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NRAO Home > CASA > CASA Toolkit Reference Manual |
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measures.asbaseline - Function
1.4.1 define a baseline from a position measure
Description
asbaseline converts a position measure into a baseline measure. No actual
baseline is calculated, since operations can be done on positions, with
subtractions to obtain baselines at a later stage.
Arguments
Inputs |
| ||
pos |
| position measure
| |
| allowed: | record |
|
| Default: |
|
|
record
Example
print "\t----\t asbaseline Ex 1 \t----"
####An example of getting baselines with 3 antenna positions
#### Define the frame ; where, which-direction and when
me.doframe(me.observatory(’VLA’))
me.doframe(me.direction(’J2000’, ’19h20m00’, ’20d10m00’))
me.doframe(me.epoch(’utc’, ’2007/07/08/20:30:00’))
##antenna position
ants=me.position(’itrf’,qa.quantity([3828763.11,3828746.55, 3828727.43],’m’), qa.quantity([442449.106,442592.14, 442580.12],’m’), qa.quantity([5064923.01, 5064923.01, 5064923.51],’m’))
print ants
#{’type’: ’position’, ’refer’: ’ITRF’, ’m1’: {’value’: array([ 0.92031276, 0.92031276, 0.92031535]), ’unit’: ’rad’},
#’m0’: {’value’: array([ 0.11504897, 0.11508633, 0.1150838 ]), ’unit’: ’rad’},
#’m2’: {’value’: array([ 6364639.28758924, 6364639.27051283, 6364627.33064587]), ’unit’: ’m’}}
bl=me.asbaseline(ants)
print bl
#{’type’: ’baseline’, ’refer’: ’J2000’, ’m1’: {’value’: array([ 0.92068328, 0.92068326, 0.92068585]), ’unit’: ’rad’},
#’m0’: {’value’: array([-2.08658811, -2.08655073, -2.08655326]), ’unit’: ’rad’},
#’m2’: {’value’: array([ 6364639.28758924, 6364639.27051283, 6364627.33064587]), ’unit’: ’m’}}
me.expand(bl)
#{’return’: {’m0’: {’unit’: ’rad’,
# ’value’: array([-0.51637894, -0.36575235, 1.50036599])},
# ’m1’: {’unit’: ’rad’,
# ’value’: array([-0.00060966, 0.00302388, 0.02206414])},
# ’m2’: {’unit’: ’m’,
# ’value’: array([ 143.98943974, 135.78652583, 22.58992696])},
# ’refer’: ’J2000’,
# ’type’: ’baseline’},
# ’xyz’: {’unit’: ’m’,
# ’value’: array([ 1.25215025e+02, -7.10925354e+01, -8.77850493e-02,
# 1.26804339e+02, -4.85640980e+01, 4.10601842e-01,
# 1.58931410e+00, 2.25284374e+01, 4.98386892e-01])}}
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Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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