We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey ( BASS ) .
We analyze optical spectra of the majority of AGN ( 77 % , 641/836 ) detected based on their 14–195 keV emission in the 70-month Swift BAT all-sky catalog .
This includes redshift determination , absorption and emission line measurements , and black hole mass and accretion rate estimates for the majority of obscured and un-obscured AGN ( 74 % , 473/641 ) with 340 measured for the first time .
With \sim 90 \% of sources at z < 0.2 , the survey represents a significant advance in the census of hard-X-ray selected AGN in the local universe .
In this first catalog paper , we describe the spectroscopic observations and datasets , and our initial spectral analysis .
The FWHM of the emission lines show broad agreement with the X-ray obscuration ( \sim 94 \% ) , such that Sy 1-1.8 have N _ { H } < 10 ^ { 21.9 } cm ^ { -2 } , and Seyfert 2 , have N _ { H } > 10 ^ { 21.9 } cm ^ { -2 } .
Seyfert 1.9 , however , show a range of column densities .
Compared to narrow line AGN in the SDSS , the X-ray selected AGN have a larger fraction of dusty host galaxies ( { H } \alpha / { H } \beta > 5 ) suggesting these types of AGN are missed in optical surveys .
Using the [ O iii ] \lambda 5007 /H \beta and [ N ii ] \lambda 6583 /H \alpha emission line diagnostic , about half of the sources are classified as Seyferts , \sim 15 \% reside in dusty galaxies that lack an H \beta detection , but for which the upper limits on line emission imply either a Seyfert or LINER , \sim 15 \% are in galaxies with weak or no emission lines despite high quality spectra , and a few percent each are LINERS , composite galaxies , HII regions , or in known beamed AGN .