M., Rowan-Robinson, M., Oliver, S.J., Keeble, O., Frenk, C.S., & Smoker, J.V. 1994,
in ASP Conf. Ser. 67, Unveiling Large-Scale Structures behind the Milky Way, ed. C.
Balkowski, & R. C. Kraan-Korteweg (San Francisco: ASP), 257
Schlegel, D.J., Finkbeiner, D.P. & Davis, M. 1998, ApJ, 500, 525
Staveley-Smith, L., Wilson, W.E., Bird, T.S., Disney, M.J., Ekers, R.D., Freeman, K.C., Haynes,
R.F., Sinclair, M.W., Vaile, R.A., Webster, R.L., & Wright, A.E. 1996, PASA, 13, 243
Staveley-Smith, L., Juraszek, S., Koribalski, B.S., Ekers, R.D., Green, A.J., Haynes, R.F.,
Henning, P.A., Kesteven, M.J., Kraan-Korteweg, R.C., Price, R.M. & Sadler, E.M. 1998,
AJ, 116, 2717
Wakamatsu, K., Hasegawa, T., Karoji, H., Sekiguchi, K., Menzies, J.W., Malkan, M. 1994, in ASP
Conf. Ser. 67, Unveiling Large-Scale Structures behind the Milky Way, ed. C. Balkowski,
& R. C. Kraan-Korteweg (San Francisco: ASP), 131
Willick, J.A., Courteau S., Faber, S.M., Burstein D., Dekel, A., & Strauss, M.A. 1997, ApJS, 109,
333
Woudt, P.A., & Kraan-Korteweg, R.C. 2000, in preparation
Woudt, P.A. 1998 Ph.D. thesis, Univ. of Cape Town
Yamada, T., Takata, T., Djamaluddin, T., Tomita, A., Aoki, K., Takeda, A., & Saito, M. 1993a,
MNRAS, 262, 79
Yamada, T., Takata, T., Djamaluddin, T., Tomita, A., Aoki, K., Takeda, A., & Saito, M. 1993b,
ApJS, 89, 57
This preprint was prepared with the AAS L A T E X macros v4.0.

{ 13 {
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
01 01
0000000000000000000000011111111111111111111111
0000000000000000000000000000011111111111111111111111111111
Equator
Galactic
Region
332 o 324 o 316 o 308 o
17 scans / field
One Field
+5.5 o
o
Galactic Longitude
Galactic
Latitude
­5.5
Fig. 1.| The region surveyed. One eld (an 8 ô  10 ô area) is scanned in Galactic longitude 17
times. Each eld overlaps the next by  2 ô . The elds are then mosaiced to form the whole region.

{ 14 {
Fig. 2.| Integrated HI line proles of the 42 galaxies detected in the survey.

{ 15 {
Fig. 2.| Continued.

{ 16 {
D
d
(arcmin)
(arcmin)
D a
Fig. 3.| The oset between the HI position and optical or IRAS association. The dashed line
marks the size of a single 4 0  4 0 pixel from the HI data. ô : galaxies which have been optically
identied (position and redshift coincidence). 4 : galaxies associated with IRAS sources.  :
galaxies with optical associations (position coincidence only).
M
(x10
)
HI
9
Velocity (km s )
­1
Fig. 4.| The line shows the approximate lower limit to the H I mass as a function of velocity
assuming a ux density of 60 mJy and linewidth of 100 km s 1 . Dots mark the H I detected
galaxies. Some fall below the line as their velocity widths are less the 100 km s 1 .

{ 17 {
Velocity Bins (500 km / s)
Galaxy
Count
Fig. 5.| Velocity histogram of the H I detected galaxies in 500 km s 1 bins.
Galactic Longitude ( )
l o
Galactic
Latitude
(
)
o
b
Fig. 6.| Distribution, in Galactic coordinates, of all H I detected galaxies. ô : detections only
found in H I, 2 : detections associated with optical and IRAS galaxies, 4 : associated only with
IRAS sources,  : detections with only optical associations.

{ 18 {
b
o
l o
Galactic Longitude ( )
Galactic
Latitude
(
)
Fig. 7.| The distribution, in Galactic coordinates, of all optically identied galaxies with velocities
within 6000 km s 1 (Lyon-Meudon Extragalactic Data Base) (dots). The new H I-detected galaxies
(circles) are overlaid (previously known galaxies are lled circles). The dashed rectangle marks the
extent of the region surveyed.

{ 19 {
l
b b
l
Fig. 8.| Top left: a cone diagram of the distribution in Galactic latitude and redshift (corrected to
the Local Group frame) for the 42 galaxies detected. Top right: the latitude-redshift distribution
including previously known galaxies (from LEDA) over a wider region, 30 ô < b < 30 ô . Bottom
left: the Galactic longitude-redshift distribution for the new galaxies. Bottom right: the longitude-
redshift distribution of previously known galaxies over a wider region 280 ô < l < 360 ô . The
Centaurus and Pavo clusters stand out as `ngers of God' at (l; b) = (302 ô ; 22 ô ) and (332 ô ; 24 ô ),
respectively.

{ 20 {
Table 1. HI Data and Properties
Name R.A. Dec. Gal. Gal. Vel. Vel. Dist. Flux HI Mass
(J2000) (J2000) Long. Lat. Helio. Width (LG) Integral
(cz) @50%
h m s d m s deg. deg. km s 1 km s 1 Mpc Jy km s 1 10 9 M
HIZOA J1327 57 13 27 26 57 32 50 307.76 +4.99 2903 177 35.6 17.0 5.1
HIZOA J1333 58 13 33 00 58 04 57 308.42 +4.35 1478 115 16.6 12.6 0.8
HIZOA J1337 58 13 37 16 58 30 35 308.90 +3.83 4125 158 51.9 13.3 8.4
HIZOA J1341 58 13 41 48 58 49 03 309.42 +3.42 3861 144 48.4 6.0 3.3
HIZOA J1342 61 13 42 12 61 02 03 309.04 +1.23 3963 320 49.7 23.2 13.5
HIZOA J1344 65 13 44 52 65 39 59 308.40 3.36 2769 331 33.8 31.2 8.4
HIZOA J1347 58 13 47 19 58 11 09 310.26 +3.89 3672 198 45.9 7.4 3.7
HIZOA J1351 58 13 51 40 58 39 36 310.71 +3.30 3848 604 48.3 25.5 14.0
HIZOA J1358 58 13 58 43 58 50 04 311.56 +2.91 4017 42 50.6 2.4 1.4
HIZOA J1407 58 14 07 47 58 41 53 312.72 +2.71 3220 62 40.0 5.5 2.1
HIZOA J1413 65 14 13 26 65 19 12 311.36 3.80 449 246 3.0 1963.5 4.1
HIZOA J1414 62 14 14 46 62 56 29 312.25 1.59 3260 56 40.5 4.0 1.5
HIZOA J1416 58 14 16 03 58 52 36 313.69 +2.22 5405 685 69.2 22.5 25.4
HIZOA J1417 55 14 17 10 55 37 12 314.89 +5.25 3943 374 49.7 18.6 10.8
HIZOA J1419 58 14 19 40 58 10 26 314.37 +2.73 3936 381 49.6 20.5 11.9
HIZOA J1432 55 14 32 03 55 28 22 316.92 +4.64 3105 157 38.7 9.6 3.4
HIZOA J1436 63 14 36 02 63 07 31 314.44 2.61 1545 102 17.7 12.4 0.9
HIZOA J1448 57 14 48 12 57 36 30 318.08 +1.79 4805 199 61.4 6.2 5.5
HIZOA J1450 55 14 50 17 55 15 18 319.38 +3.78 5528 146 71.1 4.2 5.0
HIZOA J1452 56 14 52 59 56 45 50 319.04 +2.26 3267 305 40.9 19.5 7.7
HIZOA J1457 54 14 57 15 54 23 23 320.67 +4.09 2877 479 35.8 21.5 6.5
HIZOA J1458 55 14 58 32 55 08 08 320.48 +3.35 5200 166 66.8 7.2 7.6
HIZOA J1501 60 15 01 22 60 42 52 318.17 1.75 4444 117 56.6 13.3 10.0
HIZOA J1504 55 15 04 25 55 28 52 321.05 +2.64 5248 50 67.5 4.6 4.9
HIZOA J1505 54 15 05 59 54 23 40 321.78 +3.48 2937 130 36.7 9.6 3.0
HIZOA J1508 60 15 08 10 60 45 50 318.87 2.20 4505 274 57.4 19.2 14.9
HIZOA J1509 52 15 09 16 52 34 29 323.12 +4.81 1445 348 16.9 30.3 2.0
HIZOA J1514 52 a 15 14 37 53 00 53 323.59 +4.02 1445 428 16.9 152.6 10.3
HIZOA J1514 60 15 14 50 60 33 33 319.68 2.44 5146 363 66.0 12.0 12.3
HIZOA J1518 55 15 18 24 55 37 50 322.68 +1.50 1491 235 17.5 12.4 0.9
HIZOA J1526 51 15 26 20 51 11 16 326.09 +4.58 615 21 6.0 4.7 0.04
HIZOA J1532 56 a 15 33 03 56 04 07 324.14 +0.00 1365 55 15.9 28.2 1.7
HIZOA J1536 56 15 36 35 56 25 20 324.34 0.57 2722 176 34.0 11.7 3.2
HIZOA J1540 50 15 40 17 50 48 42 328.11 +3.62 5323 77 68.9 6.2 7.0
HIZOA J1543 60 15 43 11 60 13 37 322.76 4.14 5193 241 66.8 13.4 14.1
HIZOA J1543 58 15 43 14 58 45 28 323.66 2.98 2897 143 36.3 11.3 3.5
HIZOA J1547 59 15 47 14 59 04 23 323.87 3.55 5631 310 72.7 10.3 12.8
HIZOA J1547 57 15 47 18 57 16 05 325.00 2.13 2769 89 34.6 6.5 1.8
HIZOA J1550 58 15 50 28 58 26 18 324.60 3.31 2059 109 25.1 5.5 0.8
HIZOA J1605 57 16 05 24 57 51 12 326.48 4.14 2991 89 37.7 15.1 5.0
HIZOA J1612 56 16 12 44 56 23 48 328.20 3.74 2729 291 34.3 11.2 3.1
HIZOA J1616 55 a 16 18 16 55 36 49 329.30 3.72 403 101 3.3 31.4 0.08
a These galaxies have names derived from the more accurate ATCA positions (Staveley-Smith et al. 1998).

{ 21 {
Table 2. H I derived Properties
Name H I Indicative MHI/M total Morphology Identication
Diameter Total Mass Estimate
kpc 10 10 M %
HIZOA J1413 65 32 7.4 5.6 Sc,Sd Circinus
HIZOA J1436 63 a 95 >5.7 <1.6 Sa
HIZOA J1532 56 a 108 >1.9 <8.9 Sc,Sd
HIZOA J1616 55 a 44 >2.6 <0.4 LSB
a i = 90 ô assumed.

{ 22 {
Table 3. Optical Data
Name Optical Oset Velocity Inclination Source Extinction B J
Association Morphology (B-band)
< 6 0 arcmin km s 1 deg. mag mag
HIZOA J1327 57 ESO 173 G015 3.5 3006 82 S 16.3 3.5
HIZOA J1333 58 3.4
HIZOA J1337 58 3.9
HIZOA J1341 58 3.8
HIZOA J1342 61 10.5
HIZOA J1344 65 WKK 2503 1.3 63 S 15.2 3.8
HIZOA J1347 58 4.7
HIZOA J1351 58 WKK 2596 4.3 3867 a 72 S 17.8 4.4
HIZOA J1358 58 3.2
HIZOA J1407 58 9.1
HIZOA J1413 65 Circinus 4.3 436 74 S 11.5 6.1
HIZOA J1414 62 13.1
HIZOA J1416 58 8.6
HIZOA J1417 55 WKK 3103 4.6 3954 82 S 15.0 2.7
HIZOA J1419 58 WKK 3132 4.1 75 S 19.6 6.6
HIZOA J1432 55 ESO 175 G009 1.1 3019 19 SB 14.6 3.6
HIZOA J1436 63 4.6
HIZOA J1448 57 7.3
HIZOA J1450 55 WKK 4352 2.8 42 S 17.6 4.0
HIZOA J1452 56 6.9
HIZOA J1457 54 WKK 4470 1.3 2877 a 80 S 15.6 3.7
HIZOA J1458 55 WKK 4491 2.6 70 S 18.2 3.8
HIZOA J1501 60 8.3
HIZOA J1504 55 6.2
HIZOA J1505 54 4.3
HIZOA J1508 60 5.6
HIZOA J1509 52 ESO 223 G012 3.5 1283 88 S 14.1 3.3
HIZOA J1514 52 WKK 4748 1.7 1451 a 80 S 13.9 4.3
HIZOA J1514 60 6.1
HIZOA J1518 55 14.2
HIZOA J1526 51 2.7
HIZOA J1532 56 69.1
HIZOA J1536 56 33.3
HIZOA J1540 50 WKK 5182 2.7 34 E 17.4 3.6
HIZOA J1543 60 WKK 5229 4.9 75 S 15.8 3.1
HIZOA J1543 58 4.9
HIZOA J1547 59 WKK 5285 0.8 54 S 17.1 2.8
HIZOA J1547 57 6.0
HIZOA J1550 58 WKK 5366 3.9 74 S 16.4 3.1
HIZOA J1605 57 WKK 5834 1.4 60 S 17.0 2.1
HIZOA J1612 56 2.3
HIZOA J1616 55 2.8
a Velocities from Woudt & Kraan-Korteweg (2000), may not be nal.

{ 23 {
Table 4. IRAS Data
Name IRAS Oset IRAS ux densities a
Association 12m 25m 60m 100m
< 6 0 arcmin Jy Jy Jy Jy
HIZOA J1327 57 IRAS 13242 5713 4.0 1.21B 7.52B 76.32C 89.86D
HIZOA J1341 58 IRAS 13386 5832 2.8 0.37C 0.86C 3.95D 4.04G
HIZOA J1344 65 IRAS 13413 6525 1.1 0.38L 1.07C 7.81C 13.47C
HIZOA J1351 58 IRAS 13483 5820 4.8 0.25L 0.25L 1.22D 19.26G
HIZOA J1413 65 IRAS 14092 6506 5.5 18.80B 68.44B 248.70C 315.90C
HIZOA J1417 55 IRAS 14137 5518 5.3 0.28L 0.25E 2.56C 7.10C
HIZOA J1419 58 IRAS 14159 5755 3.3 0.45L 0.25L 1.59C 2.84G
HIZOA J1432 55 IRAS 14284 5514 1.9 0.34C 0.53D 6.06C 13.23C
HIZOA J1450 55 IRAS 14464 5501 4.2 0.41L 0.25L 0.94C 2.75G
HIZOA J1452 56 IRAS 14492 5634 1.1 0.27L 0.45C 3.89C 4.05G
HIZOA J1457 54 IRAS 14535 5411 1.7 0.40L 0.25L 1.60B 6.69E
HIZOA J1509 52 IRAS 15058 5221 3.0 0.38L 0.33B 4.44B 17.80C
HIZOA J1514 52 IRAS 15109 5248 1.6 0.79C 0.99B 18.23C 60.23C
HIZOA J1518 55 IRAS 15147 5527 1.4 1.73L 1.07L 2.19D 6.31G
HIZOA J1540 50 IRAS 15364 5038 3.3 0.51L 0.45C 3.31C 5.22G
HIZOA J1547 59 IRAS 15431 5855 0.5 0.43L 0.32F 2.11E 10.02D
a The following key explains the uncertainties in the IRAS uxes (IRAS Explanatory Supplement, Beichman et al. 1985).
B: 4%  uncertainty < 8%, C: 8%  uncertainty < 12%, D: 12%  uncertainty < 16%, E: 16%  uncertainty < 20%, F:
uncertainty  20%, L: Upper Flux Limit, and G: IGA Source Flux Estimate 30% (the IGA was used when the IRAS PSC
gave only upper limits at 60 and 100m).