Standard star with the Fiber MOS

Mode:Standard star with the FIBER MOS Usage:Offline, Online Key:MEGARA_MOS_STD_STAR Recipe:MOSStandardRecipe Recipe input:MOSStandardRecipeInput Recipe result:MOSStandardRecipeResult

This observing mode includes the required actions to obtain those calibration images needed to correct for the variation in the response of the system along the spectral direction. The difference between this mode and the two precedent observing modes is that in this case the spectrophotometric standard star is observed through one of the robotic positioners of the Fiber-MOS subsystem.

As in Standard star with the IFUs observing modes, the calibration is performed by observing one or several spectrophotometric stars with the same instrument configuration that for the scientific observations. Depending on the number of standard stars observed and the weather conditions two different types of calibration could be achieved, absolute or relative. In the case of the former calibration an aperture correction should be applied to take into account the possible flux losses from the standard stars when observed through one of the ~1.6-arcsec-wide robotic positioners.

Requirements

This mode requires having the focal-plane cover configured, the instrument shutter open, to configure the VPH mechanism to select the grating to be used, to set the instrument mode to Fiber MOS, to move the focusing mechanism to the position pre-defined for the specific VPH of choice, to move one of the robotic positioners to the position of the spectrophotometric standard star (other positioners could be also moved if needed) and to expose a certain time and to readout the detector in a series of exposures, being this series the image set containing the spectral energy distribution of the spectrophotometric standard star.

This observing mode could still be carried out with one of the sides of the focal-plane cover closed. However, as the (commonly rather bright) spectrophotometric standard star is the only object of interest in the field, the other positioners would not be observing scientific targets, so the level of cross-talk between these and the positioner devoted to the standard star should be negligible. Thus, the use of the focal-plane cover, although considered, is not recommended for this specific observing mode.

In order to place the robotic positioner(s) on the corresponding target(s) a set of input catalogues previously generated by the observer using MOPSS (MEGARA Observing Preparation Software Suite) are needed.

Products

Standard star image sets are to be obtained only as part of the routine calibration activities performed by the observer that are needed for processing data for scientific exploitation.

Recipe, inputs and results

class megaradrp.recipes.calibration.mosstdstar.MOSStandardRecipe(*args, **kwds)

Process MOS Standard Star Recipe.

This recipe processes a set of images obtained in MOS Stardard Star image mode and returns the total flux of the star.

See also

megaradrp.recipes.calibration.lcbstdstar.LCBStandardRecipe

Notes

Images provided by obresult are trimmed and corrected from overscan, bad pixel mask (if master_bpm is not None), bias, dark current (if master_dark is not None) and slit-flat (if master_slitflat is not None).

Images thus corrected are then stacked using the median. The result of the combination is saved as an intermediate result, named ‘reduced_image.fits’. This combined image is also returned in the field reduced_image of the recipe result.

The apertures in the 2D image are extracted, using the information in master_traces and resampled according to the wavelength calibration in master_wlcalib. Then is divided by the master_fiberflat. The resulting RSS is saved as an intermediate result named ‘reduced_rss.fits’. This RSS is also returned in the field reduced_rss of the recipe result.

The sky is subtracted by combining the the fibers marked as SKY in the fibers configuration. The RSS with sky subtracted is returned ini the field final_rss of the recipe result.

The flux of the star is computed by adding the 7 fibers corresponding to the bundle containing the star and returned as star_spectrum.

class MOSStandardRecipeInput(*args, **kwds)

MOSStandardRecipeInput documentation.

Attributes

master_bias	(MasterBias, requirement) Master BIAS image
master_bpm	(MasterBPM, requirement, optional) Master Bad Pixel Mask
master_dark	(MasterDark, requirement, optional) Master DARK image
master_fiberflat	(MasterFiberFlat, requirement) Master fiber flat calibration
master_slitflat	(MasterSlitFlat, requirement, optional) Master slit flat calibration
master_traces	(TraceMap, requirement) Trace information of the Apertures
master_twilight	(MasterSlitFlat, requirement) Master slit flat calibration
master_wlcalib	(WavelengthCalibration, requirement) Wavelength calibration table
obresult	(ObservationResultType, requirement) Observation Result
position	(list, requirement) Position of the reference object

class MOSStandardRecipe.MOSStandardRecipeResult(*args, **kwds)

MOSStandardRecipeResult documentation.

Attributes

final_rss	(ProcessedRSS, product)
qc	(QualityControlProduct, product)
reduced_image	(ProcessedFrame, product)
reduced_rss	(ProcessedRSS, product)
sky	(ProcessedRSS, product)
star_spectrum	(ProcessedSpectrum, product)

MOSStandardRecipe.RecipeInput

alias of MOSStandardRecipeInput

MOSStandardRecipe.RecipeResult

alias of MOSStandardRecipeResult