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: | MEGARA_LCB_IMAGE |
Recipe: | LCBImageRecipe |
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.
Procedure¶
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, **kwds)¶ Process LCB images.
-
class
ImageRecipeInput
(*args, **kwds)¶ ImageRecipeInput 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_twilight (MasterSlitFlat, requirement) Master slit flat calibration obresult (ObservationResultType, requirement) Observation Result tracemap (TraceMap, requirement) Trace information of the Apertures wlcalib (WavelengthCalibration, requirement) Wavelength calibration table
-
class
LCBImageRecipe.
LCBImageRecipeResult
(*args, **kwds)¶ LCBImageRecipeResult documentation.
Attributes
final (ProcessedRSS, product) qc (QualityControlProduct, product) reduced (ProcessedFrame, product) sky (ProcessedRSS, product) target (ProcessedRSS, product)
-
LCBImageRecipe.
RecipeInput
¶ alias of
ImageRecipeInput
-
LCBImageRecipe.
RecipeResult
¶ alias of
LCBImageRecipeResult
-
class
LCB IFU fast mapping¶
Mode: | LCB IFU fast mapping |
---|---|
Usage: | Online, Offline |
Key: | MEGARA_LCB_FAST_MAPPING |
Recipe: | LCBFastMappingRecipe |
Recipe input: | LCBFastMappingRecipeInput |
Recipe result: | LCBFastMappingRecipeResult |
This mode sequence includes the required actions to obtain scientifically valid data with the LCB IFU instrument mode of MEGARA covering a relatively large area of the sky (of an extension equivalent to several LCB FOV). As this mode is intended for the observation of large areas of the sky the exposure times of individual exposures are expected to be short. That implies that the use of the A&G system is not mandatory. By skipping the use of the A&G system throughout the mapping process the observing efficiency dramatically increases. A (slow) mapping observation, where each position in the grid should make use of the A&G system, would have to be defined by the means of individual LCB IFU scientific observing modes. The current observing mode only contemplates the possibility of using the A&G system for the starting position of the mapping grid.
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, to expose a certain time and to readout the detector in a series of exposures, and to repeat the data acquisition in a regular grid of positions on the sky, being this series the LCB IFU fast-mapping image set.
The execution of a “Fine acquisition with the LCB IFU” auxiliary observing mode is optional in this case and it would be only possible for the starting position in the grid.
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 entire mapped field at a selectable wavelength within the wavelength range covered by the VPH of choice. The user can provide a blank-sky position away from the mapping area. As a number of Fiber MOS positioners are devoted to the measure of the sky background simultaneously with the LCB IFU observations, alternatively, the on-line quick-look software could also subtract the spectrum of the sky from the spectra in each IFU spaxel and from the maps generated above. In the latter case (i.e. when no blank-sky position is defined) showing sky-subtracted maps is optional as the sky positioners could be strongly contaminated by emission from the extended target. Note that, in any case, the on-line quick-look software should have information on the configuration of the focal-plane cover as well.
Procedure¶
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.
Recipe, inputs and results¶
-
class
megaradrp.recipes.scientific.lcbfastmapping.
LCBFastMappingRecipe
(*args, **kwds)¶ Process LCB Fast Mapping Recipe.
-
class
LCBFastMappingRecipeResult
(*args, **kwds)¶ LCBFastMappingRecipeResult documentation.
Attributes
final (ProcessedMultiRSS, product) qc (QualityControlProduct, product)
-
class
LCBFastMappingRecipe.
MegaraBaseRecipeInput
(*args, **kwds)¶ MegaraBaseRecipeInput documentation.
Attributes
obresult (ObservationResultType, requirement) Observation Result
-
LCBFastMappingRecipe.
RecipeInput
¶ alias of
MegaraBaseRecipeInput
-
LCBFastMappingRecipe.
RecipeResult
¶ alias of
LCBFastMappingRecipeResult
-
class
Fiber MOS scientific observation¶
Mode: | Fiber MOS scientific observation |
---|---|
Usage: | Online, Offline |
Key: | MEGARA_MOS_IMAGE |
Recipe: | MOSImageRecipe |
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.
Procedure¶
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, **kwds)¶ Process MOS images.
-
class
ImageRecipeInput
(*args, **kwds)¶ ImageRecipeInput 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_twilight (MasterSlitFlat, requirement) Master slit flat calibration obresult (ObservationResultType, requirement) Observation Result tracemap (TraceMap, requirement) Trace information of the Apertures wlcalib (WavelengthCalibration, requirement) Wavelength calibration table
-
class
MOSImageRecipe.
MOSImageRecipeResult
(*args, **kwds)¶ MOSImageRecipeResult documentation.
Attributes
final (ProcessedRSS, product) qc (QualityControlProduct, product) reduced (ProcessedFrame, product) sky (ProcessedRSS, product) target (ProcessedRSS, product)
-
MOSImageRecipe.
RecipeInput
¶ alias of
ImageRecipeInput
-
MOSImageRecipe.
RecipeResult
¶ alias of
MOSImageRecipeResult
-
class
Standard star with the LCB IFU¶
Mode: | Standard start with the LCB IFU |
---|---|
Usage: | Offline |
Key: | MEGARA_LCB_STD_STAR |
Recipe: | LCBStandardRecipe |
Recipe input: | LCBStandardRecipeInput |
Recipe result: | LCBStandardRecipeResult |
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. This signature is manifested by a change in the conversion factor between the energy surface density hitting the telescope primary mirror and the DUs per CCD pixel with wavelength. Its effect is already present in the original data but it could get modified during the reduction process, e.g. after the fiber-flat correction is applied.
The flux 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 on the weather conditions (mainly transparency) two different types of calibration could be achieved:
- Absolute-flux calibration: The weather conditions during the night should be photometric and a number of spectrophotometric standard stars at different airmasses should be observed. This allows to fully correct from DUs per CCD pixel to energy surface density (typically in erg s-1 cm-2 Å-1) incident at the top of the atmosphere. If only one single standard star is observed (at the airmass of the science object) this correction allows deriving the energy surface density hitting the telescope primary mirror exclusively, unless an atmospheric extinction curve for the observatory and that particular night is assumed. In order to properly flux-calibrate scientific observations at all airmasses several stars should be observed during the night.
- Relative-flux calibration: If the weather conditions are not photometric this correction only allows normalizing the DUs per CCD pixel along the spectral direction so the conversion to incident energy at the top of the atmosphere is the same at all wavelengths. In order for this calibration to be valid the assumption that the effect of the atmosphere (including atmospheric cirrus and possibly thick clouds) on the wavelength dependence of this correction is that given by the atmospheric extinction curve adopted.
Since the observing sequence needed for both types of flux calibration is identical only one observing mode (standard star) needs to be defined.
We will use this same observing mode also for the observation of either telluric standards or radial-velocity standards. The former are needed to correct for the presence of telluric absorptions mainly in the red part of the spectrum and are achieved by means of observing A-type stars at the same airmass and very close in time to the corresponding scientific observation. The latter can used to determine a precise zero point velocity for the instrument at a specific night and to verify its stability from night to night and season to season.
Requirements¶
This mode requires the entire flux of the spectrophotometric standard star to be recovered (even if the star is a telluric or radial-velocity standard), especially when an absolute-flux calibration is needed, so the LCB IFU bundle must be used. The FOV of the LCB IFU is large enough for these observations to be carried out with one of the sides of the focal-plane cover closed. When this calibration is aimed for a set of Fiber-MOS scientific observations, complementary observations of standard stars through the Fiber-MOS minibundles might be also required. This allows verifying the quality and stability of the calibration when two different pseudo-slits are used. Such observing mode is described later.
This mode requires having the focal-plane cover configured (at least one of the sides should be open), 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 image set containing the spectral energy distribution of the spectrophotometric standard star.
In order to distribute the flux from the star across multiple spaxels in the LCB IFU bundle (particularly important in the case of very bright spectrophotometric standard stars) we might also need to apply a small drift motion (typically of a few arcsec per second) to one of the telescope axes at the start of the observation or, more likely, slightly defocus the telescope.
Procedure¶
Products¶
Standard star image sets are to be obtained only as part of the routine calibration activities performed by the observer and that are needed for processing data for scientific exploitation.
Recipe, inputs and results¶
-
class
megaradrp.recipes.scientific.lcbstdstar.
LCBStandardRecipe
¶ Process LCB Standard Recipe.
-
class
ImageRecipeInput
(*args, **kwds)¶ ImageRecipeInput 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_twilight (MasterSlitFlat, requirement) Master slit flat calibration obresult (ObservationResultType, requirement) Observation Result tracemap (TraceMap, requirement) Trace information of the Apertures wlcalib (WavelengthCalibration, requirement) Wavelength calibration table
-
class
LCBStandardRecipe.
MegaraBaseRecipeResult
(*args, **kwds)¶ MegaraBaseRecipeResult documentation.
Attributes
qc (QualityControlProduct, product)
-
LCBStandardRecipe.
RecipeInput
¶ alias of
ImageRecipeInput
-
LCBStandardRecipe.
RecipeResult
¶ alias of
MegaraBaseRecipeResult
-
class
Standard star with the Fiber MOS¶
Mode: | Standard start with the FIBER MOS |
---|---|
Usage: | Offline |
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.
Procedure¶
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.scientific.mosstdstar.
MOSStandardRecipe
(*args, **kwds)¶ Process MOS Standard Recipe.
-
class
ImageRecipeInput
(*args, **kwds)¶ ImageRecipeInput 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_twilight (MasterSlitFlat, requirement) Master slit flat calibration obresult (ObservationResultType, requirement) Observation Result tracemap (TraceMap, requirement) Trace information of the Apertures wlcalib (WavelengthCalibration, requirement) Wavelength calibration table
-
class
MOSStandardRecipe.
MegaraBaseRecipeResult
(*args, **kwds)¶ MegaraBaseRecipeResult documentation.
Attributes
qc (QualityControlProduct, product)
-
MOSStandardRecipe.
RecipeInput
¶ alias of
ImageRecipeInput
-
MOSStandardRecipe.
RecipeResult
¶ alias of
MegaraBaseRecipeResult
-
class
MEGARA_FLUX_CALIBRATION¶
Mode: | |
---|---|
Usage: | Offline |
Key: | MEGARA_FLUX_CALIBRATION |
Recipe: | PseudoFluxCalibrationRecipe |
Recipe input: | PseudoFluxCalibrationRecipeInput |
Recipe result: | PseudoFluxCalibrationRecipeResult |
Recipe, inputs and results¶
-
class
megaradrp.recipes.calibration.fluxcal.
PseudoFluxCalibrationRecipe
(*args, **kwds)¶ -
class
PseudoFluxCalibrationRecipeInput
(*args, **kwds)¶ PseudoFluxCalibrationRecipeInput documentation.
Attributes
master_bias (MasterBias, requirement) Master BIAS image master_fiberflat (MasterFiberFlat, requirement) Master fiber flat calibration obresult (ObservationResultType, requirement) Observation Result reference_spectrum (MasterFiberFlat, requirement) Reference spectrum traces (TraceMap, requirement) Trace information of the Apertures
-
class
PseudoFluxCalibrationRecipe.
PseudoFluxCalibrationRecipeResult
(*args, **kwds)¶ PseudoFluxCalibrationRecipeResult documentation.
Attributes
calibration (ProcessedFrame, product) calibration_rss (ProcessedRSS, product) qc (QualityControlProduct, product)
-
PseudoFluxCalibrationRecipe.
RecipeInput
¶ alias of
PseudoFluxCalibrationRecipeInput
-
PseudoFluxCalibrationRecipe.
RecipeResult
¶ alias of
PseudoFluxCalibrationRecipeResult
-
class
MEGARA_EXTINCTION_STAR¶
Mode: | |
---|---|
Usage: | Offline |
Key: | MEGARA_MOS_STD_STAR |
Recipe: | ExtinctionStarRecipe |
Recipe input: | ExtinctionStarRecipeInput |
Recipe result: | ExtinctionStarRecipeResult |
Recipe, inputs and results¶
-
class
megaradrp.recipes.scientific.extinctionstar.
ExtinctionStarRecipe
(*args, **kwds)¶ Process Extinction Star Recipe.
-
class
ImageRecipeInput
(*args, **kwds)¶ ImageRecipeInput 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_twilight (MasterSlitFlat, requirement) Master slit flat calibration obresult (ObservationResultType, requirement) Observation Result tracemap (TraceMap, requirement) Trace information of the Apertures wlcalib (WavelengthCalibration, requirement) Wavelength calibration table
-
class
ExtinctionStarRecipe.
MegaraBaseRecipeResult
(*args, **kwds)¶ MegaraBaseRecipeResult documentation.
Attributes
qc (QualityControlProduct, product)
-
ExtinctionStarRecipe.
RecipeInput
¶ alias of
ImageRecipeInput
-
ExtinctionStarRecipe.
RecipeResult
¶ alias of
MegaraBaseRecipeResult
-
class
MEGARA_SENSITIVITY_STAR¶
Mode: | |
---|---|
Usage: | Offline |
Key: | MEGARA_FLUX_CALIBRATION |
Recipe: | SensivityStarRecipe |
Recipe input: | SensivityStarRecipeInput |
Recipe result: | SensivityStarRecipeResult |
Recipe, inputs and results¶
-
class
megaradrp.recipes.scientific.sensivitystar.
SensivityStarRecipe
¶ Process Sensivity Star Recipe.
-
class
ImageRecipeInput
(*args, **kwds)¶ ImageRecipeInput 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_twilight (MasterSlitFlat, requirement) Master slit flat calibration obresult (ObservationResultType, requirement) Observation Result tracemap (TraceMap, requirement) Trace information of the Apertures wlcalib (WavelengthCalibration, requirement) Wavelength calibration table
-
class
SensivityStarRecipe.
MegaraBaseRecipeResult
(*args, **kwds)¶ MegaraBaseRecipeResult documentation.
Attributes
qc (QualityControlProduct, product)
-
SensivityStarRecipe.
RecipeInput
¶ alias of
ImageRecipeInput
-
SensivityStarRecipe.
RecipeResult
¶ alias of
MegaraBaseRecipeResult
-
class