1. Name: Energetics of the HH 80-81 molecular outflow. Authors: D. Shepherd et al. 2. Science Goal: HH 80-81 is a well-collimated jet powered by an intermediate mass young stellar object with a spectral type later than B1. It is the most massive star which powers a well-collimated, parsec-scale jet similar to those produced by low-mass young stellar objects. The ionized jet has a projected length of about 5 pc (Marti, Rodriguez, & Reipurth 1993; Heathcote et al. 1998). The truncated CO flow (mass ~ 460 Msun) full opening angle is roughly 40 deg and does not re-collimate (Yamashita et al. 1989). The dynamics of the jet suggest that it is a scaled-up version of a T Tauri star jet. The CO flow position angle is misaligned with the jet by roughly 30deg and it is unclear if the observed jet can power the CO flow. However, the only CO measurements that exist were done with less than Nyquist spacing, 15'' resolution, and the authors assumed the emission was optically thin. These factors place a large uncertainty on the known dynamics of the CO flow and its relationship to the ionized jet. To determine the total mass and dynamics in the molecular flow we would like to image the HH 80-81 molecular outflow in three spectral lines (12CO(J=2-1), 13CO(J=2-1), & C18O(J=2-1). The aims are to recover all emission in the flow in the CO isotopes to estimate optical depth and energetics, and trace high velocity emission to specific regions. The continuum emission between 230 & 219 GHz will be used to get the millimeter SED of the driving source(s) as well as other sources detected in the region at 6cm. The mosaic must be sensitive to size scales between 1" and 60" in the outflow, thus, ACA and Total Power measurements are absolutely required to recover the extended emission. Multi-scale reconstruction of the combined uv-data will be needed to generate the final mosaic images. 3. Number of Sources: 1 4. Coordinates: 4.1 Central coordinates: 18 19 12.11 -20 47 30.4 (J2000), (Galactic coordinates: LII= 10.8415 BII= -2.5916) mosaic region: 15'x15' centered on above coordinates 4.2 Moving target: No 4.3 Time Critical: No 5. Spatial Scales: 5.1 Angular Resolution: 1" 5.2 Range of spatial scales required: 1" to 60" FOV: 15'x15' 5.3 Single dish: Yes - NOTE: this source is near the galactic plane and in a region rich with CO emission. The Total Power mosaic will likely need to be larger than the interferometer mosaic to ensure that the edge of the mosaic has emission-free regions (required to spatially smooth the image across the scanning direction to remove artifact stripes that may be present due to changes in the atmosphere between observing OFF positions). 5.4 ACA: Yes 5.5 Subarrays: Yes (main array and one to obtain total power data). 6. Frequencies: 6.1 Receiver Band: 6 6.2 Lines: CO(J=2-1), 13CO(J=2-1), C18O(J=2-1) Frequencies (GHz): 230.538, 220.398, 219.560 (lines listed are the main lines of interest, other will also be observed). 6.3 Spectral Resolution (km/s): 0.3 km/s 6.4 Spectral Coverage (km/s or GHz): 200 km/s per line 7. Continuum flux density: 7.1 Typical Value: 0.5-10 mJy 7.2 Continuum Peak Value: Unknown for this source 7.3 Required Continuum RMS: 0.03 mJy (to detect primary driving source of the flow as well as any lower-mass YSOs in the cluster) 7.4 Dynamic Range in Image: > 20 8. Line Intensity: 8.1 Typical value: > 10 Jy at 12CO line peak 10-100 mJy in high velocity wings 8.2 Required RMS per channel: 15 mJy/beam 8.3 Spectral Dynamic Range: > 10 9. Polarization: No 10. Time requested: 10.1 Integration time per field for the ALMA array (interferometric and total power observations): Assuming a multi-field mosaic, 30" primary beam, 15'x15' mosaic, 4 beams/arcmin => 60x60beams = 3600 fields (just less than Nyquist spaced). 15 mJy/beam RMS in each field => 1 min integration on each field (0.3 km/s resolution) x 3600 fields = 60 hrs. Because fields will overlap, we will gain roughly a root 2 increase in sensitivity over the mosaic region. Integration time = 60/sqrt(2) hrs = 45 hrs. Note on overhead: we will likely have to do several passes through the mosaic to collect the total 1 min integration required for each field. This will increase the overhead beyond what calibration and slew times require. The 12CO(2-1) line will have to be observed separately from 13CO and C18O, thus, 2 mosaics will have to be made, each requiring 45 hrs of total integration time. 10.2 The ACA will require 4 times more integration to achieve a similar RMS to the ALMA array (e.g. 180 hrs). 10.3 In summary, this project requires 90 hours of ALMA array time (interferometric and total power observations), and 180 hours of ACA time. However, see note below - we need a total power mosaic larger than the interferometer mosaic ==> either ACA or ALMA array time must increase. (Overhead is not included in this estimate.) Uncertainty: -------------------- How can this project obtain larger mosaics in Total Power than the field needed to be covered by the interferometer? Either one should use the entire array to map the largest size needed by the total power observations (this will increase total observing time by a factor of 2 or more) or it will need to use the ACA 12m dishes to get the total power observations and spend 4 times more time on a larger mosaic area (again, hogging ACA time). Will the ACA sensitivity in spectral line mode be adequate or does it require the full ALMA array? ********************************************************************** Review Munetake Momose (old version): Scientific scope is O.K., but the observing strategy and time estimate should be slightly modified because of the following two reasons: 1) According to the sensitivity calculator, the planned observation setup (f~230GHz, dV=0.6km/s, 1" beam and 1-minute integration per field) will result in ~13 mJy/beam rms for the line, which is roughly 2 times greater than the required rms level (6mJy/beam). This makes the required integration time longer by a factor of 4, or 240 seconds per field. 2) The author assumes that each line is observed separately. But the frequency of 13CO and C18O is so adjacent that these can be observed simultaneously, making the overall integration time shorter by a factor of 2/3. Therefore, if one adopt the same requirements for the rms level, velocity resolution and beam size as the original, the integration time should be 135 hrs x (8/3) = 360 hrs (180 hrs for 12CO and 180 hrs for 13CO & C18O). I think these requirements cannot be relaxed for a "deep" imaging of the outflows, though the mapping area could be somewhat compromised. Reply Shepherd: Perhaps there is some confusion on my part since I don't know how to access the ALMA sensitivity calculator (I just used Al Wootten's SPIE 2002 memo to get a rough estimate). In the proposal, dV=0.3, not 0.6 km/s (as stated above), and the required RMS = 15 mJy/beam, not 6 mJy/beam. However, the errors in dV and RMS would almost cancel in a sensitivity calculation, so perhaps the final estimate by Mosose San is OK. Please verify, is this correct? Does the sensitivity calculator give such different estimates from Al's memo? Assuming this, then the sensitivity calculator would say that 240s are required/field. You get a root(2) increase in sensitivity because of field overlap. With 3600 fields, the total integration time for the mosaic = 180 hours. In my proposal, I assumed 12CO (230 GHz), 13CO (220 GHz), and C18O (219 GHz) could be observed simultaneously. Although this is within the 16 GHz correlator bandwidth perhaps you can't observe lines just anywhere within that bandwidth??? If I assume all lines can be observed simultaneously, then I need 180 hours for ALMA, and 4 times this much time for the ACA/SD to get similar sensitivity or 720 hours. Comment Ewine: integration time needs to be sorted out. Reply Shepherd: Thanks for the link to the sensitivity calculator. It produces an answer very close to my earlier calculation so all is well there. Thus, at 220 GHz, 0.3 km/s, 1" res., 1m int, RMS = 18 mJy/beam at 230 GHz, RMS = 18.7 mJy/beam I requested 15 mJy/beam so this is not too different. Thus, my calculations were correct - it will take about 45 hrs to do the mosaic. You said in your last e-mail that doing 12co, 13co, & c18o together will mean that you may have to sacrifice one polarization (and thus loose in sensitivity). Not adequate. Thus, I will have to do 2 mosaics, one for 12co and one for 13co/c18o. The modified DRSP is below. Only sections 10.1 and 10.3 are changed. Comment Ewine: new DRSP is now baseline