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.

KMOS Calibration Plan

The KMOS instrument is calibrated by the Science Operations staff in the morning after the science observations. All instrument setups used in the science observations are calibrated automatically.

The standard calibration products provided by the Observatory are given in the KMOS User Manual.


Telluric standard star observations in the 3-IFU mode (one per detector) are taken within 2 hours by the Observatory (in case the user has not provided his/her own standard star observations). The correction for the airmass is done by the ESO pipeline. The accuracy of such a correction is reported in the KMOS User Manual. Users who required a higher accuracy, must provide the OB of the telluric, ideally concatenated to the science OB.

If a standard star observation for all 24 IFUs is desired, i.e. with the arm pattern of the science configuration (scipatt mode), this is charged to the user. Note that in this case the coordinates of the standard star have to be entered manually in the target section of the OB after the KARMA setup file has been inserted.

Starting in P112, the observatory will only provide a telluric star (A0 or earlier spectral type) taken in the evening twilight at an average airmass. This, combined with the use of molecfit in the reduction of the data with the ESO pipeline, should provide an accurate telluric absorption correction for most of the scientific cases. 

Spectro-photometric standard

Spectro-photometric standard star observations, either in the 24-IFU or the 3-IFU mode (one per detector), are taken on demand, i.e. they are charged to the user. The user has to provide the Vega magnitude of the star in the observed band.

Nighttime flats and arcs

Attached nighttime flats and arc exposures are possible, but are charged to the user.

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