What's the difference between Antenna1 and Antenna2? Axis definitions in plotms: Difference between revisions
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== Frequency == | == Frequency == | ||
Frequency in units of GHz. | Frequency in units of GHz. | ||
??? | |||
What frequency is this exactly? It does not appear to change with the parameters in the '''Trans''' tab of [[plotms]]. | |||
??? | |||
== Corr == | == Corr == | ||
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== U, V, W == | == U, V, W == | ||
''u'', ''v'', and ''w'' in units of meters | |||
??? | |||
Is this true about the units? Clearly it is in the same units as UVDist | |||
??? | |||
== Velocity == | == Velocity == | ||
Velocity, which can be defined by parameters in the '''Trans''' tab of [[plotms]]. | |||
== Amp == | == Amp == |
Revision as of 04:13, 19 February 2010
Plotms is a powerful tool for visualizing your measurement set, and provides you with lots of choices for X- and Y- Axes. It's not always clear what the choices mean, so below are some explanations.
Scan
The scan number, as listed by listobs.
Field
The field number, as listed by listobs. Typically, each source should have a different field number.
Time
The time at which the visibility was observed, given in terms of calendar year (yyyy/mm/dd/hh:mm:ss.ss)
Time_interval
???
Is this integration time?? In what units??
???
Spw
The spectral window number (analogous to what VLA users know as an IF). The characteristics of each spectral window are listed in listobs.
Channel
The frequency channel number.
Frequency
Frequency in units of GHz.
???
What frequency is this exactly? It does not appear to change with the parameters in the Trans tab of plotms.
???
Corr
Correlations (e.g., RR, LL), which have been assigned integer IDs
???
By what scheme???
How can one find out what integer corresponds to which correlation???
Antenna1, Antenna2
For plotting baseline-based quantities like amplitude, either Antenna1 or Antenna2 must be chosen. Antenna1 is the first antenna in a baseline pair; for example, for baseline 2-4, Antenna1 = 2. Antenna2 is the second antenna in a baseline pair; for example, for baseline 2-4, Antenna2 = 4. Antennae are numbered according to the antenna IDs listed in listobs.
Antenna
For plotting antenna-based quantities like elevation, use just plain Antenna. Antennae are numbered according to the antenna IDs listed in listobs.
Baseline
The baseline number, where baseline number is defined as ???
???
UVDist, UVDist_L
Projected baseline separations. UVDist is in units of meters, while UVDist_L is in units of the observing wavelength (lambda, not kilolambda).
???
Is this true about UVDist and meters?
???
U, V, W
u, v, and w in units of meters
???
Is this true about the units? Clearly it is in the same units as UVDist
???
Velocity
Velocity, which can be defined by parameters in the Trans tab of plotms.
Amp
Data amplitudes in units of Jansky.
Phase
Data phases in units of degrees.
Real, Imag
The real and imaginary parts of the visibility in units of Jansky.
Flag
Azimuth
Elevation
HourAngle
ParAngle
Ant-Azimuth
Ant-Elevation
Ant-ParAng
Row
FlagRow
Last checked in CASA Version 3.0.1 (r10380).