Scientific Modes
The observing modes described in this section are those intended for the acquisition of scientific data by the observer. Here we describe all possible scientific observations to be carried out either with one of the MEGARA IFUs or the Fiber MOS.
LCB IFU scientific observation
- Mode:
LCB IFU scientific observation
- Usage:
Online, Offline
- Key:
MegaraLcbImage
- Recipe:
- Recipe input:
LCBImageRecipeInput- Recipe result:
LCBImageRecipeResult
This mode sequence includes the required actions to obtain scientifically-valid data with the LCB IFU instrument mode of MEGARA.
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 LCB IFU, to move the focusing mechanism to the position pre-defined for the specific VPH of choice, and to expose a certain time and to readout the detector in a series of exposures, being this series the LCB IFU image set.
A pre-requisite for this observing mode is to have previously executed a “Fine acquisition with the LCB IFU” auxiliary observing mode (TBC depending on the system absolute positioning precision and the observer requirements).
As part of the MEGARA on-line quick-look software the images to be obtained by this observing mode should be processed and the spectra extracted so to produce a view of the field at a selectable wavelength within the wavelength range covered by the VPH of choice. As a number of Fiber MOS positioners are devoted to the measure of the sky background simultaneously with the LCB IFU observations the on-line quick-look software should be able to subtract the spectrum of the sky from the spectra in each IFU spaxel and from the maps generated above. This software should have information on the specific focal-plane cover configuration being used.
In the case of observing relatively extended targets (comparable in size or larger than the LCB IFU field of view) but a mapping observing mode is not required to be used a blank-sky image set should be obtained using the same instrumental configuration as for the science target.
Products
The observer will obtain LCB IFU image sets as part of the routine scientific operation of the instrument. The observatory staff could also make use of this observing mode to verify the status of the instrument using any source different from a standard star. In the case of observing a standard star the calibration mode standard star with the LCB IFU could be used instead.
Recipe, inputs and results
- class megaradrp.recipes.scientific.lcb.LCBImageRecipe(*args, **kwargs)
Process LCB images.
This recipe processes a set of images obtained in LCB image mode and returns the sky subtracted RSS.
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 the 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_apertures 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 in the field final_rss of the recipe result.
If a master_sensitivity is provided (optional), RSS products will be flux calibrated. If reference_extinction is provided (optional), final_rss and reduced_rss will be extinction corrected. Notice that sky_rss is not corrected from extinction.
- class ImageRecipeInput(*args, **kwds)
ImageRecipeInput documentation.
- Attributes:
- diffuse_light_imageDiffuseLightCorrection, requirement, optional
Diffuse light correction image
- extraction_offsetListOfType, requirement, optional, default=[0.0]
Offset traces for extraction
- ignored_sky_bundlesListOfType, requirement, optional
Ignore these sky bundles
- master_aperturesMultiType, requirement
Apertures information for extraction
- master_biasMasterBias, requirement
Master BIAS image
- master_bpmMasterBPM, requirement, optional
Master Bad Pixel Mask
- master_darkMasterDark, requirement, optional
Master DARK image
- master_fiberflatMasterFiberFlat, requirement
Master fiber flat calibration
- master_sensitivityMasterSensitivity, requirement, optional
Master sensitivity for flux calibration
- master_slitflatMasterSlitFlat, requirement, optional
Master slit flat calibration
- master_twilightMasterTwilightFlat, requirement, optional
Master twlight flat calibration
- master_wlcalibWavelengthCalibration, requirement
Wavelength calibration table
- methodstr, requirement, optional, default=median
Combination method
- method_kwargsdict, requirement, optional
Arguments for combination method
- obresultObservationResultType, requirement
Observation Result
- reference_extinctionReferenceExtinctionTable, requirement, optional
Reference extinction
- relative_thresholdfloat, requirement, optional, default=0.3
Threshold for peak detection
- sky_rssSkyRSS, requirement, optional
Row Stacked Spectra of the sky
- class LCBImageRecipeResult(*args, **kwds)
LCBImageRecipeResult documentation.
- Attributes:
- final_rssProcessedRSS, product
- reduced_imageProcessedFrame, product
- reduced_rssProcessedRSS, product
- sky_rssProcessedRSS, product
- RecipeInput
alias of
ImageRecipeInput
- RecipeResult
alias of
LCBImageRecipeResult
Fiber MOS scientific observation
- Mode:
Fiber MOS scientific observation
- Usage:
Online, Offline
- Key:
MegaraMosImage
- Recipe:
- Recipe input:
MOSImageRecipeInput- Recipe result:
MOSImageRecipeResult
This mode sequence includes the required actions to observe a list of targets with known celestial coordinates with MEGARA using the Fiber MOS instrument mode. The information on the assignment of targets and positioners is included in the form of a set of input catalogues generated off-line by the MEGARA Observing Preparation Software Suite (MOPSS). The reference position for each positioner is the center of the central fiber of the 7-fiber minibundle. This observing mode could be run with one of the sides of the focal-plane cover closed in order to reduce the cross-talk between positioners that would be placed adjacent in the pseudo-slit. Thus, the input catalogues should be specific of the focal-plane cover configuration to be used and both the on-line quick-look software and the off-line pipeline should include that information as a parameter or set of parameters. Note that the Fiber MOS catalogues and configuration files could be designed for their use under any focal-plane cover configuration. Even in that case the data processing software should know under which configuration a given image set was obtained.
Requirements
This observing 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 all robotic positioners with a target associated in the input catalogues to the position of the corresponding target (these include science targets, reference stars for fine acquisition and positioners devoted to blank-sky measurements) and to expose a certain time and to readout the detector in a series of exposures, being this series the Fiber MOS image set.
A pre-requisite for running this observing mode is to have previously executed a “Fine acquisition with the Fiber MOS” auxiliary observing mode on the same field.
As part of the MEGARA on-line quick-look software, the image (or images) obtained should be processed and the spectra extracted. The observer might define a number of positioners to be placed on blank-sky regions of the field in order to improve sky subtraction. Alternatively, the user can also define a blank sky position. This is particularly important when observing individual stars in a nearby (Local Group) galaxy, for example, where the emission from the host galaxy is expected to contaminate even the outermost positioners. Should that be the case, the on-line quick-look software should be able to derive a sky spectrum from the blank-sky observation (if present) or the spectra of these positioners (if defined and no blank-sky observation is available) and subtract it from the spectra of the targets. The processed spectra should then be visualized using the on-line quick-look software. If neither a blank-sky observation nor blank-sky positioners are available no sky subtraction will be performed.
Products
The observer will obtain Fiber MOS image sets as part of the routine scientific operation of the instrument. The observatory staff could also make use of this observing mode to verify the status of the instrument.
Recipe, inputs and results
- class megaradrp.recipes.scientific.mos.MOSImageRecipe(*args, **kwargs)
Process MOS images.
This recipe processes a set of images obtained in MOS image mode and returns the sky subtracted RSS.
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 the 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_apertures 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 in the field final_rss of the recipe result.
If a master_sensitivity is provided (optional), RSS products will be flux calibrated. If reference_extinction is provided (optional), final_rss and reduced_rss will be extinction corrected. Notice that sky_rss is not corrected from extinction.
- class ImageRecipeInput(*args, **kwds)
ImageRecipeInput documentation.
- Attributes:
- diffuse_light_imageDiffuseLightCorrection, requirement, optional
Diffuse light correction image
- extraction_offsetListOfType, requirement, optional, default=[0.0]
Offset traces for extraction
- ignored_sky_bundlesListOfType, requirement, optional
Ignore these sky bundles
- master_aperturesMultiType, requirement
Apertures information for extraction
- master_biasMasterBias, requirement
Master BIAS image
- master_bpmMasterBPM, requirement, optional
Master Bad Pixel Mask
- master_darkMasterDark, requirement, optional
Master DARK image
- master_fiberflatMasterFiberFlat, requirement
Master fiber flat calibration
- master_sensitivityMasterSensitivity, requirement, optional
Master sensitivity for flux calibration
- master_slitflatMasterSlitFlat, requirement, optional
Master slit flat calibration
- master_twilightMasterTwilightFlat, requirement, optional
Master twlight flat calibration
- master_wlcalibWavelengthCalibration, requirement
Wavelength calibration table
- methodstr, requirement, optional, default=median
Combination method
- method_kwargsdict, requirement, optional
Arguments for combination method
- obresultObservationResultType, requirement
Observation Result
- reference_extinctionReferenceExtinctionTable, requirement, optional
Reference extinction
- relative_thresholdfloat, requirement, optional, default=0.3
Threshold for peak detection
- sky_rssSkyRSS, requirement, optional
Row Stacked Spectra of the sky
- class MOSImageRecipeResult(*args, **kwds)
MOSImageRecipeResult documentation.
- Attributes:
- final_rssProcessedRSS, product
- reduced_imageProcessedFrame, product
- reduced_rssProcessedRSS, product
- sky_rssProcessedRSS, product
- RecipeInput
alias of
ImageRecipeInput
- RecipeResult
alias of
MOSImageRecipeResult