Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.atnf.csiro.au/research/multibeam/papers/shallow_survey.ps.gz Äàòà èçìåíåíèÿ: Mon Mar 13 05:52:33 2000 Äàòà èíäåêñèðîâàíèÿ: Sun Dec 23 09:31:30 2007 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: m 63

Astronomical Journal, in press
H I Bright Galaxies in the Southern Zone of Avoidance
P.A. Henning, 1 L. Staveley-Smith, 2 R.D. Ekers, 2 A.J. Green, 3 R.F. Haynes, 2 S. Juraszek, 3 M.J.
Kesteven, 2 B. Koribalski, 2 R.C. Kraan-Korteweg, 4 R.M. Price, 1 E.M. Sadler, 3 A. Schroder, 5
ABSTRACT
A blind survey for H I bright galaxies in the southern Zone of Avoidance,
(212 ô  `  36 ô , jbj  5 ô ), has been made with the 21 cm multibeam receiver on
the Parkes 64 m radiotelescope. The survey, sensitive to normal spiral galaxies to a
distance of  40 Mpc and more nearby dwarfs, detected 110 galaxies. Of these, 67 have
no counterparts cataloged in the NASA/IPAC Extragalactic Database. In general,
the uncataloged galaxies lie behind thicker obscuration than do the cataloged objects.
All of the newly-discovered galaxies have H I ux integrals more than an order of
magnitude lower than the Circinus galaxy. The survey recovers the Puppis cluster and
foreground group (Kraan-Korteweg & Huchtmeier 1992), and the Local Void remains
empty. The H I mass function derived for the sample is satisfactorily t by a Schechter
function with parameters  = 1.51  0.12,   = 0.006  0.003, and log M  = 9.7 
0.10.
Subject headings: surveys { galaxies: distances and redshifts { galaxies: mass function
{ galaxies: fundamental parameters { radio lines: galaxies
1. Introduction
The obscuration due to dust and the high stellar density in our Galaxy varies from place
to place within the Milky Way. Overall, it blocks our optical view of the extragalactic Universe
over 20% of the sky, somewhat less in the infrared. This \Zone of Avoidance" (ZOA) was
recognized even before the nature of the spiral nebulae themselves was understood. This sky
1 Institute for Astrophysics, University of New Mexico, 800 Yale Blvd, NE, Albuquerque, NM 87131, USA
2 Australia Telescope National Facility, CSIRO, P.O. Box 76, Epping, NSW 2121, Australia
3 School of Physics, University of Sydney, NSW 2006, Australia
4 Departamento 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 04, France

{ 2 {
coverage limitation does not pose a problem for the study of galaxies themselves, as there is no
reason to believe that the population of obscured galaxies should dier from those in optically
unobscured regions. However, to understand the Local Group's motion requires mapping the
surrounding mass inhomogeneity, measured in practice by galaxy over- and under-densities, across
the entire sky. In particular, the lack of a full census of nearby, hidden galaxies is troublesome,
since the local galaxies should play a signicant role in the Milky Way's motion with respect to
the microwave background (Kraan-Korteweg 1993).
The ZOA has been successfully narrowed by deep searches in the optical and infrared (see
Kraan-Korteweg & Woudt 1999 for a comprehensive review of the various eorts). However,
optical searches fail where the extinction exceeds 4 - 5 magnitudes, within about jbj  < 5 ô of the
Galactic plane. Near-infrared surveys, e.g. 2MASS (Skrutskie et al. 1997) and DENIS (Epchtein
1997), will eventually produce catalogs of galaxies closer to the plane than is possible with optical
searches, but they do not recover the most heavily obscured galaxies, or galaxies of low surface
brightness (Schroder, Kraan-Korteweg, & Mamon 1999). Far-infrared surveys become confusion
limited by Galactic sources at low latitudes, and the remaining ZOA still covers  10 % of the sky.
Galaxies which contain H I can be found in the regions of thickest obscuration and IR
confusion. The technique was pioneered over a decade ago by Kerr & Henning (1987) who showed
through a small, pilot survey that completely optically-hidden galaxies could be readily uncovered
through the detection of their 21-cm emission. Since then, a spatially complete survey for spirals
out to 4000 km s 1 has been conducted over the northern ZOA (30 ô  `  220 ô , jbj  5 ô ;
rms noise 40 mJy beam 1 ) with the 25 m Dwingeloo telescope (Henning et al. 1998, Rivers et
al. 1999). The survey uncovered no massive, \Andromeda"-type galaxy in the ZOA, indeed the
nearest, previously unknown galaxy revealed by the survey was Dwingeloo 1, a likely member of
the IC342/Maei group (Kraan-Korteweg et al. 1994). The census for nearby, H I-bearing galaxies
in the northern ZOA is complete, at least for those galaxies whose redshifts or blueshifts are
suôcient to separate their H I signals from Galactic 21-cm emission, at 0  100 km s 1 .
We report here on a somewhat deeper survey (rms noise 15 mJy beam 1 ) for H I galaxies in
the southern ZOA, conducted with the new multibeam receiver on the 64 m Parkes radiotelescope
6 . The angular coverage (212 ô  `  36 ô , jbj  5 ô ) completes the survey of the great circle of the
ZOA for relatively nearby, dynamically important HI galaxies. The present survey discussed here
(the \shallow survey") represents the rst stage of an ongoing deeper search of the area with the
multibeam system. The shallow survey is comprised of the rst two scans of a planned 25 scans
of the southern ZOA, estimated to be completed in mid-2000. (This full sensitivity survey will be
sensitive to spirals to a redshift of  10,000 km s 1 ). In addition to the astronomical motivation
outlined above, the shallow survey serves as a testbed of techniques for the full sensitivity survey.
6 The Parkes telescope is part of the Australia Telescope which is funded by the Commonwealth of Australia for
operation as a National Facility managed by CSIRO.

{ 3 {
An intermediate-depth survey consisting of four scans of the region 308 ô  `  332 ô ; jbj  5 ô ,
has been conducted (Juraszek et al. 2000). This region is of particular interest as it contains the
predicted position of the core of the Great Attractor (Kolatt, Dekel, & Lahav 1995).
In x 2, the observations and data reduction will be described. The search method and galaxy
H I parametrization procedure will be outlined in x 3. The resulting catalog is presented in x 4.
Discussion of the galaxy distribution at low Galactic latitudes, the H I mass function derived for
the sample, and predictions for the full sensitivity survey are contained in x 5.
2. Observations and Data Reduction
The observations for the survey commenced on 1997 March 22 and were made by scanning
the Parkes multibeam receiver in strips of constant Galactic latitude, each of length 8 ô . The
Parkes receiver has 13 independent beams, each with two orthogonal linear polarizations. The
receiver rotation was xed (with respect to the telescope which has an alt-az mount) during
each scan such that the rotation angle of the receiver, relative to the scan direction, was 15 ô at
the mid-point of the scan. This meant that the beams rotated on the sky during each scan.
Nevertheless, there was suôcient overlap to obtain complete sampling of the entire southern Plane,
with approximately uniform sensitivity (see Staveley-Smith 1997). The absence of continuous
receiver rotation and axial focussing helped ensure maximum baseline stability. The telescope
scan rate was 1 degree/min, so each scan took 8 min to complete. The observations were
done in parallel with the H I Parkes All Sky Survey (HIPASS) and a deeper ZOA survey (see
http://www.atnf.csiro.au/research/multibeam/ for current information regarding these surveys).
Most observations for the shallow survey were completed by 1997 September 4, although some
regions were re-scanned as recently as 1999 August 28, because of earlier pointing problems in a
few elds.
The footprint of the multibeam receiver on the sky is  1:7 ô , so that each scan maps out an
8 ô   1:7 ô strip of longitude. To obtain full coverage of the southern ZOA, 34 scans were made
between Galactic latitudes 5 ô and +5 ô at each of 23 separate central longitudes from 216 ô to
32 ô . The observing parameters and the area mapped is summarized in Table 1. In total 782
scans, or  104 hrs of data, were obtained for the 1840 deg 2 comprising the survey region. This
corresponds to an integration time, when integrated over all 13 beams, of 200 s beam 1 , where the
beam size, after gridding, has been taken to be 15: 0 5. (The full-sensitivity southern ZOA survey
will comprise 425 scans at each longitude, or approximately 1300 hrs of integration time).
The average system temperature of the multibeam receiver during the observations was  25
K. The average rms noise after Hanning smoothing and away from strong continuum and line
sources was 15 mJy beam 1 . The velocity range of the observations was 1200 to 12700 km s 1 .
The channel spacing was 13.2 km s 1 and the resolution, after Hanning smoothing, was 27.0 km
s 1 .

{ 4 {
The spectral data were bandpass-corrected, smoothed and Doppler-corrected using aips++
LiveData (Barnes 1998). For each beam and polarization, a template bandpass was calculated
by taking the median of the surrounding data with
` = 2 ô and
t = 120 s. The spectral data
were then gridded into 23 cubes, each of size 10 ô in longitude by 8 ô in latitude with a pixel size of
4 0 . Each output pixel consists of the median of approximately 30 independent (5 s) spectra which
lie within a radius of 6 0 of the center of the pixel. The use of the median statistic successfully
removes the eect of outlyers, so that interference and bad data were rejected with good eôciency
without manual editing of all spectra (which number about 2  10 6 for the shallow survey). For
more details, see Barnes et al. (2000).
3. Search Method and Prole Parametrization
The cubes were Hanning smoothed, and each of the 23 smoothed data cubes was searched
by eye using the visualization tool karma kview (Gooch 1995). (Experiments with automatic
galaxy detection algorithms have failed to date in the complicated ZOA, mainly due to baseline
instabilities resulting from the presence of strong Galactic continuum sources. The eye/brain
system is still far more eective for nding the H I signals). First, Right Ascension { velocity
planes were examined, and candidates noted. The selection criterion was a minimum peak ux
density of  75 mJy (5), with emission extended over two or more channels, or a minimum ux
integral of  4 Jy km s 1 . The candidates were then checked at the corresponding positions in
Right Ascension { declination planes. Candidates which were created by interference or increased
noise at the edges of elds were culled. Finally, the one-dimensional prole, ux density versus
velocity, was created for each source, and its shape was checked for good sense, since H I galaxies
tend to have 2-horned, at-topped, or Gaussian proles.
To measure central positions and ux integrals, a zeroth moment map was rst made by
integrating the cubes in the full velocity range occupied by each galaxy. For most galaxies, which
were unresolved, a Gaussian with the same FWHP diameter as the gridded telescope beam (15: 0 5)
and a DC oset were simultaneously tted to each zeroth moment map. Five galaxies were found
to be signicantly extended, and were tted with Gaussians of arbitrary width. The positional
accuracy is 2 0 -3 0 , depending on the S/N ratio, and the ux integral uncertainty is  20%.
Using the best-t position, spectra were then extracted from the cubes using the miriad
task mbspect (Sault, Teuben, & Wright 1995). For the unresolved galaxies, this spectrum is a
weighted average, with the weight dependent on the distance of each pixel from the tted position.
For resolved galaxies, the spectrum is spatially integrated across the galaxy. Velocity widths were
then measured at the 20% and 50% levels (W 20 and W 50 ), relative to the peak signal, using a
width-maximizing algorithm (Lewis 1983). In order to correct for the relatively coarse velocity
resolution (27 km s 1 ) of the Hanning-smoothed spectra, downward corrections of 21 km s 1 and
14 km s 1 were applied to W 20 and W 50 , respectively. A central velocity was also measured from
the 50% values. All velocities quoted are in the optical (cz) convention.

{ 5 {
4. The Catalog
The shallow survey detected 110 galaxies, whose H I parameters are listed in Table 2, and
whose proles are shown in Figure 1. In Table 2, columns contain the following information:
Column 1a: Source name;
Column 1b: Indicates if the galaxy has an optical or IR counterpart within 6 arcmin listed in
the NASA/IPAC Extragalactic Database (NED). If the entry is followed by a colon, there is no
redshift given in NED for the object, or, for IRAS 13413-6525 (HIZSS 083) and ESO 223-G012
(HIZSS 095), the HI redshift is just outside of the uncertainty indicated in NED;
Columns 2a & 2b: Equatorial coordinates (J2000) of the tted position;
Columns 3a & 3b: Galactic coordinates;
Column 4: HI ux integral;
Column 5: Heliocentric velocity (cz), the midpoint at 50% of the prole's peak ux density;
Columns 6 & 7: Velocity width at 50% of peak, and at 20% of peak ux density;
Column 8: Distance to the galaxy correcting the velocity to the Local Group frame, and
taking H 0 to be 75 km s 1 Mpc 1 ;
Column 9: Logarithm of the H I mass;
Column 10: Foreground extinction AB estimated from the IRAS/DIRBE maps of Schlegel,
Finkbeiner, & Davis (1998).
4.1. Completeness and Reliability
Of these 110 galaxies, 29 have optical counterparts listed in NED with matching redshifts.
Two more have counterparts in NED with redshifts just outside the quoted accuracy. A further
12 have a cataloged galaxy within 6 arcmin of the HI position, but with no redshift information.
The extinction at the positions of each galaxy was estimated from the DIRBE/IRAS maps of
Schlegel, Finkbeiner, & Davis (1998). Note that these maps are not calibrated this close to the
Galactic plane, so extinction measurements are somewhat uncertain. However, as expected, the
extinction is measured to be higher at the positions of the uncataloged galaxies: the median AB
for the cataloged galaxies is 2.9 mag, versus 5.7 at the positions of the uncataloged objects.
An intermediate-depth survey conducted with the multibeam system in a similar way, but
with four scans compared to the two discussed here, of the region 308 ô  `  332 ô ; jbj  5 ô ,
detected 42 galaxies (Juraszek et al. 2000). The intermediate-depth cubes and the shallow
survey cubes were searched independently. All 24 of the shallow survey galaxies in this longitude
range were recovered by Juraszek et al. , as they should have been, owing to their
p
2 improved

{ 6 {

{ 7 {

{ 8 {

{ 9 {
Fig. 1.| H I proles for the 110 shallow survey detections. Baseline excursions near 0 km s 1 and
2650 km s 1 for HIZSS 016, 017, 021, 025, 026, 030, 046, 076, 077, 078, 086, 094, and 102 are due
to Galactic H I and narrowband interference, respectively.

{ 10 {
sensitivity. Of the 18 other galaxies found by this deeper survey, 14 fell well below the selection
criteria of the shallow survey. There were four, however, which Juraszek et al. determined to have
peak uxes just at or above the shallow survey ux density cuto (J1414-62, J1417-55, J1526-51,
and J1612-56; cf. Fig 2. in Juraszek et al. ). Two of these, J1414-62 and J1612-56, were noted
as possible detections in the course of examining the shallow survey cubes, but it was felt they
were not quite secure enough for inclusion in the present catalog, the philosophy being that false
detections are extremely undesirable. The other two objects were missed. One, J1417-55, while
determined to be a broad-proled galaxy in the intermediate-depth survey, was not recognized as
a galaxy by the present work, since only one horn of the prole exceeds 75 mJy, and so appears
as a random spike, too narrow for inclusion in this sample. The other, J1526-51, peaks above 100
mJy in the intermediate-depth survey, but has a linewidth of only W 50 = 21 km s 1 , and did not
satisfy the condition of appearing in at least two channels. Thus the stated selection criteria of
the shallow survey are consistent with the results of the intermediate-depth survey in this region.
As a check on the accuracy of the measured parameters, the 21-cm properties of HIZSS 005
(IRAS 07112-0746), HIZSS 008 (IRAS 07232-2422), HIZSS 018 (IRAS 07395-2224), HIZSS 024
(ESO 493-G016), HIZSS 027 (ESO 430-G001), HIZSS 028 (ESO 561-G002), HIZSS 029 (ESO
494-G007), HIZSS 032 (ESO 494-G026), HIZSS 034 (ESO 430-G020), HIZSS 036 (ESO 430-G026),
HIZSS 037 (AM 0813-284), HIZSS 038 (ESO 430-G030), HIZSS 039 (NGC 2559), HIZSS 040
(ESO 431-G001), HIZSS 041 (UGCA 137), and HIZSS 044 (ESO 370-G015) were compared with
values found in the literature (Garcia et al. 1994, Huchtmeier & Richter 1986, Kraan-Korteweg
& Huchtmeier 1992, Staveley-Smith & Davies 1987, 1988, Takata et al. 1994, and Theureau et
al. 1998). There is excellent agreement amongst measurements of V hel , W 20 , and W 50 , typically
within a few km s 1 and only rarely diering by more than the velocity resolution. There is more
signicant scatter amongst H I ux integral measurements, re ecting the measurement uncertainty
of the shallow survey ( 20%) and in literature values. The HIZSS ux integrals are neither
systematically higher nor lower than previously published values.

{ 11 {
Table 1. Shallow survey parameters
Parameter Value
Galactic longitude 212 ô < ` < 36 ô
Galactic latitude 5 ô < b < 5 ô
Velocity coverage 1200 < cz < 12700 km s 1
Telescope FWHP resolution 14: 0 3
FWHP resolution in cube 15: 0 5
Integration time per beam 200 s
RMS noise a 15 mJy beam 1
Velocity resolution a (FWHP) 27.0 km s 1
Approximate ux density limit 75 mJy beam 1
a After Hanning smoothing.

{ 12 {
Table 2. Galaxy Parameters from HI Parkes Multibeam Observations
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
HIZSS 001 06 57 57 218.42 19.2 2720 98 145 33.8 9.7 5.5
IRAS 06555-0516 05 20 04 0.99
HIZSS 002 06 59 24 215.18 16.7 1736 147 173 20.8 9.2 3.3
CGMW 1-0476: 01 30 15 1.08
HIZSS 003 07 00 26 217.70 32.1 299 55 85 1.5 7.3 4.7
{ 04 12 17 0.08
HIZSS 004 07 09 18 219.80 20.4 1725 267 297 20.4 9.3 2.0
IRAS 07071-0520 05 25 54 1.48
HIZSS 005 07 13 33 222.45 12.1 2470 62 83 30.2 9.4 2.7
IRAS 07112-0746 07 51 51 1.29
HIZSS 006 07 18 16 224.07 12.0 915 41 72 9.4 8.4 1.9
{ 09 04 43 1.76
HIZSS 007 07 24 54 225.35 45.7 2457 168 193 29.9 10.0 1.5
NGC 2377 09 39 51 2.93
HIZSS 008 07 25 14 238.45 56.3 805 126 222 7.3 8.9 6.1
IRAS 07232-2422 24 28 25 4.01
HIZSS 009 07 25 47 232.70 11.3 2756 92 121 33.6 9.5 6.1
IRAS 07235-1747: 17 53 14 0.78
CGMW 1-0879:
HIZSS 010 07 26 38 225.17 5.1 2435 27 43 29.6 9.0 1.4
ZOAG G225.17+03.49: 09 13 24 3.51
HIZSS 011 07 27 39 238.25 14.3 4404 371 423 55.3 10.0 5.3
CGMW 2-0889: 23 57 17 3.28
HIZSS 012 07 30 08 236.80 83.7 776 264 284 7.0 9.0 7.9
{ 22 00 11 1.84
HIZSS 013 07 33 10 242.99 8.6 2089 60 127 24.3 9.1 2.2
CGMW 2-0978: 28 39 41 4.43
HIZSS 014 07 36 09 235.25 3.4 785 41 68 7.2 7.6 5.7
{ 19 27 23 0.62
HIZSS 015 07 38 02 233.29 14.5 3157 291 313 38.9 9.7 2.8
IRAS 07357-1651 16 57 04 2.23
HIZSS 016 07 38 55 241.47 11.5 2957 146 237 35.9 9.5 3.7
CGMW 2-1059: 26 13 12 2.13
CGMW 2-1056:
HIZSS 017 07 40 05 240.27 12.3 3062 229 274 37.4 9.6 3.4
IRAS 07377-2435: 24 41 40 1.15

{ 13 {
Table 2|Continued
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
HIZSS 018 07 41 47 238.56 29.7 3073 451 472 37.6 10.0 2.9
IRAS 07395-2224 22 30 47 0.26
HIZSS 019 07 42 34 249.19 24.9 2897 191 233 34.9 9.9 6.1
{ 34 37 11 5.57
HIZSS 020 07 42 48 246.89 26.0 2099 289 305 24.3 9.6 3.5
CGMW 2-1147: 31 57 39 4.22
HIZSS 021 07 46 06 244.17 25.4 491 72 95 2.9 7.7 4.3
{ 28 25 35 1.84
HIZSS 022 07 46 57 242.46 37.5 884 133 152 8.2 8.8 2.8
{ 26 20 01 0.63
HIZSS 023 07 47 21 238.44 7.3 6971 82 148 89.5 10.1 2.6
CGMW 2-1245 21 37 34 1.82
HIZSS 024 07 48 39 242.56 36.2 2642 225 405 31.7 9.9 2.9
ESO 493-G016 26 13 41 0.25
HIZSS 025 07 49 38 250.84 11.9 2861 41 70 34.4 9.5 6.3
{ 35 41 28 4.84
HIZSS 026 07 53 45 245.66 17.8 2463 180 221 29.2 9.6 3.9
IRAS 07517-2903: 29 10 03 0.78
HIZSS 027 07 55 10 244.96 48.5 1692 246 276 18.9 9.6 3.7
ESO 430-G001 28 09 17 0.01
HIZSS 028 07 55 24 239.15 36.6 938 149 171 9.1 8.9 1.5
ESO 561-G002 21 20 25 3.58
HIZSS 029 07 56 51 242.36 28.9 1556 276 288 17.2 9.3 1.4
ESO 494-G007 24 53 15 2.03
HIZSS 030 08 01 44 246.50 9.3 2764 215 225 33.2 9.4 4.1
{ 29 05 05 0.76
HIZSS 031 08 05 22 245.46 30.4 1024 24 57 10.0 8.9 1.6
{ 27 21 13 2.35
HIZSS 032 08 06 12 245.70 197.4 961 228 264 9.2 9.6 1.8
ESO 494-G026 27 31 16 2.42
HIZSS 033 08 07 02 254.42 4.6 862 108 138 7.6 7.8 5.7
{ 37 44 47 2.93
HIZSS 034 08 07 09 246.24 12.8 1022 147 173 10.0 8.5 2.0
ESO 430-G020 28 01 19 2.33

{ 14 {
Table 2|Continued
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
HIZSS 035 08 09 58 258.05 11.3 1998 281 307 22.7 9.1 5.2
{ 41 41 30 4.59
HIZSS 036 08 14 45 249.93 13.4 1660 198 230 18.4 9.0 2.4
ESO 430-G026 31 20 54 1.89
HIZSS 037 08 15 55 248.00 9.3 1705 135 150 19.0 8.9 1.7
AM 0813-284 28 51 25 3.49
HIZSS 038 08 16 31 247.43 14.7 1488 123 149 16.2 9.0 1.5
ESO 430-G030 28 05 44 4.02
HIZSS 039 08 17 12 246.97 28.6 1548 353 414 17.0 9.3 0.9
NGC 2559 27 26 06 4.51
HIZSS 040 08 17 41 248.95 11.2 1653 147 165 18.3 8.9 1.4
ESO 431-G001 29 44 34 3.31
HIZSS 041 08 17 43 249.26 47.2 1659 174 206 18.4 9.6 1.7
UGCA 137 30 06 54 3.11
HIZSS 042 08 20 57 251.92 4.8 1719 68 80 19.1 8.6 1.7
{ 32 51 49 2.13
HIZSS 043 08 26 28 261.93 41.6 1029 183 314 9.8 9.0 6.5
{ 44 19 23 3.56
HIZSS 044 08 28 38 256.35 18.6 5393 448 533 68.0 10.3 3.7
ESO 370-G015 37 10 30 0.93
HIZSS 045 08 34 12 257.32 12.7 952 65 114 8.8 8.4 3.8
{ 37 33 48 1.60
HIZSS 046 08 34 41 259.45 8.4 2779 143 168 33.1 9.3 9.2
{ 40 08 38 0.13
HIZSS 047 08 55 32 269.47 7.3 1616 57 76 17.6 8.7 7.2
{ 50 01 38 3.14
HIZSS 048 08 57 25 261.50 31.8 982 297 332 9.1 8.8 3.2
ESO 314-G002: 39 16 24 4.09
HIZSS 049 08 58 04 261.46 6.3 1216 44 72 12.3 8.3 2.7
{ 39 07 29 4.28
HIZSS 050 08 58 32 266.18 17.3 2696 244 266 32.0 9.6 16.1
{ 45 15 39 0.34
HIZSS 051 09 01 53 262.72 12.2 1634 83 107 17.8 9.0 2.4
{ 40 08 28 4.17
HIZSS 052 09 03 30 263.78 7.1 5444 58 80 68.6 9.9 4.5

{ 15 {
Table 2|Continued
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
{ 41 17 13 3.64
HIZSS 053 09 17 42 274.26 20.6 944 165 196 8.6 8.6 3.6
{ 53 22 30 2.85
HIZSS 054 09 27 58 277.16 27.9 1153 122 146 11.4 8.9 3.9
{ 55 59 26 3.66
HIZSS 055 09 37 06 277.19 8.6 2741 145 195 32.6 9.3 8.4
{ 54 37 22 1.77
HIZSS 056 09 45 38 273.92 3.1 880 52 78 7.8 7.6 2.0
{ 48 07 27 4.00
HIZSS 057 09 48 01 278.40 8.1 1734 100 114 19.2 8.8 10.6
{ 54 39 25 0.77
HIZSS 058 09 49 12 274.31 20.5 1934 206 248 21.8 9.4 1.5
ESO 213-G002 48 01 00 4.47
HIZSS 059 09 49 43 279.79 30.7 1759 203 236 19.5 9.4 9.2
{ 56 32 08 2.06
HIZSS 060 09 57 14 275.89 11.7 3725 34 57 45.7 9.8 2.5
{ 48 52 26 4.63
HIZSS 061 10 04 16 282.57 15.6 3700 225 302 45.4 9.9 15.2
{ 58 33 35 2.46
HIZSS 062 10 13 48 280.05 18.8 2707 221 258 32.2 9.7 2.1
ESO 213-G009 52 18 14 3.42
HIZSS 063 10 24 59 282.80 10.1 1083 115 175 10.5 8.4 2.7
ESO 168-G002 54 47 13 2.26
HIZSS 064 10 37 24 284.40 15.8 2670 310 350 31.7 9.6 3.1
ESO 168-G009: 54 54 39 3.06
HIZSS 065 10 39 51 284.52 12.8 2757 105 127 32.9 9.5 2.8
{ 54 31 32 3.57
HIZSS 066 10 53 42 289.95 32.3 1835 249 263 20.7 9.5 3.6
{ 62 50 30 2.98
HIZSS 067 11 30 39 292.61 13.1 1841 131 152 20.9 9.1 3.8
{ 58 46 04 2.48
HIZSS 068 11 41 14 295.46 41.4 2025 171 199 23.4 9.7 7.9
{ 64 29 02 2.64
HIZSS 069 11 49 44 296.23 62.0 2114 157 312 24.6 9.9 10.5
{ 64 00 34 1.94

{ 16 {
Table 2|Continued
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
HIZSS 070 12 02 45 297.19 96.9 1540 202 224 17.0 9.8 11.2
{ 61 40 29 0.65
HIZSS 071 12 04 16 297.65 32.6 2042 167 211 23.7 9.6 24.8
{ 63 13 10 0.83
HIZSS 072 12 13 37 299.03 16.5 2144 223 262 25.1 9.4 3.7
{ 65 33 38 2.98
HIZSS 073 12 21 31 299.16 44.4 1476 176 190 16.2 9.4 5.8
{ 59 42 40 2.94
HIZSS 074 12 45 46 302.29 27.6 3917 449 473 48.9 10.2 24.6
{ 63 05 27 0.23
HIZSS 075 13 02 26 304.13 13.7 3941 68 214 49.2 9.9 12.7
{ 64 08 15 1.29
HIZSS 076 13 12 49 305.53 16.8 2317 214 238 27.6 9.5 9.8
{ 60 53 42 1.87
HIZSS 077 13 14 50 305.95 29.1 2337 131 193 27.9 9.7 4.0
WKK 2029 58 55 47 3.80
HIZSS 078 13 27 32 307.78 24.4 2915 267 326 35.7 9.9 3.5
ESO 173-G015 57 31 04 5.01
HIZSS 079 13 29 56 307.46 18.7 3694 200 235 46.1 10.0 12.5
{ 61 50 46 0.69
HIZSS 080 13 33 07 308.43 14.3 1482 107 132 16.6 9.0 3.5
{ 58 06 09 4.32
HIZSS 081 13 37 06 308.88 12.6 4124 155 220 51.9 9.9 3.8
{ 58 31 04 3.83
HIZSS 082 13 42 14 309.04 14.3 3942 284 355 49.5 9.9 12.0
{ 61 04 58 1.19
HIZSS 083 13 45 15 308.44 30.2 2789 292 359 34.1 9.9 3.9
IRAS 13413-6525: 65 39 25 3.36
HIZSS 084 13 51 44 310.72 23.8 3869 621 698 48.6 10.1 4.5
{ 58 39 44 3.30
HIZSS 085 14 07 38 312.70 4.7 3213 44 68 39.9 9.2 8.7
{ 58 43 59 2.69
HIZSS 086 14 13 27 311.36 1866.6 436 240 278 2.8 9.5 6.1
Circinus 65 19 09 3.80

{ 17 {
Table 2|Continued
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
HIZSS 087 14 19 42 314.37 16.2 3931 385 413 49.6 10.0 6.6
{ 58 09 58 2.73
HIZSS 088 14 32 07 316.92 11.4 3109 160 244 38.7 9.6 3.7
ESO 175-G009 55 29 03 4.63
HIZSS 089 14 36 12 314.48 7.6 1546 91 103 17.8 8.8 4.6
{ 63 03 58 2.57
HIZSS 090 14 52 57 319.03 19.9 3269 311 344 41.0 9.9 6.9
{ 56 46 07 2.26
HIZSS 091 14 57 07 320.64 23.9 2875 470 489 35.8 9.9 3.7
ESO 176-G006: 54 24 04 4.09
HIZSS 092 15 01 27 318.17 14.6 4433 121 153 56.4 10.0 8.4
{ 60 43 22 1.76
HIZSS 093 15 04 15 321.04 6.2 5256 62 103 67.6 9.8 6.1
{ 55 27 49 2.67
HIZSS 094 15 05 54 321.77 8.7 2942 123 151 36.8 9.4 4.2
{ 54 23 34 3.49
HIZSS 095 15 09 28 323.15 32.5 1440 349 367 16.8 9.3 3.3
ESO 223-G012: 52 33 27 4.81
HIZSS 096 15 14 36 323.58 155.4 1457 425 451 17.1 10.0 4.3
IRAS 15109-5248 53 00 55 4.02
HIZSS 097 15 32 27 324.10 58.5 1375 58 100 16.0 9.5 78.0
{ 56 01 56 0.08
HIZSS 098 15 36 51 324.36 14.6 2729 148 189 34.1 9.6 31.2
{ 56 26 19 0.61
HIZSS 099 15 40 17 328.08 6.0 5322 62 91 68.9 9.8 3.7
{ 50 51 35 3.58
HIZSS 100 15 43 10 323.66 9.6 2905 142 158 36.4 9.5 5.0
{ 58 44 24 2.96
HIZSS 101 16 05 22 326.47 18.5 2987 83 102 37.6 9.8 2.1
{ 57 51 43 4.15
HIZSS 102 16 18 34 329.31 30.3 409 50 71 3.4 7.9 2.7
{ 55 38 44 3.77
HIZSS 103 16 20 09 336.01 16.7 4586 147 225 59.5 10.1 9.4
{ 46 21 41 2.67
HIZSS 104 16 24 33 339.32 21.1 2218 143 210 28.2 9.6 4.8

{ 18 {
5. Discussion
5.1. Nearby, H I Bright Galaxies in the Southern ZOA
The shallow survey's rms noise of 15 mJy is equivalent to a 5 HI mass detection limit of
4  10 6 d 2
Mpc M (for a galaxy with the typical linewidth of 200 km s 1 ). Thus, the sensitivity
to normal spirals falls rapidly beyond about 40 Mpc, and the survey is not well suited to discuss
large-scale structure behind the southern Milky Way beyond a few tens of Mpc. The full survey
will be sensitive to spirals to a much larger redshift, 10,000 km s 1 , and will be able to address
issues such as the Great Attractor, predicted to lie at (l, b, v)  (320 ô , 0 ô , 4500 km s 1 ) (Kolatt,
Dekel, & Lahav 1995), and other features which may lie hidden (see Kraan-Korteweg & Woudt
1999 for a review of these structures, and Kraan-Korteweg & Juraszek 2000 for preliminary
analysis of multibeam full-sensitivity survey detections in the Great Attractor region). However,
the shallow survey does now complete the census of nearby, HI bright galaxies which lie at redshifts
away from Galactic HI. Sixteen of the 110 galaxies lie at redshifts less than 1000 km s 1 and are,
therefore, fairly nearby. However, all of the shallow survey galaxies have HI ux integrals an order
of magnitude or more below that of the Circinus galaxy, a nearby, massive, low-Galactic latitude
galaxy, which is cataloged here as HIZSS 086. One can estimate the dynamical importance of
each hidden galaxy without knowledge of its inclination or precise distance by realizing that
if the galaxies in the catalog have similar M HI / M total , the gravitational force on the Milky
Way due to one of these galaxies is proportional to its HI ux integral. The closest rival in the
catalog to Circinus is ESO 494-G026 (Lauberts 1982), listed here as HIZSS 032. It has only about
10% of Circinus's HI ux. (Dynamical analysis of this object to estimate its total mass will be
conducted using HI synthesis data obtained with the VLA). All of the newly discovered galaxies
have even lower HI ux integrals. No single, previously unknown, dynamically important HI
galaxy was found. Five of the 110 galaxies are extended objects at the multibeam resolution,
and of these, three were previously cataloged: Circinus, ESO 494-G026, and IRAS 15109-5248.
21-cm follow-up synthesis mapping has been done for IRAS 15109-5248 and the two uncataloged,
extended objects, HIZSS 097 and HIZSS 102 by Staveley-Smith et al. (1998). Rotation curve
analysis indicates the IRAS galaxy is a massive disk system, estimated M tot = 6  10 11 M . The
other two are moderate to low mass systems, which under the higher resolution scrutiny of the
synthesis observations (synthesized beam FWHM  2.2 - 4.5 arcmin) were seen to break up into
apparently interacting systems of low H I column density. H I synthesis observations of all of
the shallow survey detections using the Australia Telescope Compact Array and the NRAO Very
Large Array have been completed or are planned. Identications on the currently available strips
of the southern sky NIR survey DENIS (DEep NIR southern sky Survey; Epchtein 1997) show
that many of the shallow survey sources are visible on the NIR images (Schroder, Kraan-Korteweg,
& Mamon 1999; Schroder et al. in prep.).

{ 19 {
5.2. Large-Scale Structure in the Shallow Survey
Figure 2 shows the distribution on the sky of the shallow survey detections, and galaxies
from the literature within a redshift of 4000 km s 1 . The shallow survey now lls in the southern
ZOA within about 40 Mpc for the rst time, with minimal dependence of detection-rate on
Galactic latitude (Fig. 3). The Local Void is clearly evident in the distribution of both the
optically-cataloged objects, and the shallow survey detections. It is also apparent in Figure 4, the
longitude-velocity distribution of the HI detected objects. The three shallow survey objects on
the border of the Local Void at l  30 ô all have redshifts  1500 km s 1 , consistent with their
being members of the group proposed by Roman et al. (1998). Two of these galaxies lie within
the survey boundary of the Dwingeloo Obscured Galaxies Survey, and were also detected by this
survey (Rivers, Henning, & Kraan-Korteweg 1999).
The most obvious overdensity of the low latitude galaxies apparent in Figure 2 occurs at
l  245 ô . Figure 4 reveals the overdensity is caused by two groupings of galaxies, at (l, v) 
(245 ô , 800 km s 1 ) and (l, v)  (245 ô , 1500 km s 1 ). The latter corresponds to the location
of the moderately obscured, nearby cluster in Puppis (l, b, v)  (245 ô , 0 ô , 1500 km s 1 )
(Kraan-Korteweg & Huchtmeier 1992). This overdensity of galaxies was deduced by Scharf et
al. (1992) through a spherical harmonic analysis of IRAS galaxies. The nearer group was also
recovered by Kraan-Korteweg & Huchtmeier (1992). There is no evidence of any other nearby,
unrecognized clusters of galaxies in the survey region. Except near the Galactic center where
continuum emission decreased the sensitivity of the survey somewhat, the survey was uniformly
sensitive to spirals with M HI = 2  10 9 M at 1500 km s 1 (H 0 = 75 km s 1 Mpc 1 ) across the
entire southern ZOA, so any hidden overdensities within this redshift range should have been
easily detected.
Structures at v  4000 km s 1 are not well probed by this survey, however we can see the
relative overdensity of galaxies toward the general Great Attractor region, and galaxy underdensity
behind the Puppis cluster, broadly consistent with the theoretical mass density reconstructions
of Kolatt, Dekel, & Lahav (1995) and Webster, Lahav, & Fisher (1997). The deep survey should
denitively conrm or refute the predictions of these and other mass density reconstructions in
the ZOA.
5.3. H I Mass Function
To determine the number density of galaxies as a function of H I mass (the H I mass function),
the sensitivity of the survey must be carefully determined to be able to apply appropriate volume
corrections. Near strong continuum sources, galaxies which would otherwise be detected are
hidden in the increased noise. Over the search area, 212 ô  `  36 ô , jbj  5 ô , 7.7% of the data
were disturbed by strong continuum emission, and had rms noise uctuations a factor of three or
more above the quoted sensitivity of 15 mJy. In the volume correction calculations, we take the

{ 20 {
350 300 250
­40
­20
0
20
40
GALACTIC LONGITUDE
Fig. 2.| Distribution on the sky of cataloged galaxies from the LEDA database within 4000
km s 1 (small dots) and shallow survey detections (larger dots). The shallow survey search area is
delineated by the dashed rectangle.

{ 21 {
­6 ­4 ­2 0 2 4 6
0
5
10
15
20
GALACTIC LATITUDE
Fig. 3.| Number of shallow survey detections as a function of Galactic latitude.

{ 22 {
Table 2|Continued
Name R.A. l Flux Int V hel W 50 W 20 Dist log M HI AB
Opt/IR Dec b
(J2000) ô Jy km s 1 km s 1 Mpc M mag
{ 42 29 05 4.85
HIZSS 105 16 53 05 346.34 15.1 5179 75 212 68.1 10.2 6.0
{ 37 57 23 3.79
HIZSS 106 17 11 46 340.80 16.1 2185 199 213 27.8 9.5 2.9
{ 47 35 24 4.81
HIZSS 107 17 19 42 346.77 25.6 3804 66 304 49.8 10.2 11.4
{ 41 17 18 2.31
HIZSS 108 18 55 55 30.57 13.7 1582 172 184 23.1 9.2 6.0
{ 03 13 27 2.47
HIZSS 109 19 01 48 30.10 13.7 1525 120 142 22.3 9.2 3.5
{ 04 29 51 4.35
HIZSS 110 19 10 22 35.55 14.0 1503 177 193 22.4 9.2 2.9
{ +00 30 32 3.98
2000 4000 6000 8000 km/s
Fig. 4.| Distribution in Galactic longitude and redshift of the 110 shallow survey detections.

{ 23 {
survey area to be 92.3% of the area covered by the telescope.
The galaxy selection function for the shallow survey is not based simply on peak ux, but is
determined empirically to involve both total ux and linewidth in the following way: R
S dv 
W 0:7
50 > 0.3. Schneider, Spitzak, & Rosenberg (1998) nd a very similar functional form for the
completeness limit of two previous blind 21-cm surveys done at Arecibo, R
S dv  W 0:75
50 . With
this description, the maximum volume in which each galaxy could be detected is calculated. The
average value of V / V max = 0.58, is quite close to the theoretical value of 1/2 for a correctly
determined completeness. The resulting number density of H I masses with each galaxy weighted
by the inverse of its maximum detectable volume is shown in Figure 5. This H I mass function is
well t by a Schechter function (Schechter 1976) with parameters  = 1.51  0.12,   = 0.006 
0.003, and log M  = 9.7  0.10. Note that the Schechter function was not used as an a priori
assumption of the shape of the H I mass function. The low-mass slope is signicantly steeper
than the  = 1.20 suggested by Zwaan et al. (1997). The densities at the lowest mass bins are
consistent with the higher densities found by Schneider, Spitzak, & Rosenberg (1998). The main
diôculty remains small number statistics, with the three lowest mass bins of Figure 5 containing
a total of six galaxies. With the increased search volume of the HIPASS and full sensitivity ZOA
surveys, the statistical robustness of the mass function parametrization will be improved.
5.4. Predictions for the Full Sensitivity Survey
We now estimate how many galaxies should be uncovered by the full sensitivity ZOA survey,
to be completed in the year 2000. The deep survey will consist of 435 scans at each longitude,
compared with the 34 of the shallow survey. This factor of 12.5 increase in integration time will
lead to a
p
12:5 = 3.5 improvement in sensitivity. For a galaxy of a given M HI and velocity
linewidth, the distance to which it could be detected will increase by a factor of
p
3:5. Thus,
the volume increase of the deep survey over the shallow survey is about a factor of 6.5, leading
to a rough estimate of 6:5  110  700 galaxies to be detected by the deep survey. Indeed, a
portion of the deep survey is completed, and the four data cubes in the region of the supposed
Great Attractor have been inspected, and about 300 galaxy candidates noted (S. Juraszek, private
communication). Extrapolation over the full spatial extent of the survey leads to an estimate of
about 1700 galaxies. However, this region of space contains a signicant overdensity of galaxies,
and much of the nal survey volume will contain the Local Void, so the total tally may be closer
to 1000 galaxies.
Eorts are underway to develop software tools which model and remove strong continuum
sources from the data, which should decrease the eective noise even further, increasing the survey
sensitivity and the number of detected objects.

{ 24 {
Fig. 5.| H I mass function determined from the shallow survey detections. The errorbars on
the points are determined by counting statistics. The function is satisfactorily t by a Schechter
function with  = 1.51  0.12,   = 0.006  0.003, and log M  = 9.7  0.10, shown by the solid
curve. The dashed curve shows an H I mass function derived by Zwaan et al. (1997) for a smaller
H I -selected sample of galaxies.

{ 25 {
Acknowledgements
We thank the HIPASS team (PI: Rachel Webster) for assisting with the observing, and the
sta at Parkes for their support. We also acknowledge the aips++ group for the development
of the basis of the data reduction software and some of the observing software. David Barnes
contributed very useful software for the analysis of cube statistics. We are grateful to the
multibeam instrument teams, headed by Warwick Wilson, Mal Sinclair, and Trevor Bird.
This research has made use of the NASA/IPAC Extragalactic Database (NED) which
is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National
Aeronautics and Space Administration. We have also made use of the Lyon-Meudon Extragalactic
Database (LEDA), supplied by the LEDA team at the Centre de Recherche Astronomique de
Lyon, Observatoire de Lyon. The research of P.H. is supported by NSF Faculty Early Career
Development (CAREER) Program award AST 95-02268. P.H. warmly thanks the ATNF for the
hospitality and support during her sabbatical stay.
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This preprint was prepared with the AAS L A T E X macros v4.0.