The Faint Irregular Galaxies GMRT Survey ( FIGGS ) is a Giant Metrewave Radio Telescope ( GMRT ) based HI imaging survey of a systematically selected sample of extremely faint nearby dwarf irregular galaxies .
The primary goal of FIGGS is to provide a comprehensive and statistically robust characterization of the neutral inter-stellar medium properties of faint , gas rich dwarf galaxies .
The FIGGS galaxies represent the extremely low-mass end of the dwarf irregular galaxies population , with a median M { { { } _ { B } \sim - 13.0 } } and median HI mass of \sim 3 \times 10 ^ { 7 } M _ { \odot } , extending the baseline in mass and luminosity space for a comparative study of galaxy properties .
The HI data is supplemented with observations at other wavelengths .
In addition , distances accurate to \sim 10 % are available for most of the sample galaxies .
This paper gives an introduction to FIGGS , describe the GMRT observations and presents the first results from the HI observations .
From the FIGGS data we confirm the trend of increasing HI to optical diameter ratio with decreasing optical luminosity ; the median ratio of D _ { HI } /D _ { Ho } for the FIGGS sample is 2.4 .
Further , on comparing our data with aperture synthesis surveys of bright spirals , we find at best marginal evidence for a decrease in average surface density with decreasing HI mass .
To a good approximation the disks of gas rich galaxies , ranging over 3 orders of magnitude in HI mass , can be described as being drawn from a family with constant HI surface density .