TuMag - data structure description
Polarimetric Data (Nominal)
The TuMag data are provided in single *. fits four-dimensional data cubes,
with the axis ordering of WAVELENGTH, STOKES, X, Y in python.
Currently, only non-restored data are provided.
Future versions will allow for accessing non-restored and spatially restored data,
named with LV_1.0 and LV_1.1, respectively.
Spectroscopic Data (Mode 0s)
The Spestroscopic TuMag data (IDs XX_TM_XX_Mg0s_XX) are data with no polarimetric modulation
applied, only scanning through the Mg line. They are provided in single *. fits four-dimensional
data cubes, with the axis ordering of CAMERAS, WAVELENGTH, X, Y in python.
Both detector data are kept independent, not added for dual-beam as it is done in Polarimetric Data.
Currently, only non-restored data are provided. Future versions will allow for accessing non-restored and
spatially restored data, named with LV_1.0 and LV_1.1, respectively.
Snapshot High Cadence Data (Mode ss)
The Snapshot High Cadence TuMag data (IDs XX_TM_XX_Fe02_1ss_XX) are data with single snapshots
taken at 8 pm to the red of the Fe 525.02 line core, with no spectral scanning and no polarimetric modulation.
They are provided in single *. fits three-dimensional data cubes, with the axis ordering of
CAMERAS, X, Y in python. Both detector data are kept independent, not added for dual-beam
as it is done in Polarimetric Data.
Currently, only non-restored data are provided. Future versions will allow for accessing non-restored
and spatially restored data, named with LV_1.0 and LV_1.1, respectively.
Header keywords
The most relevant TuMag header keywords for all modes are listed in the table below:
| Key | Value Type | Description |
|---|---|---|
DATE_OBS |
Date Time | UTC Acquisition Time |
FW2 |
String | Spectral line (FW2 pos.) |
NACC |
Integer | Number of accumulations |
NWAVE |
Integer | Number of wavelengths |
NMODS |
Integer | Number of modulation states |
L_0 ... L_7 |
float | Wavelength P0...P7 [A] |
In a future release, also WCS header fields will be provided.
Data Access Example (Nominal modes)
Below we show a minimalistic python script to read the 4D cubes from the provided TuMag data and compose the wavelength axis in Angstrom:
from astropy.io import fits
import numpy as np
#read the data
with fits.open("/path/to/TuMag_CUBE.fits") as hdul:
hdr = hdul[0].header
data = hdul[0].data
#Compose the wavelength array for any observation mode
prefix = "L_"
matched = {}
for key in hdr.keys():
if key.startswith(prefix):
suffix = key[len(prefix):]
if suffix.isdigit():
matched[int(suffix)] = hdr[key]
wavearr = np.array(matched[i] for i in sorted(matched)])
TuMag
