2 The data

The new general HI survey of the southern sky was performed, using the 30-m IAR dish (HPBW $\sim$ 30'), at Dec  $\leq -25\hbox{$^\circ$ }$ on a 0 $.\!\!^\circ$5 $\times$ 0 $.\!\!^\circ$5 grid in galactic coordinates. The spectrometer velocity coverage was 1055 km s^-1 centered at V_LSR = 0 km s^-1, a velocity resolution of 1.27 km s^-1, with channels separated 1.05 km s^-1, and a rms noise 0.07 K (Arnal et al. [2000]). For the final survey Arnal et al. adopted a velocity range of -450 to 400 km s^-1, with channels spaced 1.03 km s^-1, in order to fit the parameters of the northern HI survey (Hartmann & Burton [1997]). For the search of HV detections, however, we used the original survey with an effective velocity range coverage of 900 km s^-1, between -450 and 450 km s^-1.

The individual profiles of the IAR survey were smoothed to a velocity resolution of 8 km s^-1 in order to have a better sensitivity (rms $\sim$ 0.015-0.020 K). This sensitivity is comparable to that of the earlier HVC surveys (Bajaja et al. [1985]; Hulsbosch & Wakker [1988]), but with a finer grid and better velocity resolution. For the search, the smoothed profiles were scanned visually to detect the presence of HI components at HV. We selected all the HV components whose brightness temperatures were greater than 0.08 K and whose absolute radial velocity in the LSR system, V_LSR, were greater than 80 km s^-1. About 200 of the weakest isolated components, were reobserved in order to confirm them.

During the search of the HV material we found many HV components at low galactic latitudes. However, when we look for them in the b vs. V_LSR diagrams, in the latitude range -10$^\circ$$\leq$ b $\leq$ 10$^\circ$, we found that most of them were directly connected with features belonging to the galactic spiral structure at the same velocity range. They were eliminated from the final database. Gas identified as belonging to the southern galaxies listed in Table 1 was also not included in the database. These galaxies were obtained from Paturel ([1996]). The galaxies quoted by Côté et al. ([1997]) and Mateo ([1998]) were also checked for any matching with our detections.

 

 

Table 1: Identified galaxies

$l(\hbox{$^\circ$ })$	$b(\hbox{$^\circ$ })$	VLSR	Name
262.10	23.07	441	NGC 3109
273.08	-70.29	364	ESO 245-5
273.28	13.78	270	LEDA0100728
299.20	-79.42	178	NGC 300
328.55	17.85	320	IC 4662
332.67	-76.74	119	NGC 55
343.92	-50.19	121	IC 5152