LIFU observing, calibration
Observations with WEAVE are carried out by defining, scheduling and excuting
observing blocks (OBs).
Each OB includes one or more observations
(with or without dithering) of the science targets, and any required
night-time calibration exposures at the same pointing.
At any one time, the OB database contains a large number of OBs ready
for execution.
The OBs are executed in queue-schedued mode. At the beginning of the night,
the ING staff observer at the telescope uses the WEAVE scheduler software to
generate a queue of OBs for observing. The scheduler takes into account the
ambient or predicted seeing and transparency (provided by the observer),
the sky brightness (calculated from a model, for a given OB and time of
observation) and the relative science priority
of different OBs. The staff observer can edit or pause the queue as required
during the night, in response to changing observing conditions or any technical
problems.
Quick-look data reduction
in near real-time allows the staff observer to check the delivered
SNR and make other quality-control checks.
Calibration arc (e.g. ThArCr) and flat-field exposures are currently scheduled
automatically with each OB.
In addition, daytime calibration exposures and twilight
flats are taken as required (for the data-reduction pipeline at CASU).
The light for the arcs and flats is supplied by
a calibration unit (formerly used with AF2)
mounted at a 'broken Cassegrain' focus of the telescope.
Potential PIs requiring separate
flux-calibration observations should contact ING
for guidance.
Chris Benn, Lilian Domínguez, Cecilia Fariña
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