ISAAC calibration data like darks, lamp flats and arc frames are mostly taken as daytime calibrations. Standard stars, startrace calibrations, and illumination correction calibrations are taken during night time; imaging sky flats are taken during twilight.
On request by the user, also nighttime calibrations, only spectroscopic flats and arc frames, can be obtained as
part of the Observing Block which generates the SCIENCE data ("attached
OF RAW CALIBRATION DATA
Find information about the ISAAC data format,
spectral format and the detector here.
The following calibration data are taken as part
of the daily ISAAC calibration plan for imaging modes. The data types are identified by
the DPR TYPE keyword in the FITS headers.
typical number taken per night and setting
detector status, dark level, RON
fixed pattern noise, vignetting
standard stars for detector response
17, once a period
standard stars for photometric zeropoints
detector linearity correction
15-20, 6 times a year
The following types of calibration data exist for ISAAC spectroscopy modes:
The processing of ISAAC calibration frames requires a cascaded scheme
where the mutual dependencies of products and raw frames are respected.
The proper sequence of all these production steps is called the calibration
cascade. It is described here.
Within that cascade, all products are checked with respect to their quality
and their relationship in time. This means e.g. that a dispersion solution
is not only generated using an arbitrary quality-checked localization
solution, but that specific solution is chosen which is closest in time.
All products created by QC Garching follow the calibration cascade. On contrary, Paranal-processed science data never use the up-to-date calibration
products but standard solutions manufactured by QC Garching and possibly
several months old.
The following static calibration tables (the ones not being regularly
processed from raw calibration data) are required for ISAAC data processing:
the sky OH emission line table
the Argon emission line table
the Xenom emission line table
the photometric standard star table
the spectral energy distribution table
They come as FITS binary tables. They are part of the SM delivery
for ISAAC data.
tables can be downloaded as gzipped tar file here
[440 kB, created in September 2007].
wavelength calibration using sky OH emission lines
wavelength calibration using argon emission lines
wavelength calibration using xenon emission lines
catalog of photometric standard stars, used for photometric zeropoints and conversion function
spectral energy distributions of selected spectral types, used for flux calibration