VizieR Online Data Catalog: HI 21-cm absorption survey of QSO-galaxy pairs (Dutta+, 2017)
Abstract
At first we constructed a parent sample of QGPs using the Sloan Digital Sky Survey (SDSS; York et al., 2000AJ....120.1579Y) and the Faint Images of the Radio Sky at Twenty-Centimetres (FIRST; White et al. 1997, Cat. VIII/92) data bases. To do this we cross-matched SDSS-Data Release 9 (DR9) galaxies with photometric redshift, zphot<=0.4, and FIRST radio sources with peak flux density at 1.4GHz>=50mJy within a 40-arcsec search radius.
We obtained the optical spectra of seven galaxies in our sample using the Robert Stobie Spectrograph (RSS) on SALT in long-slit mode, under the programmes 2013-2-IUCAA-001, 2014-1-IUCAA-001, 2014-2-SCI-017 (PI: Dutta). The observations were carried out with a 1.5arcsec slit and the PG0900 grating (resolution of ~5Å at 5000Å). Of the 55 sources that were searched for HI 21-cm absorption by us, 50 were observed with the GMRT, two with the VLA, two with the WSRT, and one was observed with both the GMRT and the WSRT. The GMRT observations were carried out using the L-band receiver. Prior to 2011, the sources were observed using the 2MHz baseband bandwidth split into 128 channels (spectral resolution ~4km/s/channel; velocity coverage ~500km/s). The later observations were carried out using the 4.17MHz baseband bandwidth split into 512 frequency channels (spectral resolution ~2km/s/channel; velocity coverage ~1000km/s). The VLA observations (Proposal ID: 15A-176) were carried out in A-configuration (maximum baseline of 36.4km) using a single 8MHz sub-band in dual polarization split into 4096 channels (spectral resolution ~0.5km/s per channel; velocity coverage ~2000km/s). In the case of WSRT observations, a total bandwidth of 10MHz split into 2048 spectral channels was used to acquire data in the dual polarization mode. This corresponds to a total bandwidth of ~2400km/s and a channel width of ~1.2km/s before Hanning smoothing. (5 data files).- Publication:
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VizieR Online Data Catalog
- Pub Date:
- June 2018
- Bibcode:
- 2018yCat..74650588D
- Keywords:
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- QSOs;
- Galaxies;
- H I data;
- Redshifts