| Summary: | Flux calibration file contains an average calibration model for a given camera including airmass and seeing dependencies. |
|---|---|
| Naming Convention: | fluxcalib-{CAMERA}.fits, where where {CAMERA} is
one of the spectrograph cameras (e.g. z1). |
| Regex: | fluxcalib-{brz][0-9].fits |
| File Type: | FITS, 84 KB |
The model is parameterized as
calibration_model(lambda) = average_cal(lambda) * 10^( -0.4*( (seeing-pivot_seeing)*seeing_term(lambda) + (airmass-pivot_airmass)*atm_ext(lambda) ))
calib_flux [1e-17 erg/s/cm2/Angstrom] = uncalib_flux [counts/Angstrom] / (calibration_model * exptime [s])
| Number | EXTNAME | Type | Contents |
|---|---|---|---|
| HDU0 | FLUXCALIB | IMAGE | Average flux calibration |
| HDU1 | ATERM | IMAGE | Airmass dependent term |
| HDU2 | STERM | IMAGE | Seeing dependent term |
| HDU3 | WAVELENGTH | IMAGE | Wavelength grid |
| HDU4 | ATERM_ERR | IMAGE | Uncertainty on airmass dependent term |
| HDU5 | STERM_ERR | IMAGE | Uncertainty on seeing dependent term |
EXTNAME = FLUXCALIB
Average flux calibration model such that calibrated flux = uncalibrated photons / model.
| KEY | Example Value | Type | Comment |
|---|---|---|---|
| NAXIS1 | 2380 | int | |
| BUNIT | 10**+17 cm2 count s / erg | str | i.e. (elec/A) / (1e-17 erg/s/cm2/A) |
| CHECKSUM | 2pfC2ofA2ofA2ofA | str | HDU checksum updated 2018-11-27T11:46:41 |
| DATASUM | 3135063907 | str | data unit checksum updated 2018-11-27T11:46:41 |
Data: FITS image [float32, 2380]
EXTNAME = ATERM
Atmospheric extinction term
| KEY | Example Value | Type | Comment |
|---|---|---|---|
| NAXIS1 | 2380 | int | |
| PAIRMASS | 1.132032318244172 | float | pivot airmass (airmass of average calib.) |
| CHECKSUM | Xd3dYd0bXd0bXd0b | str | HDU checksum updated 2018-11-27T11:46:41 |
| DATASUM | 1519080666 | str | data unit checksum updated 2018-11-27T11:46:41 |
Data: FITS image [float32, 2380]
EXTNAME = STERM
Seeing term
| KEY | Example Value | Type | Comment |
|---|---|---|---|
| NAXIS1 | 2380 | int | |
| PSEEING | 1.075342118740081 | float | pivot seeing (seeing of average calib.), FWHM arcsec |
| CHECKSUM | IOTaKNRTINRZINRZ | str | HDU checksum updated 2018-11-27T11:46:41 |
| DATASUM | 1211437529 | str | data unit checksum updated 2018-11-27T11:46:41 |
Data: FITS image [float32, 2380]
EXTNAME = WAVELENGTH
Wavelengths at which the flux calibration model is evaluated.
| KEY | Example Value | Type | Comment |
|---|---|---|---|
| NAXIS1 | 2380 | int | |
| BUNIT | Angstrom | str | |
| CHECKSUM | CbCQFZ9OCaAOCY9O | str | HDU checksum updated 2018-11-27T11:46:41 |
| DATASUM | 3517056679 | str | data unit checksum updated 2018-11-27T11:46:41 |
Data: FITS image [float32, 2380]
EXTNAME = ATERM_ERR
Uncertainty on atmospheric extinction term
| KEY | Example Value | Type | Comment |
|---|---|---|---|
| NAXIS1 | 2380 | int | |
| CHECKSUM | fCmKhBkHfBkHfBkH | str | HDU checksum updated 2018-11-27T11:46:41 |
| DATASUM | 984665518 | str | data unit checksum updated 2018-11-27T11:46:41 |
Data: FITS image [float32, 2380]
EXTNAME = STERM_ERR
Uncertainty on seeing dependent term
| KEY | Example Value | Type | Comment |
|---|---|---|---|
| NAXIS1 | 2380 | int | |
| CHECKSUM | LaNJNZNJLaNJLYNJ | str | HDU checksum updated 2018-11-27T11:46:41 |
| DATASUM | 803867299 | str | data unit checksum updated 2018-11-27T11:46:41 |
Data: FITS image [float32, 2380]
File produced by the desispec script desi_average_flux_calibration. Used by QuickLook and the off-line calibration.