Config File

GAMSE uses configuration files to control the input parameters and the procedures performed during the data reduction. A configuration file is a plain text file with the name of XXX.cfg. It follows the RFC 822 format and is similiar to .INI files in Microsoft Windows systems. Briefly, it consists of a series of sections led by headers like [XXX], and each section contains some entries like name: value or name=value. Comments prefixed by hash (#) or semicolons (;) symbols are supported, for example:

[data]
telescope   = Fraunhofer
instrument  = FOCES
rawdata     = rawdata   # path to raw data
statime_key = FRAME     # key of starting time of exposure in FITS header
exptime_key = EXPOSURE  # key of exposure time in FITS header
direction   = xb+

[reduce]
midproc     = midproc   # path to mid process files
report      = report    # path to reports
result      = onedspec  # path to one dimensional spectra
mode        = normal
fig_format  = png

[reduce.bias]
bias_file     = ${reduce:midproc}/bias.fits
cosmic_clip   = 10      # upper clip threshold
maxiter       = 5       # maximum iteration number

[reduce.trace]
minimum    = 8
scan_step  = 100
separation = 500:26, 1500:15
filling    = 0.3
align_deg  = 2
display    = no
degree     = 3
... ...

GAMSE includes built-in configuration files for some spectrographs. Therefore, users do not have to find these values their own. The above example is the content of the built-in configuration file for FOCES spectrograph.

Sometimes, one may want to change the values of a few entries. In these cases, users can create a new .cfg file in the working directory and write these entries together with their section names in. Only the entries in the new configuration files are overridden during the data reduction.

For example, a user-created .cfg file with:

[data]
telescope   = Fraunhofer
instrument  = FOCES
rawdata     = rawdata

[reduce]
fig_format  = pdf

will only override the value of fig_format in the reduce section in the built-in configuration files.

List of Accepted Entries

Gamse uses a set of general keywords in the config file to descrip the data formats. They are in the [data] section of the config files.

Accepted entries in [data] section
Key Type Default Value Description
telescope str Fraunhofer Name of the telescope (Fixed).
instrument str FOCES Name of the instrument (Fixed).
rawdata str rawdata Path to the rawdata.
statime_key str FRAME Key of starting time of exposure in FITS header.
exptime_key str EXPOSURE key of exposure time in FITS header.
direction str   Direction of the echelle spectrum on the CCD.

  • telescope and instrument: Name of the telescope and the instrument.

  • rawdata: Path to the folder for the raw data. It tells the software where to find the raw images. The default value is a sub-directory called rawdata in the working directory. The user may want to keep the raw data in their original places, but to use a soft link to the actual data path, instead. For example, the raw images taken on July 18, 2018, are in /data/foces/rawdata/2018/0718/, and the following command is to create a soft link called rawdata in the working directory:

    ln -s /data/foces/rawdata/2018/0718 rawdata

    Alternatively, one can use the actual data path in the configuration file:

    rawdata    = /data/foces/rawdata/2018/0718

    In this case, the soft link to the data path is not necessary anymore.

  • statime_key: Key of the starting time in the FITS header.

  • exptime_key: Key of the exposure time inf the FITS header.

  • direction: Direction of the Echelle spectrum on the CCD. A typical direction string is composed of three letters, like xb+ or yr-, where

    • The first letter indicates the axes of main-dispersion direction (either x or y).
    • The second letter, either b or r is the direction of red/blue orders. b means the blue orders locates in the smaller row (if the first letter is x) or column (if the first letter is y) numbers in the CCD. And r means the red orders vice-versa.
    • The last letter indicates whehter the wavelength is increasing (in this case, +) or descreasing (in this case, -) along the increasing pixel number within an échelle order.