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2.4.1 Set the noise level fixed sigma (mode=simplenoise) or Brown’s equation
(mode=calculate)
Description
Set various system parameters from which the thermal (ie, random additive)
noise level will be calculated.
For mode=simplenoise, one specifies the standard deviation for the noise to be added to real and imaginary parts of the visibility.
For mode=calculate, the noise will vary with dish diameter, antenna efficiency, system temperature, opacity, sky temperature, etc. The noise will increase with the airmass if tau is greater than zero. The noise is calculated according to the Brown Equation (ie, R.L. Brown’s calculation of MMA sensitivity, 3Oct95):
![]() | (2.16) |
Arguments
| Inputs |
| ||
| mode |
| Mode of operation. String:
’table’—’simplenoise’—’calculate’
| |
| allowed: | string |
|
| Default: | calculate ’calculate’ | |
| table |
| Name of noise table if not simplenoise or not calculated
| |
| allowed: | string |
|
| Default: | ” | |
| simplenoise |
| Level of noise if not Table or not Calculated
| |
| allowed: | any |
|
| Default: | variant 0.0Jy |
|
| antefficiency |
| antenna efficiency
| |
| allowed: | double | |
| Default: | 0.8 0.8 |
|
| correfficiency |
| Correlation efficiency
| |
| allowed: | double |
|
| Default: | 0.85 0.85 |
|
| spillefficiency |
| Forward spillover efficiency
| |
| allowed: | double |
|
| Default: | 0.85 0.85 |
|
| tau |
| Atmospheric Opacity
| |
| allowed: | double |
|
| Default: | 0.0 0.0 |
|
| trx |
| Receiver temp (ie, all non-atmospheric Tsys
contributions) [K]
| |
| allowed: | double |
|
| Default: | 50 50 |
|
| tatmos |
| Temperature of atmosphere [k]
| |
| allowed: | double |
|
| Default: | 250.0 250.0 |
|
| tcmb |
| Temperature of cosmic microwave background [K]
| |
| allowed: | double |
|
| Default: | 2.7 2.7 |
|
Please send any comments or questions about CASA or AIPS++ to aips2-requests@nrao.edu
Copyright © 2008 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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Updated daily during alpha development.