Scott Daniel of the LSST project noticed two oddities in the Fortran
SLALIB. One is harmless and the other is a bug. The latter was
fixed long ago but I suspect is still in the Starlink version.
Attached are revised GPL'ed copies of the two affected subroutines
to replace the current Starlink ones.
The harmless oddity was in sla_MAPQK. In the aberration code, a
redundant normalization was applied, that had no effect on the
spherical coordinates, just a minuscule efficiency hit.
The bug was in sla_MAPQKZ, which neglected light deflection. This
would have affected the returned position by typically a few mas
for nighttime stars. And as I said earlier, it was caught years
ago.
Patrick Wallace
____________________________________________________________________
RAL Space +44-1235-531198
STFC Rutherford Appleton Laboratory
Harwell Oxford
Didcot, Oxfordshire, OX11 0QX, UK [log in to unmask]
____________________________________________________________________
----
Starlink User Support list
For list configuration, including subscribing to and unsubscribing from the list, see
https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=STARLINK
|