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The visir_util_convert_pos recipe

visir_util_convert_pos

Synopsis

Conversion of object position(s) from matching pairs of nodded object files + sextractor tables

Description

The files listed in the Set Of Frames (sof-file) must be tagged: Sextractor-object-file.fits POS_CONVERT Sextractor-table-file.fits POS_TABLE The table must include these columns, all with numerical data: XWIN_IMAGE, YWIN_IMAGE, FLUX_AUTO.

Such a table can be created by the source extractor software sextractor.

In addition to containing pairs of object- and table-files the SOF may also contain only object-files.

In this case the object files must be tagged with: POS_CONVERT.

For each input object frame one or more products will be created with updated WCS-ccordinates (CRPIX[12]).

When the object frame is matched with a table-frame, one product will be created for each row in the table.

Such products will be created in order of decreasing object brightness.

When the object frames are pairs of 4-beam-frames, the position (centroid) of the brightest object in the 4-beam-frame will be written into the first product.

The nodding and chopping throw will determine the position written into the second product based on the raw-frame and the position written into the two products based on the matching off-frame.

When the object frames are pairs of 4-beam-frames, the recipe also supports updating the WCS-coordinates of an auxiliary frame (e.g. error map) for each object.

If present these auxiliary frames must be tagged: Object-auxiliary.fits POS_AUX (optional).

The primary product(s) will have a FITS card ‘HIERARCH ESO PRO CATG’ with a value of: IMG_CONVERTED If created, the auxiliary products will have a FITS card ‘HIERARCH ESO PRO CATG’ with a value of: AUX_CONVERTED

Constructor

cpl.Recipe("visir_util_convert_pos")

Create an object for the recipe visir_util_convert_pos.

import cpl
visir_util_convert_pos = cpl.Recipe("visir_util_convert_pos")

Parameters

visir_util_convert_pos.param.eccmax

The maximum eccentricity allowed in the combination of the three (in parallel nod/chopping) or four (in perpendicular nod/chopping) beams. In parallel mode, three perfectly aligned points spaced with the chopnod throw will have eccentricity 0, while in perpedicular mode a square with the chopnod throw as the side length will have eccentricity 0 (float; default: 0.25) [default=0.25].

visir_util_convert_pos.param.naverage

Number of plains to average before searching for the beam positions. (long; default: 1) [default=1].

visir_util_convert_pos.param.xcorrelate

Shift beam positions by cross correlating images. (bool; default: False) [default=False].

visir_util_convert_pos.param.brightest

Shift beam positions by brightest pixel. (bool; default: True) [default=True].

visir_util_convert_pos.param.window

Window around detected beams to use for cross correlation. (long; default: 64) [default=64].

The following code snippet shows the default settings for the available parameters.

import cpl
visir_util_convert_pos = cpl.Recipe("visir_util_convert_pos")

visir_util_convert_pos.param.eccmax = 0.25
visir_util_convert_pos.param.naverage = 1
visir_util_convert_pos.param.xcorrelate = False
visir_util_convert_pos.param.brightest = True
visir_util_convert_pos.param.window = 64

You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:

import cpl
visir_util_convert_pos = cpl.Recipe("visir_util_convert_pos")
[...]
res = visir_util_convert_pos( ..., param = {"eccmax":0.25, "naverage":1})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

Please report any problems to Lars Lundin. Alternatively, you may send a report to the ESO User Support Department.