Globular Cluster NGC 6397

Release of the spectra of the globular cluster NGC 6397 as published in Husser et al. (2016) and Kamann et al. (2016).

Provided are all the obtained spectra with a signal-to-noise ratio of five or larger, i.e. 14271 spectra in total.

NGC6397 Overview
Overview of the pointings for NGC 6397

Download

All the spectra can be downloaded here:
http://data.muse-vlt.eu/NGC6397/ngc6397.zip

The names of the directories are all formatted according to pointingXX_YYYY-MM-DD, where XX is the number of the pointing as indicated in the image above, followed by the date of the night of observation.

Spectra

The filenames of the individual spectra have the following format:
ngc6397id99999999jd7777777p4444f333.fits

  • The first seven digits give the cluster name, which is ngc6397 for all spectra.
  • The following 11 digits contain the ID of the star. The ID is the as in the catalogue of Anderson et al. (2008), AJ, 135, 2055 for stars included in the ACS catalogue. For the remaining stars, it is a 9-digit number and the first two digits indicate the pointing identifier.
  • The star ID is followed by the Julian date of the observation (14 digits). The four digits following the ‘p’ contain the fraction part. For example ‘jd2456866p4985’ corresponds to a Julian date of 2456866.4985.
  • The remaining 4 digits include a quality flag which is the sum of one or more of the following flags:
    • 0 – good spectrum
    • 1 – the spectrum includes contributions from more than one star
    • 2 – the spectrum has an estimates S/N < 10
    • 4 – the spectrum has a mean flux < 0
    • 8 – the centroid of the star is outside the observed field of view

Tellurics

Each directory in the archive also contains a file called tellurics.fits, in which the mean telluric absorption spectrum is stored as determined for all observed spectra with a signal-to-noise ratio larger than 50.

FITS Header Keywords

The following header keywords were created during the extraction of the spectra from the data cubes (with examples):

  • HIERARCH PAMPELMUSE VERSION = ‘0.18.2.0’ / The version of PampelMuse used to extract the spectra.
  • HIERARCH PAMPELMUSE REVISION = 225 / The revision of PampelMuse used to extract the spectra.
  • HIERARCH PAMPELMUSE FILENAME = ‘ngc6397_combined_p55.prm.fits’ / The filename of the results file written by PampelMuse.
  • HIERARCH PAMPELMUSE UTC = ’15-01-13 14:33:17′ / The UTC timestamp when the extraction with PampelMuse was completed.
  • HIERARCH PAMPELMUSE PASSBAND = ‘f606w   ‘ / The photometric filter used to measure magnitudes.
  • HIERARCH PAMPELMUSE SEEING = 3.715760620415648 / The average FWHM of the PSF used to extract the spectra in spaxels.
  • HIERARCH STAR ID =             19000043 / The ID of the star in the photometric reference catalogue.
  • HIERARCH STAR RA =          265.0982362 / The right ascension of the star in decimal degrees.
  • HIERARCH STAR DEC =          -53.6723864 / The declination of the star in decimal degrees.
  • HIERARCH STAR MAG =    17.42799949645996 / The magnitude of the star in the photometric filter provided in ‘HIERARCH PAMPELMUSE PASSBAND’
  • HIERARCH SPECTRUM MULTISTAR = F / A flag indicating if the extracted spectrum contains contributions from more than one star.
  • HIERARCH SPECTRUM XCUBE = 237.8492736816406 / The x-position of the star in the MUSE cube in units of spaxels.
  • HIERARCH SPECTRUM YCUBE = 43.05841827392578 / The y-position of the star in the MUSE cube in units of spaxels.
  • HIERARCH SPECTRUM INFIELD = T / A flag indicating whether the centroid of the star was inside the MUSE field of view.
  • HIERARCH SPECTRUM EDGEDIST = 19.25799554177974 / The distance of the star to the edge of the MUSE field of view in units of spaxels. Negative numbers are used for sources outside the field of view.
  • HIERARCH SPECTRUM SNRATIO = 35.05657327690547 / The signal-to-noise ratio estimated from the extracted spectrum.
  • HIERARCH SPECTRUM QLTFLAG = 0 / The quality flag of the extracted spectrum.  See filename description for details.
  • HIERARCH SPECTRUM TYPE = ‘star    ‘ / The type of extracted spectrum, always ‘star’ in this case.

In addition, the following keywords have been copied from the raw data:

  • HIERARCH OBSERVATION AIRM START /  The airmass at the start of the observations. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AIRM END  / The airmass at the end of the observations. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI FWHM START / The DIMM seeing at the start of the observations in arcseconds. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI FWHM END / The DIMM seeing at the end of the observations in arcseconds. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI PRES START / The atmospheric pressure during the observations in hPa. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI RHUM / The relative humidity during the observations. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI TAU0 / The tau point during the observations in degrees of celsius. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI TEMP / The outside temperature during the observations in degrees of celsius. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI WINDDIR / The wind direction during the observations in degrees. Copied from header of raw MUSE data.
  • HIERARCH OBSERVATION AMBI WINDSP / The windspeed during the observations in m/s. Copied from header of raw MUSE data.