BrightStarStamps¶
- class lsst.meas.algorithms.BrightStarStamps(starStamps, innerRadius=None, outerRadius=None, nb90Rots=None, metadata=None, use_mask=True, use_variance=False, use_archive=False)¶
Bases:
Stamps
Collection of bright star stamps and associated metadata.
- Parameters:
- starStamps
collections.abc.Sequence
[BrightStarStamp
] Sequence of star stamps. Cannot contain both normalized and unnormalized stamps.
- innerRadius
int
, optional Inner radius value, in pixels. This and
outerRadius
define the annulus used to compute the"annularFlux"
values within eachstarStamp
. Must be provided ifnormalize
is True.- outerRadius
int
, optional Outer radius value, in pixels. This and
innerRadius
define the annulus used to compute the"annularFlux"
values within eachstarStamp
. Must be provided ifnormalize
is True.- nb90Rots
int
, optional Number of 90 degree rotations required to compensate for detector orientation.
- metadata
PropertyList
, optional Metadata associated with the bright stars.
- use_mask
bool
- use_variance
bool
If
True
read and write variance data. DefaultFalse
.- use_archive
bool
If
True
read and write an Archive that contains a Persistable associated with each stamp. In the case of bright stars, this is usually aTransformPoint2ToPoint2
, used to warp each stamp to the same pixel grid before stacking.
- starStamps
- Raises:
- ValueError
Raised if one of the star stamps provided does not contain the required keys.
- AttributeError
Raised if there is a mix-and-match of normalized and unnormalized stamps, stamps normalized with different annulus definitions, or if stamps are to be normalized but annular radii were not provided.
Notes
A butler can be used to read only a part of the stamps, specified by a bbox:
>>> starSubregions = butler.get( "brightStarStamps", dataId, parameters={"bbox": bbox} )
Attributes Summary
Methods Summary
append
(item[, innerRadius, outerRadius])Add an additional bright star stamp.
count
(value)extend
(bss)Extend BrightStarStamps instance by appending elements from another instance.
Retrieve normalization factor for each star.
Retrieve archive elements associated with each stamp.
Retrieve Gaia IDs for each star.
Retrieve Gaia G-band magnitudes for each star.
Retrieve star images.
Retrieve the fraction of valid pixels within the normalization annulus for each star.
index
(value, [start, [stop]])Raises ValueError if the value is not present.
initAndNormalize
(starStamps, innerRadius, ...)Normalize a set of bright star stamps and initialize a BrightStarStamps instance.
readFits
(filename)Build an instance of this class from a file.
readFitsWithOptions
(filename, options)Build an instance of this class with options.
selectByMag
([magMin, magMax])Return the subset of bright star stamps for objects with specified magnitude cuts (in Gaia G).
writeFits
(filename)Write this object to a file.
Attributes Documentation
- metadata¶
Methods Documentation
- append(item, innerRadius=None, outerRadius=None)¶
Add an additional bright star stamp.
- Parameters:
- item
BrightStarStamp
Bright star stamp to append.
- innerRadius
int
, optional Inner radius value, in pixels. This and
outerRadius
define the annulus used to compute the"annularFlux"
values within eachBrightStarStamp
.- outerRadius
int
, optional Outer radius value, in pixels. This and
innerRadius
define the annulus used to compute the"annularFlux"
values within eachBrightStarStamp
.
- item
- count(value) integer -- return number of occurrences of value ¶
- extend(bss)¶
Extend BrightStarStamps instance by appending elements from another instance.
- Parameters:
- bss
BrightStarStamps
Other instance to concatenate.
- bss
- getAnnularFluxes()¶
Retrieve normalization factor for each star.
These are computed by integrating the flux in annulus centered on the bright star, far enough from center to be beyond most severe ghosts and saturation. The inner and outer radii that define the annulus can be recovered from the metadata.
- getArchiveElements()¶
Retrieve archive elements associated with each stamp.
- Returns:
- archiveElements
- getMagnitudes()¶
Retrieve Gaia G-band magnitudes for each star.
- getPositions()¶
- getValidPixelsFraction()¶
Retrieve the fraction of valid pixels within the normalization annulus for each star.
- index(value[, start[, stop]]) integer -- return first index of value. ¶
Raises ValueError if the value is not present.
Supporting start and stop arguments is optional, but recommended.
- classmethod initAndNormalize(starStamps, innerRadius, outerRadius, nb90Rots=None, metadata=None, use_mask=True, use_variance=False, use_archive=False, imCenter=None, discardNanFluxObjects=True, forceFindFlux=False, statsControl=<lsst.afw.math.StatisticsControl object>, statsFlag=<Property.MEAN: 4>, badMaskPlanes=('BAD', 'SAT', 'NO_DATA'))¶
Normalize a set of bright star stamps and initialize a BrightStarStamps instance.
Since the center of bright stars are saturated and/or heavily affected by ghosts, we measure their flux in an annulus with a large enough inner radius to avoid the most severe ghosts and contain enough non-saturated pixels.
- Parameters:
- starStamps
collections.abc.Sequence
[BrightStarStamp
] Sequence of star stamps. Cannot contain both normalized and unnormalized stamps.
- innerRadius
int
Inner radius value, in pixels. This and
outerRadius
define the annulus used to compute the"annularFlux"
values within eachstarStamp
.- outerRadius
int
Outer radius value, in pixels. This and
innerRadius
define the annulus used to compute the"annularFlux"
values within eachstarStamp
.- nb90Rots
int
, optional Number of 90 degree rotations required to compensate for detector orientation.
- metadata
PropertyList
, optional Metadata associated with the bright stars.
- use_mask
bool
- use_variance
bool
If
True
read and write variance data. DefaultFalse
.- use_archive
bool
If
True
read and write an Archive that contains a Persistable associated with each stamp. In the case of bright stars, this is usually aTransformPoint2ToPoint2
, used to warp each stamp to the same pixel grid before stacking.- imCenter
collections.abc.Sequence
, optional Center of the object, in pixels. If not provided, the center of the first stamp’s pixel grid will be used.
- discardNanFluxObjects
bool
Whether objects with NaN annular flux should be discarded. If False, these objects will not be normalized.
- forceFindFlux
bool
Whether to try to find the flux of objects with NaN annular flux at a different annulus.
- statsControl
StatisticsControl
, optional StatisticsControl to be used when computing flux over all pixels within the annulus.
- statsFlag
Property
, optional statsFlag to be passed on to
~lsst.afw.math.makeStatistics
to compute annularFlux. Defaults to a simple MEAN.- badMaskPlanes
collections.abc.Collection
[str
] Collection of mask planes to ignore when computing annularFlux.
- starStamps
- Raises:
- ValueError
Raised if one of the star stamps provided does not contain the required keys.
- AttributeError
Raised if there is a mix-and-match of normalized and unnormalized stamps, stamps normalized with different annulus definitions, or if stamps are to be normalized but annular radii were not provided.
- classmethod readFits(filename)¶
Build an instance of this class from a file.
- Parameters:
- filename
str
Name of the file to read.
- filename
- classmethod readFitsWithOptions(filename, options)¶
Build an instance of this class with options.
- Parameters:
- filename
str
Name of the file to read.
- options
PropertyList
Collection of metadata parameters.
- filename
- selectByMag(magMin=None, magMax=None)¶
Return the subset of bright star stamps for objects with specified magnitude cuts (in Gaia G).