The BAT team is making available several helpful files and images to aid potential Swift users in understanding the BAT capabilities.
The FITS files contain these positions expressed in BAT tangent plane coordinates (IMX = BAT_X / BAT_Z and IMY = BAT_Y / BAT_Z), sky unit vector, and RA / DEC. For conversion to sky coordinates, a spacecraft attitude of RA = 0, DEC = 0, ROLL = 0 was used. The RA and DEC are centered on zero, so there are negative right ascensions.
See the COMMENTs lines in the FITS files for more details.