Title  Io's volcanism 
Pi      E. Lellouch
Time   100 hrs


1. Name of program and authors
Title:  Io's volcanism 
Authors: E. Lellouch

2. One short paragraph with science goal(s)

Abstract: Io's atmosphere is dominated by active volcanism that directly
   injects species like SO2, SO, NaCl into the atmosphere. This
   atmosphere shows unique spatial and temporal variability, which remains
   poorly characterized. ALMA can map the detected species, measure Doppler
   shifts that are due to planetary-wide circulation regimes, to plasma
   interactions, or to volcanic plume injection, and search for many new potential 
   atmospheric molecules (OCS, S2O, KCl, Cl0...) as well as determine chlorine and sulfur isotopic
   ratios. All this bears implications on the composition of ionian
   lavae, magmas and interior. 

3. Number of sources : 1
   
   Io (satellite)


4. Coordinates:

4.1. Rough RA and DEC 

     variable

4.2. Moving target: yes. Satellite ephemerides need to be implemented.

4.3. Time critical: yes (need to observe Io sufficiently away from Jupiter)

4.4. Scheduling constraints: (optional)
	

5. Spatial scales:

5.1. Angular resolution (arcsec): 0.2" 

5.2. Range of spatial scales/FOV (arcsec): 1.2" 

     (optional: indicate whether single-field, small mosaic,
     wide-field mosaic...)

5.3. Required pointing accuracy: 0.2"


6. Observational setup

6.1. Single dish total power data: no

     Observing modes for single dish total power:

     (e.g., nutator switch; frequency switch; position switch;
     on-the-fly mapping; and combinations of the above)

6.2. Stand-alone ACA: no

6.3. Cross-correlation of 7m ACA and 12m baseline-ALMA antennas: 
     beneficial

6.4. Subarrays of 12m baseline-ALMA antennas: no


7. Frequencies:

7.1. Receiver band: Band 6, 7

7.2. Lines and Frequencies (GHz): 

    Many lines at 1.3 mm and 0.8 mm

7.3. Spectral resolution (km/s): 0.05 km/s 

7.4. Bandwidth or spectral coverage (km/s or GHz): 30 km/s is sufficient to
correct for orbital motions of Io. Large bandwidth (up to several GHz) is 
desirable to optimize serendipitous line searches. 

8. Continuum flux density:

8.1. Typical value (Jy): 100 K

     (take average value of set of objects)
     (optional: provide range of fluxes for set of objects)

8.2. Required continuum rms (Jy or K): 0.1 K

8.3. Dynamic range within image:

     (from 7.1 and 7.2, but also indicate whether, e.g., weak objects
     next to bright objects)

8.4. Calibration requirements: absolute       10 % 
                               repeatability  5 % 
                               relative       5 % 


9. Line intensity:

9.1. Typical value (K or Jy): 2 K - 30 K

     (take average value of set of objects)
     (optional: provide range of values for set of objects)

9.2. Required rms per channel (K or Jy): 0.5 K

9.3. Spectral dynamic range:

9.4. Calibration requirements: absolute       5 % 
                               repeatability  1-3% 
                               relative       1-3% 


10. Polarization: no 

10.1. Required Stokes parameters:

10.2. Total polarized flux density (Jy):

10.3. Required polarization rms and/or dynamic range:

10.4. Polarization fidelity:

10.5. Required calibration accuracy:


11. Integration time for each observing mode/receiver setting (hr):
Typically 10 hours per line.


12. Total integration time for program (hr):
About 100 hours 



13. Comments on observing strategy : (optional)

    (e.g. line surveys, Target of Opportunity, Sun, ...):

If a volcanic "event" occurs, it could be a ToO.
--------------------------------------------------
Review v2.0:
 
Review 4.1.1-4.1.8

The only question I have with regards to these projects is the use of
ACA cross-correlated with ALMA-12m. Several projects list this option
as 'required' or as 'beneficial', but no arguments are given. 

- When listed as 'required' does this mean that the observations are
  mosaics, and that the ACA is needed to provide the intermediate
  scales? If so, are the cross-correlations with the ALMA-12m antennas
  needed, or could simultaneous ACA-7m-only observations also suffice?

- When listed as 'beneficial' is this purely for S/N reasons or also
  for uv-coverage? The cross-correlation option is fairly demanding on
  the scheduling, and unlikely to be used unless absolutely necessary.