The H I Parkes Zone of Avoidance Survey: The Northern Extension

We present the results of the northern extension of the H I Parkes Zone of Avoidance Survey, a blind H I survey utilizing the multibeam receiver on the Parkes 64 m telescope. In the two regions studied here, l = 36°–52° and l = 196°–212°, |b| ≤ 5°, we have detected 77 H I galaxies, 20 of which have been previously detected in H I. The survey has a median rms noise of 6.0 mJy beam^-1 and is complete to a mean flux density of 22 mJy. We have searched for multiwavelength counterparts to the 77 galaxies detected here: 19, 27, and 11 have a likely optical, 2MASS, and IRAS cataloged counterpart, respectively. A further 16 galaxies have likely visible counterparts on the Digitized Sky Survey. The detection of these 77 galaxies allows a closer inspection of the large-scale structures in these regions. We see several filaments crossing the Galactic plane, one of which appears to be the continuation of a sine-wave–like feature that can be traced across the whole southern sky. An analysis of the H I mass function suggests that the regions studied here may be underdense. One particularly noteworthy galaxy is HIZOA J0630+08 (l, b = 203°, - 09) with a velocity of 367 ± 1 km s^-1. We suggest that it belongs to the nearby Orion Group, which includes a small number of dwarf galaxies. The newly detected galaxies improve our understanding of the properties of several voids, such as the Orion, Gemini, and Canis Major voids.