Instructions
The PROGTEMP code is an integral part of describing how the instrument is configured (see
WEAVE - instrumental overview for more information). This parameter encodes the requested instrument configuration, OB length, exposure time, spectral binning, cloning requirements and probabilistic connection between these clones. Registered WASP users can also access the
PROGTEMP form on WASP, similar to the one hosted at ING for phase-1 proposal preparation.
Instrument mode and configuration
Check first what instrument modes are available in the current announcement of opportunity.
OB length
This PROGTEMP component specifies the overall OB length (inclusive of overheads). Please be aware that not all OB lengths are available.
The exception here is OB length 30 minutes options cannot be used for MOS observations.
Arm exposures
It defines how the time within the OB that you wish to observe the target is divided up, by specifying the number of exposures and exposure time within the stipulated OB length. The listed options of exposure time splits correspond to science open-shutter times (note that every exposure incur a 3-minute overhead).
It is WEAVE policy to "lock" the arms, i.e., the red and blue arms must be observed with the same exposures within an OB. It is not recommended to unlock the arms. Note that different exposure splits in the red and the blue arms will have two consequences: no dithering will be possible and OB length will increase as the observing system cannot execute different exposure splits simultaneously but one only exposure in both arms at a time. For example, requesting one exposure in the red arm, and 12 in the blue arm would cause a significant mismatch in overheads between the two arms.
Note that dithering is only possible in LIFU and mIFU modes and options for which fixed dither patterns are available are exposures 3x, 4x, 5x, and 6x.
Binning in the spectral direction
Only listed values are allowed, all other values are forbidden. As an aside, note that there is no facility to request spatial binning in WEAVE. Such a mode would compromise the spectral extraction performance and crosstalk characterisation within the L1 pipeline.
Duplicate this OB x times
This component is entirely optional – validation checks will not fail if there is no × value in the PROGTEMP. If an applicant wishes to duplicate the observations of this target, then duplication would result in the OB this target lives in being duplicated × times, or in other words, one only OB will be generated but it will be clonned × times when ingested into the observing system.
Furthermore, if PIs want to "chain" these OBs together, such that the observation of one of these clones increases the chance that the remaining OBs in this group are observed, then a "+" should be added to the end of PROGTEMP (check 'Chained?' in the form above). The "+" instructs the WEAVE scheduler to increase the (internal, programme-specific) weight of all OBs in this group. This provides a mechanism to ensure that once a series of observations are started, completion of the chain becomes a progressively higher priority above other OBs from this programme.
Please use this exposure time calculator for your signal-to-noise calculations. There is more information, including a downloadable version, at WEAVE Exposure Time Calculator.
