Title  The atmospheres of Triton, Pluto and other transneptunians (TNO) 
Pi     E. Lellouc
Time   432 hrs


1. Name of program and authors
Title: The atmospheres of Triton, Pluto and other transneptunians (TNO) 
Authors: E. Lellouch


2. One short paragraph with science goal(s)
Abstract: Triton and Pluto have detectable tenuous atmospheres
   with ~10 microbar pressure. These primarily N2 atmospheres exhibit
   slow time variation due to volatile migration and surface temperature
   changes. ALMA can search for new species in these atmospheres, in
   particular CO and HCN. Similarly the largest known TNOs, whose sizes
   are ~2000 km, may be able to retain atmospheres, and search for
   CO is warranted. This search could include Pluto's satellite Charon.
   If, as expected, CO is detected on Pluto and Triton, atmospheric circulation
   might be measured from Doppler shifts.

3. Number of sources : ~5-10
   
   Pluto
   Triton
   Charon
   Eris
   2003 EL61 
   2003 FY9

4. Coordinates:

4.1. Rough RA and DEC 

     Variable

4.2. Moving target: yes/no (e.g. comet, planet, ...)

	Yes. Comet-like ephemerides may need to be implemented

4.3. Time critical: yes/no (e.g. SN, GRB, ...)

	No 

4.4. Scheduling constraints: (optional)


5. Spatial scales:


5.1. Angular resolution (arcsec): 0.03-0.1 
Note: In general, the resolution here is not what is required during
   observation, but rather the size of the body, which is
   what is needed for the brightness temp rms calculation.
   These are point source detections - i.e., we don't *want*
   the body resolved (any resolution *worse* than this is OK).
   For Pluto and Triton (0.1" in size), though, a ~0.03" resolution would
   be needed to map CO and investigate winds from Doppler shifts. 

5.2. Range of spatial scales/FOV (arcsec):  FOV = 0.03-0.1

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

5.3. Required pointing accuracy: (arcsec) 0.1


6. Observational setup

6.1. Single dish total power data: no

     Observing modes for single dish total power: wobbler switch

     (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): 

	CO J=2-1 and 3-2
      HCN J=3-2 and 4-3
     
7.3. Spectral resolution (km/s): 0.05

7.4. Bandwidth or spectral coverage (km/s or GHz): 0.5 GHz

8. Continuum flux density:

8.1. Typical value (Jy):
	
	30-40 K
	

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 ( 10% )
                               relative      ( 10% )


9. Line intensity:

9.1. Typical value (K or Jy): 10 K (?) 
    
9.2. Required rms per channel (K or Jy): 1 K

9.3. Spectral dynamic range:

9.4. Calibration requirements: absolute      ( 10% )
                               repeatability ( 10% )
                               relative      ( 10% )

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):

24 hr per planet and line. 

12. Total integration time for program (hr):

432 hr (~3 lines x 6 objects x 24 hours)

13. Comments on observing strategy : 
--------------------------------------------------
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.