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Hermes DRS
6.0
reduction software
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Hermes DRS
6.0
reduction software
|
Estimates the Background level between spectral orders. More...
Public Member Functions | |
| def | __init__ |
| Make a Hermes component and initialize variables. | |
| def | getName |
| give component name | |
| def | optionsAreValid |
| check options before running | |
| def | __call__ |
| program runs this | |
 Public Member Functions inherited from hermes.pipeline.core.pipelinecomponent.PipelineComponent | |
| def | __init__ |
| def | __call__ |
| def | optionsAreValid |
| def | getOptions |
| def | setOptions |
| def | checkExistShapeUnits |
| def | isOption |
Public Attributes | |
| allowedDistance | |
| user may specify an allowed distance, default is 0.02 | |
| halfLengthMedian | |
| default value for falfLengthMedian is 15 | |
| isDebug | |
| User may want intermediary debug files in debug folder. | |
| results | |
| useOrderPositionsFromTemplate | |
| parameter useOrderPositionsFromTemplate is mandatory, program fails without it. More... | |
| Public Attributes inherited from hermes.pipeline.core.pipelinecomponent.PipelineComponent | |
| options | |
| logger | |
| ConsoleLogSeverity | |
| default value | |
| canShowGraphics | |
| when machine does not run matplotlib. More... | |
Estimates the Background level between spectral orders.
PURPOSE :
This module estimates the background level at positions mid-between the
spectral orders from the intensity values nearby this positions. The
applied algorithm takes care of the facts that
(a) the intensity increases towards the orders, possibly over a scale
that is not very large relative to the pixel size;
(b) hot pixels, dark pixels and radiation events may have biased observed
intensities locally;
(c) further model-fitting requires relatively smooth input data for a
successful interpolation of the background near and under the spectral
orders.
With the cross-disperser being a prism, the spectral order at longer
wavelength are packed closer together. The background level between successive
spectral orders tends to change faster when the spectral orders are packed more
densely. It is then advantageous to fit a model not in the detector pixel
coordinates, but in a coordinate system linked to the number of the spectral
order, i.e. varying between the centre of order m and order m + 1 smoothly
from m to m + 1 proportional with the distance from the centres of the spectral
orders. Hence, first this 'relative background coordinate system' is set-up
and thereafter, using data on pixels with are sufficiently close to m + 1/2,
the background at m + 1/2 is estimated in each row.
An estimate of the random error in the background grid-points is included.
COMMENTS :
None
SYNTAX :
INPUT CONSTANTS FROM INSTRUMENT MODEL :
if not in RESULTDICT :
estimateOrderPositionTemplate is taken from model
INPUT DATA FROM RESULTDICT :
MANDATORY :
image : input image (output from subtractbiasCCD)
OPTIONAL :
estimateOrderPositionTemplate
OPTIONS READ FROM OPTIONDICT :
MANDATORY :
useOrderPositionsFromTemplate : YES or NO
If order positions are NOT measured on frame,
see if we may use the template. If not, stop
with message.
OPTIONAL :
allowedDistance :
allowed distance is the maximum allowed
distance, along a row, between a pixel
and the mid-interorder position in that row
expressed in the "relative background"
coordinate system (order separation = 1).
Value very critical for results, see COMMENTS.
halfLengthMedian :
default = 15
isDebug (Boolean : True or False)
default value : False
writes results to two fits files
image in 'T10image.fits')
imageVariance in 'T11imageVariance.fits')
OUTPUT WRITTEN TO THE RESULTDICT:
backgroundOrderPositions = imageBackcoord
measureBkgResultFile = path + filename1
midInterorderBackground = meds | hermes.pipeline.components.measurebackground.measureBackground.useOrderPositionsFromTemplate |
parameter useOrderPositionsFromTemplate is mandatory, program fails without it.
1.8.6