FgcmOutputProductsTask

FgcmOutputProductsTask uses the output from FgcmFitCycleTask to generate a full suite of output products (photometric calibration files, fgcm_photoCalib; atmosphere transmissions, transmission_atmosphere_fgcm; and standard star calibrated reference catalogs ref_cat) for use in downstream processing.

This is the fourth and final task in a typical fgcmcal processing chain. The first is FgcmMakeLutTask, the second is FgcmBuildStarsTableTask or FgcmBuildStarsTask, and the third is FgcmFitCycleTask.

FgcmOutputProductsTask is available as a command-line task, fgcmOutputProducts.py.

Processing summary

FgcmOutputProductsTask reads in outputs from FgcmFitCycleTask, with the cycleNumber specified in the config file, translates these tables to formats used by coaddition and other downstream processing.

fgcmOutputProducts.py command-line interface

Note that no --id arguments are used by fgcmOutputProducts.py.

fgcmOutputProducts.py REPOPATH [@file [@file2 ...]] [--output OUTPUTREPO | --rerun RERUN] [--config cycleNumber=finalCycleNumber] [other options]

Key arguments:

REPOPATH
The input Butler repository’s URI or file path.

Key options:

--config cycleNumber=finalCycleNumer:
The cycleNumber used for the isFinalCycle run of FgcmFitCycleTask

See also

See Command-line task argument reference for details and additional options.

Python API summary

from lsst.fgcmcal.fgcmOutputProducts import FgcmOutputProductsTask
classFgcmOutputProductsTask(butler=None, **kwargs)

Output products from FGCM global calibration...

attributeconfig

Access configuration fields and retargetable subtasks.

methodrun(dataRefDict, filterMap, returnCatalogs=True, butler=None)

Run the output products task...

methodrunDataRef(butler)

Make FGCM output products for use in the stack...

See also

See the FgcmOutputProductsTask API reference for complete details.

Butler datasets

When run as the fgcmOutputProducts.py command-line task, or directly through the runDataRef method, FgcmOutputProductsTask obtains datasets from the input Butler data repository and persists outputs to the output Butler data repository. Note that configurations for FgcmOutputProductsTask, and its subtasks, affect what datasets are persisted and what their content is.

Input datasets

fgcmStandardStars
Catalog of standard stars from fit.
fgcmZeropoints
Catalog of zero-point information.
fgcmAtmosphereParameters
Catalog of atmosphere parameters.
fgcmBuildStars_config or fgcmBuildStarsTable_config
Configuration of task used to build stars for the fgcmcal run. Only one should be available depending on the specific task used.
fgcmFitCycle_config
Configuration of FgcmFitCycleTask used for the final fit cycle.

Output datasets

fgcm_stars
Reference catalog of standard stars.
fgcm_photoCalib
One fgcm_photoCalib photometric calibration file is output for each visit / ccd.
transmission_atmosphere_fgcm
One atmospheric transmission curve is output for each visit.

The reference catalog (fgcm_stars) is an lsst.afw.table.SimpleCatalog that can be used as a reference catalog, including band_flux and band_fluxErr measurements per band (in nJy), as well as additional information including band_nGood (the number of photometric observations per band), band_nTotal (the total number of observations per band), and band_nPsfCandidate (the number of observations per band that were flagged as PSF candidates).

Retargetable subtasks

photoCal

Default
lsst.pipe.tasks.photoCal.PhotoCalTask
Field type
ConfigurableField
task to perform ‘absolute’ calibration

refObjLoader

Default
lsst.meas.algorithms.loadIndexedReferenceObjects.LoadIndexedReferenceObjectsTask
Field type
ConfigurableField
reference object loader for ‘absolute’ photometric calibration

Configuration fields

connections

Data type
lsst.pipe.base.config.Connections
Field type
ConfigField
Configurations describing the connections of the PipelineTask to datatypes

cycleNumber

Default
None
Field type
int Field
Final fit cycle from FGCM fit

datasetConfig

Data type
lsst.meas.algorithms.ingestIndexReferenceTask.DatasetConfig
Field type
ConfigField
Configuration for writing/reading ingested catalog

doApplyMeanChromaticCorrection

Default
True
Field type
bool Field
Apply the mean chromatic correction to the zeropoints?

doAtmosphereOutput

Default
True
Field type
bool Field
Output atmospheres in transmission_atmosphere_fgcm format

doComposeWcsJacobian

Default
True
Field type
bool Field
Compose Jacobian of WCS with fgcm calibration for output photoCalib?

doRefcatOutput

Default
True
Field type
bool Field
Output standard stars in reference catalog format

doReferenceCalibration

Default
False
Field type
bool Field
Transfer ‘absolute’ calibration from reference catalog? This afterburner step is unnecessary if reference stars were used in the full fit in FgcmFitCycleTask.

doZeropointOutput

Default
True
Field type
bool Field
Output zeropoints in fgcm_photoCalib format

referenceMinMatch

Default
50
Field type
int Field
Minimum number of stars matched to reference catalog to be used in statistics

referencePixelizationMinStars

Default
200
Field type
int Field
Minimum number of stars per healpix pixel to select for comparisonto the specified reference catalog

referencePixelizationNPixels

Default
100
Field type
int Field
Number of healpix pixels to sample to do comparison. Doing too many will take a long time and not yield any more precise results because the final number is the median offset (per band) from the set of pixels.

referencePixelizationNside

Default
64
Field type
int Field
Healpix nside to pixelize catalog to compare to reference catalog

saveMetadata

Default
True
Field type
bool Field
Flag to enable/disable metadata saving for a task, enabled by default.

Examples

See the cookbook for worked examples.