Solar Submillimeter-wave Telescope

   Description of SST 212 GHz and 405 GHz real time monitoring

1. Upper plots are in relative units, proportional to the antenna temperatures for the channels 2 (212 GHz) and 5 (405 GHz).
2. Lower plots are scintillation indices for channels 2 and 5, defined as the ratio of the 40 ms data sigma of fluctuations over the solar mean value above the sky level, taken every 3 seconds. Indices are useful for quick detection of:
   
   • a genuine solar pulsating burst;
   • atmospheric transmission fluctuations;
   • system malfunctions.
3. The cluster of six beams, shown in the diagram, is directed to the active region selected for tracking. Tracking is positioned on beam 5.

4. Final corrected antenna temperatures can be determined ONLY after three corrections are made:
   
   • the source actual spatial position with respect to all beams as calculated by comparing the outputs from 212 GHz beams 2,3 and 4;
   • correction for atmosphere transmission, dependent on elevation angle (which are larger at 405 GHz);
   • assignment of baseline levels above which the emission in excess is to be calculated.
5. Plots show calibrations, solar maps, and sky temperature vs. elevation scans (tipping) used to calculate atmosphere opacity. They are useful as qualitative information on the quality of observations and of sky transmission.
6. The comparison of observed antenna temperatures at channels 2, 3 and 4 allows the determination of the source position with respect to them. The antenna temperatures can be then corrected to that position, and 212 GHz, as well as at 405 GHz (channel 5).

      SST Calibrated Data (click here)

• A temporary list of dates is readily available. Other desired dates from 2003 to present can be requested to Pablo Pereyra (ppereyra@casleo.gov.ar).

• The first visualization panels exhibit all six channels in three options:
  

  • all six channels, in corrected antenna temperature, 40 ms data;
  • same as before with data smoothed in one second;
  • in separate panels, in units of ADCs (analog-to-digital counts) and in units of observed antenna temperature for the whole observing period.

• Panels also show:

  • antenna beams positions on the solar disk;
  • atmosphere attenuation.

• ZOOM mode allows clicking at two successive times to obtain the corresponding time-expanded plot.

• "Multiple Beams" mode calculate the corrected Antenna Temperature at position deduced from the comparison of beams 2, 3 and 4 (see description at the main webpage), at 212 GHz and at 405 GHz (assuming the source position is the same at the two frequencies). Attention: When selected time structures do not correspond to bursts, the calculated Antenna Temperature may produce inconsistent results.

• Antenna temperatures are corrected for atmospheric transmission, multiplying by exp [τ/sin H] where τ is the measured optical depth and H the Sun elevation angle at the time closest to the time of analysis.

• Burst excess temperatures, ΔT, above the level previous to the event, are converted into solar flux units: S = 0.62 ΔT (at 405 GHz) and S = 0.35 ΔT (at 212 GHz), for which it has been adopted the latests measured aperture efficiencies (0.20 at 405 GHz and 0.35 at 212 GHz).

    References

• For method descriptions see:
  Georges, C. B. et al., Proc. of SBMO-International Microwave Symposium/Brazil IEEE-MTT Cat. N89th0260-0, p. 447, 1989;
  Giménez de Castro, C. G. et al., Astron. Astrophys., 140, 343, 1999.

• For SST descriptions see:
  Kaufmann, P. et al., Proc. of SPIE, 7012, 7012L-1-8, doi:10.1117/12.788889, 2008