1. Low Frequency Continuum Survey of Free-Free Emission in HII regions the LMC J. Turner 2. The goal is to measure and locate free-free emission from HII regions in star-forming regions of the Large Magellanic Cloud. The images will reveal at high spatial resolution the youngest massive star-forming regions that are optically obscured, and will be able to map regions containing the ionization equivalent of 1 O9 star. These observations will allow an important extension of our current knowledge of Galactic star formation to these nearby HII regions in a low metallicity setting. The submillimeter fluxes will be measured at 3 and 1mm, spectral regions which are relatively free of synchrotron and dust confusion, at resolutions comparable to the sizes of the HII regions themselves. These images will have the capability of imaging structure within HII complexes the size of Orion and of identifying compact HII regions by their size. Will be combined with EVLA images at lower frequency (K, Q.) 3. Number of sources: 4 4. Coordinates: 4.1 4 fields in LMC 5:23, -69 4.2 Moving target: no 4.3 Time critical: no 5. Spatial scales: 5.1 Angular resolution: 0.08" = .02 pc 5.2 Range of spatial scales/FOV: 3'x3' fields to cover 50 pc regions: require mosaics for each, using OTF if efficient for these fields. Details below. 5.3 Single dish: yes 5.4 ACA: yes 5.5 Subarrays: no 6. Frequencies: 6.1 Receiver band: Bands 3, and 6 6.2 Continuum 6.3 Spectral resolution N/A 6.4 Spectral coverage N/A 7. Continuum flux density 7.1 Typical value 0.2-0.4 mJy 7.2 Continuum peak value: 280 mJy/beam 7.3 Required continuum rms: ~0.05 mJy/beam to detect significant (>6 sigma) structure around an O9 star in an HII region the size of Orion Or .005 K 7.4 Dynamic range in image: 3000:1 (worst case) 8. Line Intensity N/A 9. Polarization N/A 10. Integration time per setting: 4 minutes at 3mm per sample point, which means 140 OTF maps at 108 seconds/map ==> 4.2 hours per source to achieve rms .02 mJy or .002K per sample point 2 minutes at 1mm per sample point, which means 150 OTF maps at 216 seconds/map ==> 9 hours per source to achieve rms = .07 mJy/bm, .002K per sample point 11. Total integration time for program: in round numbers 4 sources x 14 hrs/source = 56 hrs 12. Comments on observing strategy (e.g. line surveys, Target of Opportunity, Sun, ...): (optional) OTF mapping, 3'x3' fields 30"/second rate give 1 row in 6 seconds At 3mm must have 18 rows for oversampling at 10" row spacing to give 108 seconds per OTF map At 1mm must have 36 rows for oversampling at 5" row spacing to give 216 seconds per OTF map A 3'x3' map has 64 Nyquist samples at 3mm, so time per sample is 108/64 - 1.7 seconds per sample in each OTF map. To get required 4 minutes/sample requires 140 maps, or 140 maps*108seconds/map = 15,000 seconds = 4.2 hrs A 3'x3' map has 268 Nyquist samples at 1mm, so time per sample is 216/268 - 0.8 seconds per sample in each OTF map. To get required 2 minutes/sample requires 150 maps, or 150 maps*216seconds/map = 32,400 seconds = 9 hrs Zero and small spacing data requested since emission is expected on all scales and smoothing to see low level emission is desirable. **************************************************************** Review Christine Wilson: interesting program, looks OK to me What's missing: I'm surprised not to see more observations targeting the region around 30 Doradus, which is the most massive young star cluster in the Local Group. The proposals here include only free-free continuum and CO 2-1 observations. I'd think it would be interesting to look at the dust properties and several lines to try to trace density, temperature, surface density, etc. Response Jean Turner: program has been modified; 30 Dor has been moved to new DRSP 1.8.5. Comment Ewine: new DRSP is now baseline