Produce a coadded, sky-subtracted, wavelength-calibrated, flux-calibrated datacube from a group of SKY-OBJECT pairs of IFU frames.
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The
spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a
way that there are no longer spaces between the spectra, the spectra are arranged in the
order in which they appear in the field of view and they are approximately aligned in the
dispersion direction. The spectrum is flat-fielded and sky-object pairs are now subtracted. The
wavelength calibration previously measured from the arc spectrum is used to apply a
common, linear wavelength scale to each row of the the sky-subtracted 2-d spectrum. The
resulting frame is coadded to the group, which is then rearranged to form a data-cube. The
spectral dimension of the data-cube is divided by the standard-star spectrum and flux
calibrated. Images can be extracted over a range of wavelengths specified in a file called
extract.images placed in the $ORAC_DATA_OUT directory, and can be displayed by editing the disp.dat
file.
A suitable flat-field spectrum, arc spectrum and standard-star spectrum should previously have been reduced and filed with the calibration system.
Sky-object pairs may be observed in any sequence (for example sky-object-object-sky or object-sky-object-sky). Any observations with telescope offsets greater than 30 arcsec will be assumed to be a sky position. It is recommended that the observation types are set to OBJECT and SKY as appropriate (this is essential if your offsets to sky are smaller than 30 arcsec).
Variances are propagated if Kappa 1.0 or later is available. A warning is displayed if variances are lost.
A variant of this recipe, EXTENDED_SOURCE_NOSTD, is available which does not divide the spectrum by a standard-star or flux calibrate the spectrum. It may be useful to specify this recipe on the command line when running Orac-dr if you choose to defer observation of your standard until after you have observed your object.
The individual frames with slices extracted and approximately aligned have the suffix _ext. The
flat-fielded, scrunched, sky-subtracted pairs have the suffix _scr.
Several group files are created (with names starting gu). The coadded scrunched 2-d spectrum has the
suffix _scr. This is formed into a datacube with the suffix _cub. A cube which has been divided by the
standard-star spectrum is formmed with the suffix _dbsc and a flux calibrated datacube
with the suffix _fc. A white-light image is extracted from this datacube with the suffix
_im.
Produce a coadded, sky-subtracted, wavelength-calibrated, datacube from a group of SKY-OBJECT pairs of IFU frames.
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The
spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a
way that there are no longer spaces between the spectra, the spectra are arranged in the
order in which they appear in the field of view and they are approximately aligned in the
dispersion direction. The spectrum is flat-fielded and sky-object pairs are now subtracted. The
wavelength calibration previously measured from the arc spectrum is used to apply a
common, linear wavelength scale to each row of the the sky-subtracted 2-d spectrum. The
resulting frame is coadded to the group, which is then rearranged to form a data-cube. The
spectral dimension of the data-cube is divided by the standard-star spectrum and flux
calibrated. Images can be extracted over a range of wavelengths specified in a file called
extract.images placed in the $ORAC_DATA_OUT directory, and can be displayed by editing the disp.dat
file.
A suitable flat-field spectrum and arc spectrum should previously have been reduced and filed with the calibration system.
Sky-object pairs may be observed in any sequence (for example sky-object-object-sky or object-sky-object-sky). Any observations with telescope offsets greater than 30 arcsec will be assumed to be a sky position. It is recommended that the observation types are set to OBJECT and SKY as appropriate (this is essential if your offsets to sky are smaller than 30 arcsec).
Variances are propagated if Kappa 1.0 or later is available. A warning is displayed if variances are lost.
This is a variant of EXTENDED_SOURCE which does not divide the spectrum by a standard-star or flux calibrate the spectrum. This recipe should be specified on the command line when running Orac-dr if you choose to defer observation of your standard until after you have observed your object.
The individual frames with slices extracted and approximately aligned have the suffix _ext. The
flat-fielded, scrunched, sky-subtracted pairs have the suffix _scr. No datacube is formed from
individual frames or pairs.
Several group files are created (with names starting gu). The coadded scrunched 2-d spectrum has the
suffix _scr. This is formed into a datacube with the suffix _cub. A white-light image is extracted from
this datacube with the suffix _im.
Reduces an IFU arc frame to the stage that it can be used to generate an arc-lines list.
This recipe reduces a single IFU arc frame to a form that can be used to generate an arc lines list file.
These are static calibration files stored in $ORAC_DATA_CAL/grisms/, which should rarely need to be
re-generated.
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a way that there are no longer spaces between the spectra, the spectra are arranged in the order in which they appear in the field of view and they are approximately aligned in the dispersion direction. The spectrum is flat-fielded.
A suitable flat-field spectrum should previously have been reduced and filed with the calibration system.
Variances are propagated.
Observers should not need this recipe.
Reduce a group of sky-object pairs of IFU frames, mosaicking datacubes using telescope offsets.
This recipe produces a coadded, sky-subtracted, wavelength-calibrated, flux-calibrated datacube from a group of sky-object pairs of IFU frames. The telescope offsets are used to mosaic datacubes together, allowing a region larger than the field of view of the IFU to be mapped.
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a way that there are no longer spaces between the spectra, the spectra are arranged in the order in which they appear in the field of view and they are approximately aligned in the dispersion direction. The spectrum is flat-fielded and the wavelength calibration measured from the arc spectrum is used to apply a common, linear wavelength scale to each row of the 2-d spectrum.
Sky-object pairs are now subtracted, and the resulting frame is rearranged to form a data-cube, which is divided by the standard-star spectrum, flux calibrated and mosaicked into the group.
A suitable flat-field spectrum, arc spectrum and standard-star spectrum should previously have been reduced and filed with the calibration system.
It is recommended that the observation types of the observations are set to OBJECT and SKY as appropriate. This is inconvenient if you wish to set up a sequence using an offset iterator in orac-ot, so any frames with a telescope offset greater than 30 arcsec will be assumed to be a sky position.
Variances are propagated if Kappa 1.0 or later is available. A warning is displayed if variances are lost.
Any number of sky-object pairs in any jitter pattern may be used.
MAP_EXTENDED_SOURCE_NOSTD, is available which does not divide
the spectrum by a standard-star or flux calibrate the spectrum. It may be useful to
specify this recipe on the command line when running Orac-dr if you choose to defer
observation of your standard until after you have observed your object.
The individual frames with slices extracted and approximately aligned have the suffix _ext. The
flat-fielded, scrunched, sky-subtracted pairs have the suffix _scr. A datacube is formed from each pair
with the suffix _cub.
The datacubes are mosiaced into a file with the suffix _mos. A white-light image is extracted from this
datacube with the suffix _im.
Reduce a group of sky-object pairs of IFU frames, mosaicking datacubes using telescope offsets.
This recipe produces a coadded, sky-subtracted, wavelength-calibrated, datacube from a group of sky-object pairs of IFU frames. The telescope offsets are used to mosaic datacubes together, allowing a region larger than the field of view of the IFU to be mapped.
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a way that there are no longer spaces between the spectra, the spectra are arranged in the order in which they appear in the field of view and they are approximately aligned in the dispersion direction. The spectrum is flat-fielded and the wavelength calibration measured from the arc spectrum is used to apply a common, linear wavelength scale to each row of the 2-d spectrum.
Sky-object pairs are now subtracted, and the resulting frame is rearranged to form a data-cube, which is mosaicked into the group.
A suitable flat-field spectrum and arc spectrum should previously have been reduced and filed with the calibration system.
It is recommended that the observation types of the observations are set to OBJECT and SKY as appropriate. This is inconvenient if you wish to set up a sequence using an offset iterator in orac-ot, so any frames with a telescope offset greater than 30 arcsec will be assumed to be a sky position.
Variances are propagated if Kappa 1.0 or later is available. A warning is displayed if variances are lost.
Any number of sky-object pairs in any jitter pattern may be used.
The individual frames with slices extracted and approximately aligned have the suffix _ext. The
flat-fielded, scrunched, sky-subtracted pairs have the suffix _scr. A datacube is formed from each pair
with the suffix _cub.
The datacubes are mosiacked into a file with the suffix _mos. A white-light image is extracted from this
datacube with the suffix _im.
Creates a text log summarising file headers
This recipe is used to create a text log summarising the file headers of a group of observations. It is often used to create a log file describing a whole night’s worth of observations.
For full details, see the documentation for the spectroscopy _NIGHT_LOG_ primitive.
This recipe calls the primitive in such a way that the log file appears in $ORAC_DATA_IN.
An ‘on-the-fly’ night log is created in $ORAC_DATA_OUT as spectroscopy data is reduced by the pipeline.
This is done by a call to _NIGHT_LOG_ from _SPECTROSCOPY_HELLO_.
The spectroscopy recipe: NIGHT_LOG
The ifu recipe: NIGHT_LOG_LONG
The ifu primitive: _NIGHT_LOG_
Creates a text log detailing file headers
This recipe does the same as the NIGHT_LOG recipe, except that it produces a more detailed log.
The spectroscopy recipe: NIGHT_LOG_LONG
The ifu recipe: NIGHT_LOG
The ifu primitive: _NIGHT_LOG_
This recipe is used to reduce an IFU arc spectrum. A wavelength calibration is obtained for each row of the spectrum. The file containing these calibrations is filed with the calibration system and used to apply a common, linear wavelength calibration to all rows of subsequent observations.
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a way that there are no longer spaces between the spectra. The spectra are now arranged in the order in which they appear in the field of view and approximately aligned in the dispersion direction. The spectrum is divided by the flat-field.
The Figaro Iarc task is then used to obtain a wavelength calibration for each row, using a pre-calibrated arc file to provide the initial fit. Finally all the rows are scrunched to a common, linear wavelength scale to allow the observer to check that the wavelength calibration was correct (i.e. that the spectra are now straight).
A flat-field spectrum must have been reduced and filed as a calibration. This is essential for locating the positions of the spectra.
The spectrum from each slice is smoothed with a -pixel box filter before wavelength calibration, primarily to cover bad pixels.
Variances are propagated, but are not used by Iarc when wavelength calibrating.
The arc is wavelength calibrated using a list of arc lines from a pre-calibrated arc
spectrum to provide an initial fit. These are expected to be constant and are stored in
the $ORAC_DATA_CAL/grisms/ directory. The appropriate file (same grism and arc lamp) is
provided by the calibration system.
The recipe checks the r.m.s. value of the wavelength fit returned by Iarc, and will warn the user if this value seems too high. The observer is recommended to always look at the scrunched arc frame. If the wavelength calibration has worked successfully then all the arc lines should be straight, and the frame should be virtually indistinguishable from a long-slit spectrum.
A file giving the wavelength calibration to be applied to each row is generated with a filename
extension of .iar.
A file containing the arc frame with all rows scrunched to a common wavelength scale is produced
with a suffix of _scr.
This recipe is used to reduce an IFU flat-field spectrum. The normalised flat is filed with the calibration system.
The relative positions of the slice spectra on the array are contained in a static look-up table. The flat field frame is used to measure the offset of these positions (they are shifted vertically by different amounts for different grisms). This value is filed with the calibration system for use when reducing subsequent frames.
The separate slice spectra are extracted from the frame and rearranged in a new 2-d frame in the correct order (the order in which they cover the 2-d field of view) and approximately aligned in the spectral axis. This produces a frame that looks more like a long-slit spectrum.
The frame is now treated as a standard long-slit spectrum. The image is collapsed in the -direction, a black-body spectrum is fitted to this and all rows of the flat field are divided by this spectrum to remove the characteristics of the lamp from the flat-field (this does not have to be done precisely because the same flat-field is used for object frames and flux calibrators, so it cancels out anyway). The image is normalised to have a mean value of 1. The flat field is filed with the calibration system.
Variances are propagated.
The flat-field accounts for the difference in transmission from one slice to another as well as pixel to pixel variation.
The flat field is used to find the offset between the -positions
of the spectra from each slice and the positions given in $ORAC_DATA_CAL/ifu_profile.dat.
The offset measured is stored in index.offset.
The normalised flat is stored in flat_<n>, where <n> is the observation number.
Reduces a single IFU frame, producing a wavelength calibrated datacube
This recipe reduces a single IFU frame (i.e. no sky subtraction or coadding is carried out).
Read-noise and Poisson variances are added to the frame and a bad pixel mask is applied. The spectrum from each slice of the IFU is cut out of the frame and pasted in a new frame in such a way that there are no longer spaces between the spectra, the spectra are arranged in the order in which they appear in the field of view and they are approximately aligned in the dispersion direction. The spectrum is flat-fielded and the wavelength calibration measured from the arc spectrum is used to apply a common, linear wavelength scale to each row of the the 2-d spectrum.
Once all the rows of the image are scrunched to a common linear wavelength scale the 2-d spectrum from each slice is cut out and used to form a single (, ) plane of the (, , ) datacube.
A suitable flat-field spectrum and arc spectrum should previously have been reduced and filed with the calibration system.
Variances are propagated if Kappa 1.0 or later is available. A warning is displayed if variances are lost.
Reduce IFU standard-star observations with a separate sky position
Take a series of standard-star observations and extract and file a standard-star spectrum. This recipe is designed for use when an offset sky position has been used. The frames are subtracted in pairs, giving a sky-subtracted spectrum, which is extracted using optimal extraction. The spectral type and magnitude of the star is obtained from the Simbad database. The resulting spectrum is divided by a black-body spectrum of the appropriate temperature and filed as a calibration frame.
A suitable flat-field spectrum and arc spectrum should previously have been reduced and filed with the calibration system.
Sky-object pairs may be observed in any sequence (for example sky-object-object-sky or object-sky-object-sky). Any observations with telescope offsets greater than 30 arcsec will be assumed to be a sky position. It is recommended that the observation types are set to OBJECT and SKY as appropriate (this is essential if your offsets to sky are smaller than 30 arcsec).
Variances are propagated.
Based on the spectroscopy recipe of the same name, and uses spectroscopy primitives.
A datacube is formed of each subtracted pair and an image is extracted to allow you to confirm that your target is suitably located on the field, but no coadded datacube is formed.
The standard-star spectrum divided by a black-body spectrum will be
written to a file with the name std_<n>_sp. A datacube in which every
position contains this spectrum is created with the name std_<n>_cube.
Reduce IFU standard-star observations when the star has been offset within the field of the IFU.
Take a series of standard-star observations and extract and file a standard-star spectrum. This recipe is designed for use when the star has been offset within the field of the IFU (similar to offsetting along the slit in conventional spectroscopy). The frames are subtracted in pairs, giving a positive and negative spectrum. The two spectra are extracted using optimal extraction and averaged. The resulting spectrum is divided by a black-body spectrum of the appropriate temperature and filed as a calibration frame.
A suitable flat-field spectrum and arc spectrum should previously have been reduced and filed with the calibration system.
Variances are propagated.
A datacube is formed of each subtracted pair and an image is extracted to allow you to confirm that your target is suitably located on the field, but no coadded datacube is formed.
The standard-star spectrum divided by a black-body spectrum will be
written to a file with the name std_<n>_sp. A datacube in which every
position contains this spectrum is created with the name std_<n>_cube.