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Basic Information on obsrms
Task: obsrms
Purpose: Calculate theoretical rms for telescope array observations.
Categories: image analysis
OBSRMS - Calculate theoretical rms for telescope array observations.
The MIRIAD task TELEPAR provides typical values for Tsys and Jy/K.
for several observatories.
Key: tsys
SSB system temperature (Kelvin). Default=300 K.
Tsys includes the loss through the atmosphere.
Key: jyperk
Antenna gain in units Jy/K. Default=150 Jy/K.
Key: antdiam
Antenna diameter (m), and aperture efficiency can be used to calculate
jyperk. If only one value is given then the aperture efficiency used
is 0.6. Default=0,0.6 i.e. use jyperk value.
Key: lambda
wavelength in millimeters. Default=3 mm.
Key: freq
freq (GHz) can be used to compute lambda. Default=0 GHz, uses lambda.
Key: theta
Beamsize in arcsec. Two values may be given for the beam FWHM.
If only one value is given it is used for both axes. Default=1,1
Key: nants
Number of antennas in array. Single antenna is OK too. Default=9.
Key: bw
Bandwidth in MHz used for continuum observations. Default=800 MHz.
Key: deltav
Velocity resolution in km/s can be used to compute bandwidth for
spectral line observations. Default=0 km/s, i.e. use bandwidth value.
Key: inttime
Total Integration time on source in minutes. Default=1 minute.
Key: coreta
Correlator efficiency factor. A perfect correlator has coreta=1.
2-, 3-, and 4-level correlators have coreta=0.64, 0.81, and 0.88
respectively. (see Thompson, Moran, and Swenson, p229).
Default=0.88
Key: rmsphase
RMS phase noise (degrees). Phase noise reduces the signal, effectively
increasing the observed RMS noise in the data by a factor
exp(rmsphase(radians)**2/2.). For strong sources atmospheric
phase noise can be removed by selfcalibration.
Default=0. degrees. i.e. perfect data.