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measures.todoppler - Function

1.4.1 convert a frequency or radialvelocity measure to a doppler measure


Description

todoppler will convert a radialvelocity measure or a frequency measure to a doppler measure. In the case of a frequency, a rest frequency has to be specified. The type of doppler wanted (e.g. RADIO) has to be specified.

Arguments





Inputs

rf

doppler reference type

allowed:

string

Default:

v0

radial velocity or frequency measure

allowed:

record

Default:

rfq

rest frequency (frequency measure or frequency quantity)

allowed:

any

Default:

variant

Returns
record

Example

 
 
print "\t----\t todoppler Ex 1 \t----"  
f = me.frequency(’lsrk’,’1410MHz’)     # specify a frequency  
print f  
#{’m0’: {’value’: 1410000000.0, ’unit’: ’Hz’},  
# ’refer’: ’LSRK’,  
# ’type’: ’frequency’}  
print me.todoppler(’radio’, f, qa.constants(’HI’)) # give doppler, using HI rest  
#{’m0’: {’value’: 2196249.8401180855, ’unit’: ’m/s’},  
# ’refer’: ’RADIO’,  
# ’type’: ’doppler’}  
 

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