The data provided are from the THOR survey: 

The HI/OH/Recombination line survey of the Inner Milky Way,

a 21cm line and continuum survey conducted with the Very Large Array
(VLA). The corresponding survey paper is Beuther et al. (2016). More details
about the survey can also be found at http://www.mpia.de/thor

Associated with the publication of the overview paper, we provide the first
half of the survey data in fits format as continuum images and line data
cubes. The exact data products are described in Beuther et al. (2016, in
particular Table 2). 

Currently, only full tiles can be downloaded, but it is planed to have in the
future also smaller cutout-image options. The current tiles are always
centered on Galactic longitudes labeled in the file names. The different
data products are divided in the following substructures:

-- continuum in 6 bands between 1 and 2GHz: 
   CONT_full-resolution: native resolution
   CONT_25arcsec: 25'' resolution
   CONT_1400mhz_CD_GBT: Combined THOR plus VGPS data at 25'' resolution
                      As outlined in the paper, since the combination of
                      THOR with VGPS uses for the continuum very different
                      bandpasses (120MHz versus 1MHz), the absolute fluxes 
                      of these combined images have to be treated with caution.

-- continuum source catalogs:
   thor_continuum_catalog_all_published.fits: The full continuum catalog.
   thor_HII_fitting.fits: Continuum sources that are associated with HII
   regions and were fitted to derive the properties of the HII region, such
   as electron temperature and electron density.

-- HI: HI@21cm: THOR only with cont. (HI_VLA-C_with_continuum, native res.;
       		     	     HI_VLA-C_with_continuum_25arcsec, 25" resolution)
                         --> The combination of the pilot field (L30.50) and
                             adjacent fields was not possible due to different
                             spectral setups. Hence we do not combine the pilot
                             field with the other fields and provide them 
                             separately.
                THOR merged with VGPS continuum-subtracted, 40'' resolution
                             (HI_VLA_C_and_VGPS_without_continuum)
                         --> The HI images combined the THOR and VGPS data.
			     First, we cleaned the C-array THOR data together
       		     	     with the D-array VGPS data, and subsequently we used the feather
                             task in CASA to combine the cleand images with
       		     	     the VGPS ones. As no VGPS data exists
                             for the first two THOR tiles (l=15.00 and 16.25deg), we
                             cannot provide combined images for these regions.

-- OH_1665_1667: OH@1665MHz and OH@1667MHz 
                 native resolution and 20'' resolution

-- OH_1612: OH@1612MHz 
                 native resolution and 20'' resolution

-- OH_1720: OH@1720MHz 
                 native resolution and 20''

-- RRL: stacked radio recombination line images at 40'' resolution