Stringency Tool stringency.g

download stringency.g
download almatau.g
download site database

The stringency tool asks the question: how much time is available for which the opacity, phase stability, and wind velocity are better than some specified values. Actually, the stringency is one over the fraction of time the conditions surpass the stated limits, so a stringency of 20 indicates such conditions are available only 5% of the time.

The stringency tool requires that a database of site data is available, and also that almatau.g is available to scale the 225 GHz opacity to its appropriate value at the observing frequency. Currently, there is only a linear scaling of the rms phase errors with frequency, though a correction for the dispersive phase in the submillimeter wavelength regime would be a more accurate way to go.

Note that the stringency is a strong function of elevation for high frequency observations.

In the future, we will add:

• calculation of residual phase errors given the phase calibration method (ie, fast switching, WVR, or none).
• limits for the temperature gradient in the stringency calculation
• inclusion of an LST range, the posibility of restricting the observing to night time, or restricting to certain months of the year.
• it has been requested that inclusion of array reconfiguration be included in the stringency calculation. Such software has been developed in a different context, and we may include that in the stringency development.

To run the stringency tool, you will need to

download stringency.g
download almatau.g
download site database
start aips++ in the same directory
at the aips++ prompt, type:

  include 'stringency.g'                 # define the stringency tool
  st := stringency();                    # create st, a stringency tools
  st.read (filename='database_1996-2001.ascii')  # read site data
  st.setobs (freq=345, el=60)            # set up observations: 345 Ghz, 
                                         #    60deg elevation angle
  st.setphasecal (method='none')         # no phase cal methods recognized yet
  st.setphaselength (length=50)          # but a baseline length is recognized
  st.calc (tau=0.1, phase=40, wind=10)   # stringency for tau(345) < .1,
                                         #    rms phase(345) < 40 deg, 
                                         #    wind < 10m/s
  st.calc (tau=0.1, phase=30, wind=10)
  st.calc (tau=0.1, phase=20, wind=10)
  st.calc (tau=0.1, phase=20, wind=10)
  st.calc (tau=0.1, phase=20, wind=5)
  st.calc (tau=0.1, phase=20, wind=2.5)
  st.done()                              # delete that stringency tool

Last Modified 2003 July 2