Title  Study of Gas Masses and Star Formation Efficiencies in Nearby Galaxies 
Pi     J. Turner
Time   120 hrs
1. Study of Gas Masses and Star Formation Efficiencies in Nearby Galaxies
J. Turner et al.

2. We will map CO (2-1) emission at 1.5" resolution in a
representative sample of nearby gas-rich (spiral and irregular)
star-forming galaxies. The goal is to do a detailed study of gas and
its relation to star formation. With CO gas masses, we can determine
star formation efficiencies on sizescales of 30-60 pc, using
ground-based Halpha images, radio continuum, and SIRTF photometry. We
choose CO (2-1) instead of the (1-0) transition to obtain simultaneous
1mm continuum measurements, which provides another constraint on gas
mass. We have chosen a representative range of Hubble types, galaxies
with and without starbursts; most of the galaxies have SIRTF GTO
programs for fIR photometry. We will map a 10'x10' region in each of
the galaxies; this will cover most of the galaxy at 20-50 pc
resolution.

3. Number of sources: 4

4. Coordinates:

	4.1 NGC1097 (interacting and strongly barred galaxy; 8'
                     diameter) 02h46m19.0s -30d16m30s
            M83     (starburst core, normal barred spiral; 12'
                    diameter) 13h37m00.9s -29d51m57s
            NGC5253 (dwarf E/S0 galaxy; efficient starburst;
                     5'x2') 13h39m55.9s -31d38m24s
	    NGC4945 (large spiral; 20'x4') 13h05m27.5s -49d28m06s
		
	4.2 Moving target: no
	4.3 Time critical: no
	
5. Spatial scales:
	5.1 Angular resolution: 1.5"
	5.2 Range of spatial scales/FOV:  ~10' fields: require 40^2=1600 point mosaics for each, OTF 
	mapping (some galaxies will have rectangular maps along their disks) Images contain 400x400 beams.
	5.3 Single dish: yes
	5.4 ACA: yes
	5.5 Subarrays: no
	
6. Frequencies:
	
	6.1	Receiver band: Band 6
	6.2	Continuum
	6.3	Spectral resolution 4 km/s
	6.4 	Spectral coverage 600 km/s
	
7. Continuum flux density

	7.1	Typical value 0
	7.2 	Continuum peak value: 50 mJy
	7.3 	Required continuum rms: 0.1 mJy/beam
	7.4 	Dynamic range in image:  500:1
	
8. Line Intensity 

	8.1 	Typical value: 0.5 K (up to 20K)
	8.2 	Required rms value per channel: 0.05 K 
	8.3	Spectral dynamic range: 400:1
	
	
9. Polarization  N/A

10. Integration time per setting: 1 minute per Nyquist setting, 1600
settings within a 10'x10'
	region, mosaic/OTF mode. Total integration time, without
calibration, 1600 minutes =
	27 hrs/galaxy. 4 galaxies x 30 hours = 120 hours about 5 days
w/o calibration, slew, rampup.

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Review Chris Carilli: OK, but possibly overestimates required time by
factor 2 since this is a mosaic.  The sensitivity they quote is per
1min pointing, but the pointings overlap. However, program is only 120
hrs total, so leave as-is.
--------------------------------------------------
Review v2.0:
 
Study of gas masses and star-formation efficiencies...
Turner et al. 

Again `SIRTF' updates desirable. In light of SINGS being more and more
complete, should this modify the target choice? Is there again any
chance for synergistic interpretation and target matching with other
Turner et al. continuum/line surveys? Here mosaicking suggests ACA is
essential component.