PTGRID (see listing in Appendix 
)
contains a grid of stars with accurately-known positions for pointing
tests. The following four catalogues are subsets of PTGRID and contain
stars which pass through the zenith. They are to be used for
setting the encoder zeropoints of the telescope (SNAFU) (section
and for measuring the seeing (section ).
Spectrophotometric Flux Standards
SPECPHOT Spectrophotometric flux standards
A description of this data is given in La Palma Technical Note 65. There is a blue loose-leaf binder on the control-room shelf entitled: `Spectral Flux Standards' which includes LPTN65, and further standards from Oke, J.B. 1990 (A. J., 99, 1621) and Massey, P. et al. 1988 (Ap. J., 328, 315).
Photometric standards
The following six catalogues contain stars from Landolt's list of equatorial standards for UBVRI photometry. There are two overlapping sets, one with photometry by D.H.P. Jones & J.E. Sinclair (from SAAO) and the other with photometry by Landolt (from KPNO; see INT Prime Focus manual for details). Users should be warned that there are differences between the two datasets in the U and B bands, as is discussed further in the .DOC files. All of the positions have, however, been checked and/or remeasured. There is a further division between stars suitable for CCD's (V > 10) and those which should only be used with photoelectric photometers.