The most commonly used observing configurations of each instrument are calibrated by means of the Observatory's Calibration Plan. Calibration Plans for each instrument and mode are described in detail in their corresponding User Manual, and their execution times are not charged to the Service Mode programmes.
Please check carefully in the User Manual whether or not the instrument configurations that you plan to use are included in the instrument's Calibration Plan. If this is not the case, you must provide additional OBs for calibration appropriate for each mode not included in the Calibration Plan. Their execution time is then charged to your time allocation.
User-supplied OBs for calibration are only executed once. You should assume that your science OBs will be executed completely independently of each other, possibly on different nights, and take into account that no user-supplied OB (for a science or a calibration target) will be executed more than once. You should submit enough OBs to cover that situation. For example, if you need to observe and flux-calibrate six targets in a filter that is not supported by the calibration plan of the instrument, you need to provide six OBs for photometric calibration to allow for the case in which each target is observed on a different night. This must be done even if the same calibration star can be used for all the science targets.
Please indicate in the User Comments fields of science OBs when a user-provided calibration must be executed contiguously.
Since P90 'concatenation containers' can be used within P2PP version 3 to link science and calibration observations that must be executed contiguously.
Please note that there are two separate kinds of calibrations in operational terms:
- Calibrations that observe a reference celestial source, like a spectrophotometric standard star or a nearly-featureless star for the measurement of telluric lines. The OBs prepared for this kind of calibration are generically considered as normal OBs (to be prepared within an "OB" in P2PP3), and their construction is the same as for other science OBs. However, depending of the instrument they use either templates whose name contains the indicator calib, or flags in the templates that indicate that the observation is intended for calibration.
- Calibrations with no celestial source associated, like flat fields taken with a flat field lamp or dark exposures. OBs for this kind of calibration should be prepared within the "CB" (Calibration Block) in P2PP, as no acquisition template needs to be specified in this case. Calibrations to be executed in daytime are the most common examples in this category.
VIRCAM Calibration Plan
The VISTA/VIRCAM calibration plan can be found in the VIRCAM/VISTA User Manual.
Each VISTA observation contains hundreds of 2MASS stars that are used for photometric calibrations. The number of standard star fields observed so far is sufficient for accurate photometric equations determination. Due to larger uncertainty in Z and Y-band for extincted regions the UKIRT standard star fields in these bands were observed once or twice per night only until all ZY VVV OBs were completed. Since the end of 2012 typically only one standard is observed in the beginning of the night. In case you need to have more standard star fields observed, please provide a short rationale, list of standard star fields to be observed, their frequency and the time necessary to do these calibrations.