Calibration Plan

Standard Calibrations

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.

Additional Calibrations

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.

'Concatenation containers' should be used within p2 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 p2), 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 p2, 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.

UVES Calibration Plan

The UVES calibration plan can be found in the UVES User Manual.

Attached Calibrations

In case that the highest possible wavelength calibration or flatfielding accuracy is required (e.g. for radial-velocity studies or high S/N observations in the regime of CCD fringing) the use of attached calibrations at nighttime is possible (cf. Template Reference Guide). However, the execution time will be charged to the corresponding program. Attached ThAr calibrations for the settings 760 and 860 are NOT permitted in Service Mode, because of remnants at the positions of the heavy saturated lines.

Iodine cell flatfields

For observations with the iodine absorption cell, daytime flatfields with and without the cell are provided. 

Night time calibrations

All possible types of nighttime calibrations (spectrophotometric standards, radial-velocity standards, telluric standards, spectra templates etc.) must be specifically requested by the users. OBs for these calibrations must be supplied by the user. The time needed to execute these OBs will be charged to the user.
Note: the UVES_<mode>_obs_std templates are only to be used for flux standards. Radial velocity or telluric star observations have to be defined with the normal science templates UVES_<mode>_obs_exp.

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