ESPaDOnS Processed Data

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.

Proper CFHT acknowledgment for all refereed Espadons publications based on CFHT data is as follows:

Asterisk by the author's name to refer to a footnote stating:

*Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de lŽUnivers of the Centre National de la Recherche Scientique of France, and the University of Hawaii.

Proper Libre-ESpRIT acknowledgment is as follows:

FITS format processed files (*i.fits *p.fits)

ispectroscopic
ppolarimetric

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

Libre-Esprit formatted data

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:

iintensity spectra
ppolarimetric spectra
ncontinuum normalized to 1
ucontinuum not normalized
wdata reduction done with the w option

Contact information

If you have questions, please contact the ESPaDOnS data reduction team by sending an email to upena -=at=- cfht.hawaii.edu.