Title  Chiron distant activity
Pi   D. Bockelee-Morvan  
Time  5 hr 

1. Name of program and authors 
   Chiron distant activity 
   Authors: D. Bockelee-Morvan, N. Biver, J. Crovisier, J. Boissier 
 
2. One short paragraph with science goal(s) 
   (2060) Chiron is a Centaur which orbits around the Sun between  
   8.5 and 18.9 AU and presents cometary-like activity, with a well developed 
   dust coma and frequent outbursts. CO outgassing is likely at the origin 
   of this activity, while CN is the only gaseous species detected in 
   the coma. We propose to search for the CO J(2-1) and HCN J(1-0) lines with 
   unprecedented sensitivity with ALMA. 
 
3. Number of sources  
   1 
    
4. Coordinates: 
 
4.1. Rough RA and DEC  
     
 
4.2. Moving target: yes 
 
4.3. Time critical: no 
 
4.4. Scheduling constraints:  
 
5. Spatial scales: 
 
5.1. Angular resolution (arcsec): 
       
     Compact configuration (1-2 arcsec) or single-dish 
     
 
5.2. Range of spatial scales/FOV (arcsec): 
  
5.3. Required pointing accuracy: (arcsec) 
     0.5" 
 
6. Observational setup 
 
6.1. Single dish total power data: beneficial 
 
     Observing modes for single dish total power:  
     frequency switch 
 
6.2. Stand-alone ACA: no 
 
6.3. Cross-correlation of 7m ACA and 12m baseline-ALMA antennas:  
     no  
 
6.4. Subarrays of 12m baseline-ALMA antennas: no 
 
 
7. Frequencies: 
 
7.1. Receiver band: 3, 6 
 
7.2. Lines and Frequencies (GHz):  
      
     CO (2-1) 
      
 
7.3. Spectral resolution (km/s): < 0.05 km/s 
 
7.4. Bandwidth or spectral coverage (km/s or GHz): 
     20 km/s 
 
8. Continuum flux density:  
 
9. Line intensity 
 
9.1. Typical value (K or Jy): ? 
      
 
9.2. Required rms per channel (K or Jy):  
     0.0015 K km/s over 0.1 km/s in single-dish mode at 230 GHz 
 
9.3. Spectral dynamic range: 
 
9.4. Calibration requirements: absolute      (10%) 
                               repeatability (10%) 
                               relative      (10%) 
 
10. Polarization: no  
 
 
11. Integration time for each observing mode/receiver setting (hr): 
     
 
12. Total integration time for program (hr):  
    5 hr 
 
13. Comments on observing strategy :  
     
 
 
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Review v2.0:
 
Review of 4.3.1-4.3.9

These projects have all been updated to v2.0 and a new, timely project
on D/H has been added.

One issue that all projects share is their use of the ACA in
crosscorrelation with the ALMA-12m antennas. Are the common baselines
really essential, or would *simultaneous* (but standalone) ACA
observations also work? This might be much easier on the system
(slewing times; correlator; ...). Fully standalone (and therefore
separate in time) ACA observations for comets obviously make little
sense (...although, one could think of cases where some large-scale
monitoring could be useful). 

Comment: the integration times do not seem to be worked out in much
detail, although the total times listed seem of the correct
magnitude. This may be the best that is currently feasible. (cf. v1.1
where more detailed estimates are given).