Opacity Curves at the HHT

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Opacity Curves at the HHT

To get a sense of what conditions are required for a particular project, we present some atmospheric transmission plots for various tau(225 GHz) at the HHT.

     

  1. Tau(225 GHz) = 0.050
  2. Tau(225 GHz) = 0.075
  3. Tau(225 GHz) = 0.100
  4. Tau(225 GHz) = 0.125
  5. Tau(225 GHz) = 0.150
  6. Tau(225 GHz) = 0.200
  7. Tau(225 GHz) = 0.250
  8. Tau(225 GHz) = 0.300

To estimate the opacity in the different frequency bands accessible at the HHT, you can use the following table:

Opacity for some lines of interest

Spectral Line Frequency (GHz) opacity (tau 225 GHz)
12CO 2-1 230 1 *
12CO 3-2 345 4.4 *
12CO 4-3 460 24.*
[C I] 492 36 *
12CO 6-5 691 34 *
[C I] 809 40 *

Thus, a tau(225 GHz) of 0.05 corresponds to a tau(809GHz) of 2, or a transmission of 0.14 at an airmass of 1.

These numbers are estimates only, since we have not yet calibrated the taumeter 225 GHz values with the theoretical values produced by the atmospheric transmission programs we use to produce the plots.

 Copyright Arizona Radio Observatory.
For problems or questions regarding this web contact [tfolkers{at}as{dot}arizona{dot}edu].
Last updated: 09/04/08.