ADxMeasurement¶
-
class
lsst.validate.drp.calcsrd.
ADxMeasurement
(x, matchedDataset, amx, bandpass, specName, verbose=False, job=None, linkedBlobs=None, metricYamlDoc=None, metricYamlPath=None)[source]¶ Bases:
lsst.validate.drp.base.MeasurementBase
Measurement of AFx (x=1,2,3): The maximum fraction of astrometric distances which deviate by more than ADx milliarcsec (see AMx) (%).
Parameters: x : int
Variant of AMx metric (x=1, 2, 3), which in turn sets the radius of the annulus for selecting pairs of stars.
matchedDataset : lsst.validate.drp.matchreduce.MatchedMultiVisitDataset
amx :
lsst.validate.drp.calcsrd.AMxMeasurement
And AMx measurement, providing the median astrometric scatter in the annulus.
bandpass : str
Bandpass (filter name) used in this measurement (e.g., ‘r’).
specName : str
Name of a specification level to measure against (e.g., design, minimum, stretch).
verbose : bool, optional
Output additional information on the analysis steps.
job :
lsst.validate.drp.base.Job
, optionalIf provided, the measurement will register itself with the Job object.
linkedBlobs : dict, optional
A dict of additional blobs (subclasses of BlobBase) that can provide additional context to the measurement, though aren’t direct dependencies of the computation (e.g., `matchedDataset).
Raises: ValueError
If x isn’t in [1, 2, 3].
Notes
This table below is provided
validate_drp
‘smetrics.yaml
.LPM-17 dated 2011-07-06
- Specification:
- The rms of the astrometric distance distribution for stellar pairs with separation of D arcmin (repeatability) will not exceed AMx milliarcsec (median distribution for a large number of sources). No more than AFx % of the sample will deviate by more than ADx milliarcsec from the median. AMx, AFx, and ADx are specified for D=5, 20 and 200 arcmin for x= 1, 2, and 3, in the same order (Table 18).
The three selected characteristic distances reflect the size of an individual sensor, a raft, and the camera. The required median astrometric precision is driven by the desire to achieve a proper motion accuracy of 0.2 mas/yr and parallax accuracy of 1.0 mas over the course of the survey. These two requirements correspond to relative astrometric precision for a single image of 10 mas (per coordinate).
Astrometric Repeatability Specification Metric Design Minimum Stretch AM1 (milliarcsec) 10 20 5 AF1 (%) 10 20 5 AD1 (milliarcsec) 20 40 10 AM2 (milliarcsec) 10 20 5 AF2 (%) 10 20 5 AD2 (milliarcsec) 20 40 10 AM3 (milliarcsec) 15 30 10 AF3 (%) 10 20 5 AD3 (milliarcsec) 30 50 20 Table 18: The specifications for astrometric precision. The three blocks of values correspond to D=5, 20 and 200 arcmin, and to astrometric measurements performed in the r and i bands.
Attributes Summary
label
metric
units
value
Attributes Documentation
-
label
= 'ADx'¶
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metric
= None¶
-
units
= ''¶
-
value
= None¶