Catalog Assistant Help
The PIT includes a catalog assistant tool which has been
designed to help search for
wavefront sensor stars. A search can be canceled at any time by clicking the 'Cancel' button at the bottom of of the screen.
- Select a server
and search algorithm in the Criteria section.
Different algorithms are available e.g. for peripheral wavefront
sensors (PWFS), on-instrument wavefront sensors (OIWFS) and facility adaptive
optics wavefront sensors (AOWFS). See the relevant instrument
"Performance and Use" web pages for the recommended WFS for each
instrument mode.
Guide star catalog servers are available at CDS, CADC, and ESO.
Generally you will get the best performance by selecting the
geographically closest server.
If the guide star is the same as the target, frequently the case for AO observations,
then select either the Target is NICI AO Guide Star algorithm if using NICI or the Target is AOWFS Guide Star algorithm if using Altair. - Select all
or specific science targets from the Target Selection list to have guide stars found for those objects. Individual targets may be
selected/deselected using the 'Included?' checkbox. Unselect all targets with the 'None' button.
- Activate
the search by clicking on the magnifying
glass icon.
The green LED will flash whilst the search
is in progress. You can stop the search by clicking on the stop sign
icon. The status for each target will change from pending to
complete when finished.
Upon completion the search
results for each target are listed at the bottom of the
page. The star name, coordinates, magnitude and other information are
shown for each star.
Generally the algorithm will select the brightest stars available
within acceptable magnitude limits in the WFS patrol field. Note that
the PWFS may partially vignette the widest fields (e.g. NIRI f/6) - see
the NIRI pages for more details. You can override
the algorithm, and view all potential stars from the chosen catalog
that are in the patrol field, by selecting the target and using the
'Override?' checkbox. You may then choose alternative, or additional,
stars. Be wary of stars with V magnitudes fainter than 15 (or 13 if
chopping) since these are usable only in the best conditions.
- Complete the WFS star search by clicking on the Ok
button. The selected WFS stars (name, co-ordinates and brightness) will
be added to each observation in the program information tree.
The catalog search can fail because there are no
cataloged stars available within the
WFS patrol field. If you know of suitable WFS star(s), they may be
added manually (see the
Help
with
Observations page). Some objects may have no suitable stars
and cannot be observed.
WFS stars should not be added for non-sidereal
objects or target of opportunity observations at this time.