Surf understands a number of different coordinate frames and uses two letter codes3 (as used by the JCMT) to describe them. The following are available:
| RB | FK4 B1950 |
| RJ | FK5 J2000 |
| RD | Apparent RA/Dec, current epoch |
| GA | Galactic coordinates (J2000) |
| NA | Left hand Nasmyth coordinates |
| AZ | Az/El offsets |
| PLANET | JCMT input coordinate frame for moving source |
| PL | SURF output coordinate for offsets from tracking centre |
These coordinate frames are used to specify the tracking centre (CENT_CRD), the coordinate frame of the
chop (CHOP_CRD), the coordinate frame of any offsets (LOCL_CRD) and the coordinate frame of the
sampling (SAM_CRDS) (eg jiggle coordinate frame or scan coordinate frame)
SURF currently assumes that the instrument is on the left hand Nasmyth platform.
3with the exception of PLANET frame