Most of the processed ESPaDOnS data from semesters 2005A to 2007B are now available from the CADC. The data available from CADC are only provided in FITS format. To obtain the Libre-Esprit formatted files (plain ascii *.s files), CFHT provides a tool to perform the conversion.
The raw and processed data can be retrieved using the regular form or the newer form at CADC.
| i | spectroscopic |
| p | polarimetric |
All object files (*o.fits) are individually processed to extract the spectrum (polarimetric and "Star Only" modes) or spectra ("Star + Sky" mode), whether they were taken in spectroscopic or polarimetric mode. These spectra are saved in *i.fits files. The reduction is done once with the continuum normalized to 1, and again with the continuum not normalized. In the FITS processed files, the reduction is also done the standard way (without the 'w' option), and with the 'w' option (which cancels automatic wavelength correction from telluric lines, and is used mostly by spectroscopists).
Therefore, all *i.fits files contain 4 spectra (or 12 in the case of "Star + Sky" mode).
The spectral and polarimetric data are stored as FITS image data in 32 bit binary floating point tabular format.
FITS keywords identify the type of reduction and content of the file:
REDUCTIO= 'Intensity' / Type of reduction FILENAME / Base filename at reduction DATE / UTC Date of reduction UTIME / UTC time of reduction HSTTIME / Local time in Hawaii of reduction FILENAMO / Base filename at acquisition DATE / UTC Date of reduction UTIME / UTC time of reduction HSTTIME / Local time in Hawaii of reduction
For the "Star Only" and polarimetric data, the i.fits files have:
COL1 = 'Wavelength' / Normalized COL2 = 'Intensity' / Normalized COL3 = 'ErrorBar' / Normalized COL4 = 'Wavelength' / UnNormalized COL5 = 'Intensity' / UnNormalized COL6 = 'ErrorBar' / UnNormalized COL7 = 'Wavelength' / Normalized, no autowave correction COL8 = 'Intensity' / Normalized, no autowave correction COL9 = 'ErrorBar' / Normalized, no autowave correction COL10 = 'Wavelength' / UnNormalized, no autowave correction COL11 = 'Intensity' / UnNormalized, no autowave correction COL12 = 'ErrorBar' / UnNormalized, no autowave correction
For the "Star + Sky" data, the i.fits files have:
COL1 = 'Wavelength' / Normalized COL2 = 'Star ' / Normalized COL3 = 'Star+sky' / Normalized COL4 = 'Sky ' / Normalized COL5 = 'ErrorBar1' / Normalized COL6 = 'ErrorBar2' / Normalized COL7 = 'ErrorBar3' / Normalized COL8 = 'Wavelength' / UnNormalized COL9 = 'Star ' / UnNormalized COL10 = 'Star+sky' / UnNormalized COL11 = 'Sky ' / UnNormalized COL12 = 'ErrorBar1' / UnNormalized COL13 = 'ErrorBar2' / UnNormalized COL14 = 'ErrorBar3' / UnNormalized COL15 = 'Wavelength' / Normalized, no autowave correction COL16 = 'Star ' / Normalized, no autowave correction COL17 = 'Star+sky' / Normalized, no autowave correction COL18 = 'Sky ' / Normalized, no autowave correction COL19 = 'ErrorBar1' / Normalized, no autowave correction COL20 = 'ErrorBar2' / Normalized, no autowave correction COL21 = 'ErrorBar3' / Normalized, no autowave correction COL22 = 'Wavelength' / UnNormalized, no autowave correction COL23 = 'Star ' / UnNormalized, no autowave correction COL23 = 'Star ' / UnNormalized, no autowave correction COL24 = 'Star+sky' / UnNormalized, no autowave correction COL25 = 'Sky ' / UnNormalized, no autowave correction COL26 = 'ErrorBar1' / UnNormalized, no autowave correction COL27 = 'ErrorBar2' / UnNormalized, no autowave correction COL28 = 'ErrorBar3' / UnNormalized, no autowave correction
For the polarimetric case, sets of 4 exposures produce one *p.fits file, which again presents data reduced with the continuum normalized to 1 and not normalized, and also with and without the 'w' option. Whether the continuum is normalized or not, the Stokes parameters are always un-normalized (i.e., the column gives for example V/I * I where I is the intensity).
A FITS keyword identifies the reduction:
REDUCTIO= 'Polar ' / Type of reduction
In general, reduction is done with 4 exposures, as indicated by those keywords:
POLARSEQ= 4 / Number of images in polar sequence STARTSEQ= 1 / Start image of polar sequence
If only 2 exposures were used, the above keywords will have different values.
The p.fits files have:
COL1 = 'Wavelength' / Normalized COL2 = 'Intensity' / Normalized COL3 = 'Stokes ' / Normalized COL4 = 'CheckN1 ' / Normalized COL5 = 'CheckN2 ' / Normalized COL6 = 'ErrorBar' / Normalized COL7 = 'Wavelength' / UnNormalized COL8 = 'Intensity' / UnNormalized COL9 = 'Stokes ' / UnNormalized COL10 = 'CheckN1 ' / UnNormalized COL11 = 'CheckN2 ' / UnNormalized COL12 = 'ErrorBar' / UnNormalized COL13 = 'Wavelength' / Normalized, no autowave correction COL14 = 'Intensity' / Normalized, no autowave correction COL15 = 'Stokes ' / Normalized, no autowave correction COL16 = 'CheckN1 ' / Normalized, no autowave correction COL17 = 'CheckN2 ' / Normalized, no autowave correction COL18 = 'ErrorBar' / Normalized, no autowave correction COL19 = 'Wavelength' / UnNormalized, no autowave correction COL20 = 'Intensity' / UnNormalized, no autowave correction COL21 = 'Stokes ' / UnNormalized, no autowave correction COL22 = 'CheckN1 ' / UnNormalized, no autowave correction COL23 = 'CheckN2 ' / UnNormalized, no autowave correction COL24 = 'ErrorBar' / UnNormalized, no autowave correction
Please note the following comments:
COMMENT For Stokes Q, V, and W, keep the Stokes parameter sign as is COMMENT For Stokes U, invert the sign of the Stokes parameter
FITS keywords from the 4 raw exposures are sometimes repeated 4 times (with new names) to indicate values that change (or should not change) from one exposure to the next. For example:
FILENAME= '977289p ' / Base filename at reduction FILENAM1= '977289o ' / Base filename at acquisition FILENAM2= '977290o ' / Base filename at acquisition FILENAM3= '977291o ' / Base filename at acquisition FILENAM4= '977292o ' / Base filename at acquisition EXPTIME1= '356.000 ' / Integration time (seconds) EXPTIME2= '356.000 ' / Integration time (seconds) EXPTIME3= '356.000 ' / Integration time (seconds) EXPTIME4= '356.000 ' / Integration time (seconds) MJD-OBS1= '54544.362' / Modified Julian Date at start of obs. MJD-OBS2= '54544.367' / Modified Julian Date at start of obs. MJD-OBS3= '54544.371' / Modified Julian Date at start of obs. MJD-OBS4= '54544.376' / Modified Julian Date at start of obs. MOONALT1= '81.0000 ' / Moon altitude at start in degrees MOONALT2= '80.9000 ' / Moon altitude at start in degrees MOONALT3= '80.6000 ' / Moon altitude at start in degrees MOONALT4= '80.0000 ' / Moon altitude at start in degrees
The ascii output from Libre-ESpRIT can be obtained from the FITS files, by using the fits2txt tool from the Opera project, available here.
The files produced have the following nomenclature:
| i | intensity spectra |
| p | polarimetric spectra |
| n | continuum normalized to 1 |
| u | continuum not normalized |
| w | data reduction done with the w option |
If you have questions, please contact the ESPaDOnS data reduction
team by sending an email to upena -=at=- cfht.hawaii.edu.