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The radio counterparts to the IRAS Redshift Survey galaxies are identified in the NRAO VLA Sky Survey (NVSS) catalog. Our new catalog of the infrared flux-limited (S 60µm ≥ 2 Jy) complete sample of 1809 galaxies lists accurate radio positions, redshifts, and 1.4 GHz radio and IRAS fluxes. This sample is six times larger in size and five times deeper in redshift coverage (to z ≈ 0.15) compared with those used in earlier studies of the radio and far-infrared (FIR) properties of galaxies in the local volume. The well known radio-FIR correlation is obeyed by the overwhelming majority (≥ 98%) of the infrared-selected galaxies, and the radio AGNs identified by their excess radio emission constitute only about 1% of the sample, independent of the IR luminosity. These FIR-selected galaxies can account for the entire population of late-type field galaxies in the local volume, and their radio continuum may be used directly to infer the extinction-free star formation rate in most cases. Both the 1.4 GHz radio and 60 µm infrared luminosity functions are reasonably well described by linear sums of two Schechter functions, one representing normal, late-type field galaxies and the second representing starbursts and other luminous infrared galaxies. The integrated FIR luminosity density for the local volume is (4.8 ± 0.5) × 10 7 L ⊙ Mpc −3 , less than 10% of which is contributed by the luminous infrared galaxies with L F IR ≥ 10 11 L ⊙ . The inferred extinction-free star formation density for the local volume is 0.015 ± 0.005 M ⊙ yr −1 Mpc −3 .

Using free-free emission measured in the Ka-band (26 − 40 GHz) for 10 star-forming regions in the nearby galaxy NGC 6946, including its starbursting nucleus, we compare a number of star formation rate (SFR) diagnostics that are typically considered to be unaffected by interstellar extinction. These diagnostics include non-thermal radio (i.e., 1.4 GHz), total infrared (IR; 8 − 1000 µm), and warm dust (i.e., 24 µm) emission, along with hybrid indicators that attempt to account for obscured and unobscured emission from star-forming regions including Hα + 24 µm and UV + IR measurements.The assumption is made that the 33 GHz free-free emission provides the most accurate measure of the current SFR. Among the extranuclear star-forming regions, the 24 µm, Hα + 24 µm and UV + IR SFR calibrations are in good agreement with the 33 GHz free-free SFRs. However, each of the SFR calibrations relying on some form of dust emission overestimate the nuclear SFR by a factor of ∼2 relative to the 33 GHz free-free SFR. This is more likely the result of excess dust heating through an accumulation of non-ionizing stars associated with an extended episode of star formation in the nucleus rather than increased competition for ionizing photons by dust. SFR calibrations using the non-thermal radio continuum yield values which only agree with the 33 GHz free-free SFRs for the nucleus, and underestimate the SFRs from the extranuclear star-forming regions by an average factor of ∼2 and ∼4−5 before and after subtracting local background emission, respectively. This result likely arises from the CR electrons decaying within the starburst region with negligible escape, whereas the transient nature of star formation in the young extranuclear star-forming complexes allows for CR electrons to diffuse significantly further than dust heating photons, resulting in an underestimate of the true SFR. Finally, we find that the SFRs estimated using the total 33 GHz flux density appear to agree well with those from using the free-free emission due to the large thermal fractions present at these frequencies even when local diffuse backgrounds are not removed. Thus, rest-frame 33 GHz observations may act as a reliable method to measure the SFRs of galaxies at increasingly high redshift without the need of ancillary radio data to account for the non-thermal emission.

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Elliptical Gaussian fits are used in astronomy for accurate measurements of fundamental source parameters such as central position, peak flux density, and angular size. The full value of a noise-limited image can be realized only if the effects of noise on the fitted parameters are estimated accurately. This paper presents the equations of error propagation for two-dimensional elliptical Gaussian fits in the presence of Gaussian noise plus a new method that simplifies the use of a priori size constraints to reduce amplitude errors.For each of the n = 6 potentially free parameters p t (e.g, Pi=A, p 2 =x 0 , p 3 =yo, p 4 =a x , p 5 =

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