Table 2
OIFITS main header keywords.
| Keyword | Type | Req? | Description | Example |
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| SIMPLE | T | yes | Standard FITS format | |
| BITPIX | %d | yes | Number of bits per data pixel | |
| NAXIS | %d | yes | Number of data axes1 | 0 |
| EXTEND | T | yes | Extensions may be present | |
| ORIGIN | %s | yes | Institution responsible for file creation | ESO |
| DATE | %s | yes | Date the HDU was written | 2015-01-13T16:12:56.57 |
| DATE-OBS | %s | yes | Start date of observation | 2014-10-15T18:33:26.06 |
| CONTENT | %s | yes | Must contain only the string “OIFITS2”2 | OIFITS2 |
| AUTHOR | %s | no | As defined in FITS norm | |
| DATASUM | %s | no | HDU datasum6 | |
| CHECKSUM | %s | no | HDU checksum6 | |
| Keywords set to “MULTI” for heterogenous content of the OIFITS (see text) | ||||
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| TELESCOP | %s | yes | A generic identification of the ARRAY3 | CHARA |
| INSTRUME | %s | yes | A generic identification of the instrument3 | VEGA |
| OBSERVER | %s | yes | Who acquired the data3 | S.M.Eisenstein |
| OBJECT | %s | yes | Object Identifier3 | HD123456 |
| INSMODE | %s | yes | Instrument mode3 | Low_JHK |
| REFERENC | %s | no | Bibliographic reference3 | 2001PASP..112.1133P |
| PROG_ID | %s | no | Program ID3 | 094.A-1234 |
| PROCSOFT | %s | no | Versioned Data Reduction Software3,4 | pndrs 2.6 |
| OBSTECH | %s | no | Technique of observation3,5 | SCAN, ABCD-PH, PH_REF... |
| Suggested supplementary keywords for “atomic” observations (see text) | ||||
|
|
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| RA | %f | no | Target Right Ascension at mean EQUINOX (deg) | |
| DEC | %f | no | Target Declination at mean EQUINOX (deg) | |
| EQUINOX | %.1f | no | Standard FK5 (years) | 2000.0 |
| RADECSYS | %s | no | Coordinate reference frame | FK5 |
| SPECSYS | %s | no | Reference frame for spectral coord. | TOPOCENTR |
| TEXPTIME | %f | no | Maximum elapsed time for data point (s) | |
| MJD-OBS | %.8f | no | Start of observations (MJD) | |
| MJD-END | %.8f | no | End of observations (MJD) | |
| BASE_MIN | %f | no | Minimum projected baseline length (m) | 16.01 |
| BASE_MAX | %f | no | Maximum projected baseline length (m) | 100.12 |
| WAVELMIN | %f | no | Minimum wavelength (nm) | 1200 |
| WAVELMAX | %f | no | Maximum wavelength (nm) | 1600 |
| NUM_CHAN | %d | no | Total number of spectral channels | 32 |
| SPEC_RES | %f | no | Reference spectral resolution (λ/ Δλ) | 30 |
| VIS2ERR | %f | no | Representative V2 error (%) | 5 |
| VISPHERR | %f | no | Representative Diff. Vis. Phase error (deg) | 1 |
| T3PHIERR | %f | no | Representative Closure Phase error (deg) | 1 |
Notes. Keywords in bold face are standard FITS keywords. The type column gives the format, where %s is string, %d is an integer number and %.xf is a real value with x decimal digits. The third column indicates whether the keyword is required or not.
These are bookkeeping keywords. Some of them can be inferred from the headers of the tables contained in the OIFITS file. If the file is of “atomic” type (see text), all these keywords must be filled up by the relevant value. If the OIFITS acts as a container for heterogenous data and thus more than one value of the keyword would be needed, use “MULTI”.
See Sect. 4.
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