What is a FITS data structure template ?
In preparation for the INTEGRAL gamma-ray satellite, the ISDC
developed the concept of data structure templates to define
the format of all data from INTEGRAL. Data structure
templates are text (ASCII) files defining the exact structure
of a set of FITS files and that can be used with a simple
command to create corresponding empty FITS files. A template
is analog to the plan to construct a shelf (an empty FITS
file) to be filled by well defined objects (a set of data).
Each template defines the format of one specific type of data
set to be stored in a distinct extension of a FITS file
For INTEGRAL, the ISDC has defined and maintains more than
1300 different data structures that form a coherent data
model for all instruments. A similar approach was also used
for the ISDC development of the Level 1 data processing for
the Low-Frequency Instrument (LFI) of the Planck satellite.
The same scheme is now also used to define the FITS data
format for the CTA project.
Basicly, there are only three distinct types of data
structures. Data can either be organized in a table with a
series of data columns or an image or a set of images forming
a data cube. A third type of data structure are indices
grouping together identical or different data structures in a
single FITS file. The actual data for any kind of data
structures is always complemented by metadata (FITS keywords)
defining the context of the data acquisition (e.g. instrument
configuration, date of observation, energy bands, etc.).
Please use the
wiki page to discuss these templates.
Science Products - Templates
Name |
Description |
Version |
|
Sky image (intensity, variance, significance, exposure,...) for given time interval (or phase bins) and energy band |
|
|
List of detected sources |
|
|
Source spectrum for a given time interval |
|
|
Source lightcurve in a given energy band |
|
Parameterized Events - Templates
Name |
Description |
Version |
|
Parameters (e.g. Hillas or physical models of the showers) characterizing the images of the air showers in each telescope for each event. |
|
Calibrated Data - Templates
Name |
Description |
Version |
|
Images of the air showers in each telescope for each triggered event |
|
|
Calibrated telescope housekeeping information |
|
Calibrated Auxiliary Data - Templates
Name |
Description |
Version |
|
Reconstructed telescope pointing information |
|
|
Calibrated atmospheric transparency |
|
|
Calibrated weather conditions |
|
|
Hardware configuration |
|
|
Hardware failure information |
|
|
Calibrated timing information |
|
|
Proposal information |
|
|
Scheduling information |
|
|
System stability information (e.g. trigger rate fluctuations) |
|
Raw Data - Templates
Name |
Description |
Version |
|
Raw pixel-by-pixel information (signal intensity in photo-electrons and pulse evolution) data for each of the triggered events as recorded by the camera pixels |
|
|
Raw telescope trigger information |
|
|
Raw telescope pointing information |
|
|
Raw telescope housekeeping information (e.g. drive information) |
|
|
Raw atmospheric monitoring information |
|
|
Raw weather conditions monitoring information |
|
|
Raw hardware (telescope, camera) configuration information |
|
|
Raw absolute timing information |
|
|
Raw TBD calibration information |
|
|
Log book, exposure and observation report |
|
Monte Carlo - Templates
Name |
Description |
Version |
|
TBD library of Monte Carlo simulated atmospheric showers |
|
|
TBD library of telescope simulator parameters |
|
Calibration Information - Templates
Name |
Description |
Version |
|
Atmospheric extinction calibration |
|
|
Site conditions (temperature, humidity) calibration |
|
|
Optical source efficiency (muon emissivity) calibration |
|
|
Reflectivity of mirrors calibration |
|
|
Quantum efficiency of the detectors versus wavelength. |
|
|
Detector amplification calibration |
|
|
Electronic gain calibration for each amplification |
|
|
Electronic threshold calibration |
|
|
Dead time calibration |
|
|
Pixel timing delay calibration |
|
|
Telescope timing synchronisation delay calibration |
|
|
Absolute timing calibration |
|
|
Telescope mirrors alignment, structure deformation and stability calibration |
|
|
Telescope field of view and uniformity calibration |
|
|
Trigger system homogeneity across the field of view |
|
Examples: HEGRA Templates
These data structures are already in use to process HEGRA data at ISDC
Name |
Description |
Version |
HEGR-EVTS-ALL |
List of calibrated HEGRA events |
1.0.4 |
HEGR-SKY.-IMA |
Contains the HEGRA sky image obtained from one or several runs |
1.0.5 |
HEGR-SKY.-IMA-IDX |
Index of all HEGRA-IMAGE data structures in one FITS file |
1.0.4 |
HEGR-EVTS-LCR |
Contains the HEGRA light-curve obtained from one or several runs |
1.0.5 |
HEGR-EVTS-LCR-IDX |
Index of all HEGRA-LIGHTCURVE data structures in one FITS file |
1.0 |
|