Data products

These data products are saved to disk as FITS files. MEGARA DRP makes use of the FITS headers to record information about the data processing. This information may be recorded using other methods as well, such as the GTC Database.

The following headers are included in all image data products and record information about the version of Numina and the name and version of the recipe used.

NUMXVER = '0.13.0   '           / Numina package version
NUMRNAM = 'BiasRecipe'          / Numina recipe name
NUMRVER = '0.1.0   '            / Numina recipe version
NUMTYP  = 'TARGET  '            / Data product type

HISTORY keywords may be used also, but the information in these keyword may not be easily indexed.

Generic types

Processed Frame

Processed Frame is the type of any image produced by the pipeline that represents a view of the detector. Its size may be 4096x4112 for trimmed images or 4196x4212 for unprocessed, raw images.

Processed Frame is represented by ProcessedFrame.

Processed RSS

Processed Row Stacked Spectra is the type of any image produced by the pipeline that represents a view of the focal plane, using extracted fibers. It will have 623 rows in LCB mode and 644 rows in MOS mode, each row representing the extracted spectrum of one fiber. The number of columns will be 4112 or larger, depending on the stage of the reduction.

Procesed RSS images will tipically have a FIBERS extension.

Processed RSS is represented by ProcessedRSS.

Processed Spectrum

Processed spectrum is the type of any image produced by the pipeline that represents the spectrum of one object. Its data content will be a 1D array.

Processed Spectrum is represented by ProcessedSpectrum.

Calibrations

Master Bias frames

Bias frames are produced by the recipe BiasRecipe. Each bias frame is a multiextension FITS file with the following extensions.

Extension name Type Version Contents
PRIMARY Primary   The bias level
VARIANCE Image   Variance of the bias level
MAP Image   Number of pixels used to compute the bias level

Master bias frames are represented by MasterBias.

Master Dark frames

Master dark frames are produced by the recipe DarkRecipe. Each dark frame is a multiextension FITS file with the following extensions.

Extension name Type Version Contents
PRIMARY Primary   The dark level
VARIANCE Image   Variance of the dark level
MAP Image   Number of pixels used to compute the dark level

Master dark frames are represented by MasterDark.

Master Bad Pixel Mask

Master Bad Pixel Mask is produced by the recipe BadPixelsMaskRecipe. Each bad pixel mask frame is a multiextension FITS file with the following extensions.

Extension name Type Version Contents
PRIMARY Primary   The Bad Pixel Mask level

Master bad pixel mask frames are represented by MasterBPM.

Master Slit Flat

Master Slit Flat is produced by the recipe SlitFlatRecipe. Each slit flat frame is a multiextension FITS file with the following extensions.

Extension name Type Contents
PRIMARY Primary The Slit Flat level

Masterslit flat frames are represented by MasterSlitFlat.

Master Traces

Master Fiber Flat is produced by the recipe TraceMapRecipe. The result is a JSON file where each one of the records belongs to a given fiber in the RSS file. Moreover, each one of the records has the next information:

Field Type Contents
boxid Integer Number of the box
fibid Integer Number of the fiber
fitparms Primary Polyfit algorithm result
start Integer X-Coordenate in the Flat image
stop Integer X-Coordenate in the Flat image

In the following, a real example of the fourth fiber which is in the first box can be seen in the yaml format:

- boxid: 1
  fibid: 4
  fitparms: [2.6909627476636523e-18, -3.0949058966515047e-14, 1.872326137294402e-10,1.1602592442769502e-06, -0.0009443161994027746, 262.01840282676613]
  start: 4
  stop: 3594

Master Tracemap files are represented by TraceMap.

Master Wavelength Calibration

Master wavelength calibration is produced by the recipe ArcCalibrationRecipe. The result is a JSON file where each one of the records belongs to a given fiber in the RSS file. Moreover, each one of the records or apertures has the next fields:

Field Type Contents
features List List with the arc’s information
function Dictionary Number of pixels used to compute the dark level
id Integer Number the corresponding fiber

Additionally, each one of the elements that belongs to the features corresponds to each one of the arc lines that has been found in the RSS image. The dictionary that each element has, contains the next information:

Field Type Contents
category String Type of the arc
flux Float Flux of the arc
fwhm Float Full Width at Half Maximum of the arc
reference Float Line in the Catalog lines
wavelength Float Predicted line
xpos Float X-coordenate of the arc in the RSS image
ypos Float Y-coordenate of the arc in the RSS image

Finally, the function dictionary has three elements: coefficients, method and order fields. Coefficients has the result of executing the polynomial.polyfit numpy method. Method field has the name of the algorithm used. Order field has the polynomial degree.

In the following, an example of the first fiber of a real JSON file with only two arc lines can be seen:

{
  "aperture": {
    "features": [
      {
        "category": "E",
        "flux": 50212.563405324945,
        "fwhm": 3.438967092459162,
        "reference": 6013.2816999999995,
        "wavelength": 6013.2847301957181,
        "xpos": 33.267395825699928,
        "ypos": 251.10097403866305
      },
    ],
    "function": {
      "coefficients": [6001.573165443434,0.35298729563735487,-2.898410563853586e-05,1.858317850662985e-08,-8.411429549924489e-12,1.4341696725726076e-15],
      "method": "least squares",
      "order": 5
    },
    "id": 2
  }

Master Wavelength calibration file is represented by WavelengthCalibration.

Master Fiber Flat

Master Fiber Flat is produced by the recipe FiberFlatRecipe. Each master fiber flat frame is a multiextension FITS file with the following extensions.

Extension name Type Version Contents
PRIMARY Primary   The Fiber Flat level
FIBERS Image   Description of the focal plane

Master fiber flats frames are represented by MasterFiberFlat.

Master Twilight Flat

Master Twilight Flat is produced by the recipe TwilightFiberFlatRecipe. Each twilight flat frame is a multiextension FITS file with the following extensions.

Extension name Type Version Contents
PRIMARY Primary   The Twilight Flat level
FIBERS Image   Description of the focal plane

Master twilight flat frames are represented by MasterTwilightFlat.

Master Sensitivity

Master sensitivity star image is produced by the recipe Recipe.

Extension name Type Version Contents
PRIMARY Primary   The Sensitivity Star Image level

Master sensitivity star image is represented by MasterSensitivity.

Master Extinction

Master extinction star image is produced by the recipe Recipe.

Extension name Type Version Contents
PRIMARY Primary   The Extinction Star Image level

Master extinction star image is represented by Extinction.

Reference calibrations

The following types represent types used for calibration, but that are not the result of any recipe. Examples of this type are the spectra of flux standars or the tables of spectral lines of calibration lamps.

Reference Spectrum

A tabular representation of the spectral energy distribution of a standard star. The first column contains wavelength (in Angstroms) and the second column the flux in erg/s/cm^2/Angstrom

Reference spectrum is represented by ReferenceSpectrum.