1. Solar Radio Recombination Lines

Arnold O. Benz, Christoph Keller

2. Clark et al. (1995) have reported the detection of the H19-alpha line
in the 350?m band. No line in the millimeter band has been detected
yet in the solarmillimeter or sub-mm radiation. The extremely high
sensitivity of ALMA and its spatial resolution may help to discovered
them. Their detection would represent direct verification of
dielectronic recombination processes in the low corona and transition
region, and would offer the unique possibility of measuring the
magnetic field strength in those regions through the Zeeman effect.

3. Number of sources:                 one

4. Coordinates:           Follow solar orbital motion and solar rotation
                          ecliptic, i.e. +- 23 degrees declination
                          moving target !
    Time critical:  no

 5. Spatial scales:

      5.1. Angular resolution (arcsec):             better than  0.1"

      5.2. Range of spatial scales/FOV (arcsec):                small mosaic
           (optional: indicate whether single-field, small mosaic, 
            wide-field mosaic...)

      5.3. Single dish total power data: yes/no                    yes
      5.4. ACA: yes/no                                     if available

      5.5. Subarrays: yes/no                                             no


   6. Frequencies:

      6.1. Receiver band: Band 3, 6, 7, or 9                       6

      6.2. Lines and Frequencies (GHz):                           one line
            
      6.3. Spectral resolution (km/s):                                 0.1 km/s

      6.4. Bandwidth or spectral coverage (km/s or GHz):   1 GHz


   7. Continuum flux density:                                     10^6 Jy

      7.1. Typical value (Jy):
           (take average value of set of objects)                 10^6 Jy

                    
      7.2. Required continuum rms (Jy or K):                   100 Jy

      7.3. Dynamic range within image:                            10 db


     9. Polarization:  yes/no  (optional)                            yes


   10. Integration time for each observing mode/receiver setting (hr): 1 second

   11. Total integration time for program (hr):                   10 hr

   12. Comments on observing strategy: Start with short observing
periods to test feasibility

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