Survey Of Ionized Gas Of The Galaxy, Made With The Arecibo Telescope (Siggma): Inner Galaxy Data Release

The Survey of Ionized Gas of the Galaxy, Made with the Arecibo telescope (SIGGMA) provides a fully-sampled view of the radio recombination line (RRL) emission from the portion of the Galactic plane visible by Arecibo. Observations use the Arecibo L-band Feed Array (ALFA), which has a FWHM beam size of 3 0 .4. Twelve hydrogen RRLs from H163α to H174α are located within the<br> instantaneous bandpass from 1225 MHz to 1525 MHz. We provide here cubes of average (“stacked”) RRL emission for the inner Galaxy region 32 ◦ ≤ ` ≤ 70 ◦ , |b| ≤ 1.5 ◦ , with an angular resolution of 6 0 . The stacked RRL rms at 5.1 km s⁻¹ velocity resolution is ∼ 0.65 mJy beam⁻¹ , making this the most sensitive large-scale fully-sampled RRL survey extant. We use SIGGMA data to catalogue 319 RRL detections in the direction of 244 known H ii regions, and 108 new detections in the direction of 79 HII region candidates. We identify 11 Carbon RRL emission regions, all of which are spatially coincident with known H ii regions. We detect RRL emission in the direction of 14 of the 32 supernova remnants (SNRs) found in the survey area.