TAUVEX Data Definitions
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[edit] Level 0 Data
Level 0 data is the raw data from the spacecraft. Transmitted to the ground station through a 1Mb/s channel, this data is are made of 1024 bit major frames, which consists of an 8 bit sync word followed by 24 minor frames, of 40 bits each. Smallest building block of level 0 data is the minor frame, which may contain events data or time data or system log or filler. Level 0 Data page describes it in detail.
[edit] Level 1 data
Spacecraft telemetry and level 0 data are recieved separately at the ground station. Data acquisition system will then remove filler frames from level 0 data and merge telemetry frames in to create level 1 data. TAUVEX data pipeline takes level 1 data as input. These data will be transferred to IIA periodically on DVDs.
[edit] Intermediate data products
As the pipeline process level 1 data, several intermediate products are created. These are:
- level 1a: Level 1 data converted to FITS binary tables. The binary extension tables will have the following columns: W, S, Z, VALIDITY
- level 1b: Level 1a data with the x and y pixel information of each event. Binary table will have the following columns: W, S, Z, VALIDITY, X, Y.
- level 1c: Level 1b data with data calibration information. Names of the columns in the fits extension table are: W, S, Z, VALIDITY, X, Y, CALIB.
- level 1d: Level 1c data with flat field information. Columns are the same as level 1c, but with an updated "CALIB" column.
- level 1e: Level 1d data with geometric distortion information. Names of the columns are W, S, Z, VALIDITY, X, Y, CALIB, GEOCORRX, GEOCORRY.
- level 1f: Level 1e data with astronomical coordinate information of each event. Columns are W, S, Z, VALIDITY, X, Y, CALIB, GEOCORRX, GEOCORRY, RA, DEC, GLON, GLAT.
- level 1g: Level 1f data after data registration. Coordinate columns - RA, DEC (equatorial coordinates) and GLON, GLAT (galactic coordinates) will contain more accurate values.
[edit] Level 2 data
Once the refined coordinate information is brought into the fits binary extension tables, it is ready to be converted to an image, of processed data from single scan of sky. These images are termed level 2 data. This is the final data product from the pipeline software. Level 2 data will be fits images, readable using any of the standard astronomical data processing packages.
