Title The internal structure of the BHR71 outlow
Pi    F.Gueth 
Time   65 hrs
1. Name: The internal structure of the BHR71 outlow

    Authors: F.Gueth

 2. Science goal: Detailed study of the CO and SiO line emission in an
    extremely young (Class 0) protostellar outflow, such as BHR 71.
    The goal is to i) study the internal structure and formation
    mechanism of the outflow using a flow (CO) and shock (SiO) tracer,
    and ii) investigate the physical conditions of the emitting gas by
    multi-transition analysis. The observing strategy is therefore to
    map the outflow in three different transitions, at the same
    angular resolution. This could require a different configuration
    to be used for each line. Mosaicing as well as short-spacings
    measurements are definitely required.

3. Number of sources: 1

4. Coordinates: 

  4.1. RA = 11:59, DEC= -64:52

  4.2. Moving target: no

  4.3. Time critical: no

5.  Spatial scales:

  5.1. Angular resolution: 1 arcsec 
       
  5.2. Range of spatial scales: 1" to 10'
       FOV: 2' x 10' 

  5.3. Single dish: yes
 
  5.4. ACA: yes

  5.5. Subarrays: no
 
6. Frequencies:

a)  6.1. Receiver band: Band 3
    6.2. Line: CO 1-0 
    6.3. Spectral resolution (km/s): 1.0 km/s
    6.4. Spectral coverage (km/s or GHz): 30 km/s    

b)  6.1. Receiver band: Band 6
    6.2. Line: CO 2-1
    6.3. Spectral resolution (km/s): 1.0 km/s
    6.4. Spectral coverage (km/s or GHz): 30 km/s    

c)  6.1. Receiver band: Band 7
    6.2. Line: CO 3-2 
    6.3. Spectral resolution (km/s): 1.0 km/s
    6.4. Spectral coverage (km/s or GHz): 30 km/s    


d)  6.1. Receiver band: Band 3
    6.2. Line: SiO 2-1
    6.3. Spectral resolution (km/s): 1.0 km/s
    6.4. Spectral coverage (km/s or GHz): 30 km/s    

e)  6.1. Receiver band: Band 6
    6.2. Line: SiO 5-4
    6.3. Spectral resolution (km/s): 1.0 km/s
    6.4. Spectral coverage (km/s or GHz): 30 km/s    

f)  6.1. Receiver band: Band 7
    6.2. Line: SiO 8-7
    6.3. Spectral resolution (km/s): 1.0 km/s
    6.4. Spectral coverage (km/s or GHz): 30 km/s    


7. Continuum flux density:

  7.1. Typical value: total flux of a few Jy, but spread over 2'

  7.2. Continuum peak value: unkwown

  7.3. Required continuum rms: probably < 0.1 mJy/b 

  7.4. Dynamic range in image: >10 at all frequencies


8. Line intensity:

  8.1. Typical value: up to 10 K for CO, 0.5 (or less) K for SiO

  8.2. Required rms per channel: 0.3 K for CO, 0.05 K for SiO
  
  8.3. Spectral dynamic range: 10

9. Polarization: no

10. Integration time

Integration time are computed for a 1 km/s velocity resolution
and a 2 arcsec angular resolution. The number of fields
corresponds to a 2 x 10 arcmin field of view, assuming half-power
primary beam overlap.  The increase of sensitivity provided by the
overlap of adjacent beams has not been taken into account.

    a) 4  x 20 fields mosaic
       300 s per field to obtain 0.1 K rms

    b) 8  x 40 fields mosaic
       60 s per field to obtain 0.06 K rms

    c) 12 x 64 fields mosaic
       60 s per field to obtain 0.04 K rms

    d) 3 x 16 fields mosaic
       600 s per field to obtain 0.1 K rms

    e) 8 x 40 fields mosaic
       100 s per field to obtain 0.05 K rms

    f) 12 x 64 fields mosaic
       100 s per field to obtain 0.03 K rms

    Total:
    a) 7 h
    b) 6 h
    c) 13 h
    d) 8 h
    e) 9 h
    f) 22 h

11. Total integration time for program: 65 hr on source with ALMA +
overheads (pointing etc).

Short spacings will be obtained with ACA (240 h observations) and 
single-dish (960h total observations, eg 240h with 4 antennas or
15h with 64 antennas). 



Notes

Number of fields in each mosaics are estimated with half-power
overlaps bewteen adjacent fields. For larges mosaic, we should be able
to use OTF mosaicing.

Before starting this program, it would be wise to have a couple of
single-dish observations of each line, in order to get a good
estimate of the lines intensities, and thus optimize the integration
time.

*********************************************************************

Review Munetake Momose:
Science scope is OK, but time estimate for SiO lines seems to be 
significantly underestimated. According to the ALMA sensitivity 
calculator, the resultant rms levels in line brightness for the 
quoted integration time are

d) SiO(2-1)@86.8GHz : 0.33 K if T=600 sec, 
e) SiO(5-4)@217.1GHz : 0.197K if T=100sec, 
f) SiO(8-7)@347.3GHz : 0.129K if T=100sec. 
(when the resolution is 1" and  dV=1km/s.)

Even if one takes into account the factor of ¥sqrt(2) improvement in 
a mosaicked map, the above rms levels do not fulfill the requirement 
(0.05 K). The correct estimates to achieve 0.1K rms in the SiO(2-1) 
map and 0.05K in the SiO(5-4)/(8-7) maps may be 

d) 3000 sec. per field (0.15K in rms) or 40 hr in total,
e) 800 sec. per field (0.07K in rms) or 71 hr in total, 
f) 350 sec, per field (0,07K in rms) or 75 hr in total.

Therefore the total integration time to observe both the CO and SiO 
lines may be 212 hours. 


Reply Gueth:

Concerning SiO: in fact, in order to avoid too long an observing time,
I computed the integration times with a 2" beam (not a 1" as assumed
by Munetake). I'm sorry for the confusion.  I have updated section 10.
the section 10 as follows: Note that I also updated the numbers for
CO, which were too pessimistic.

Comment Ewine: new DRSP is now baseline

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Review v2.0:
 
2.2.10 Gueth The intenal structure of the BHR71 outflow

This project appears fine as written.