# The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release

**Authors:** V. Smolcic, M. Novak, M. Bondi, P. Ciliegi, K. P. Mooley, E. Schinnerer, G. Zamorani, F. Navarrete, S. Bourke, A. Karim, E. Vardoulaki, S. Leslie, J. Delhaize, C. L. Carilli, S. T. Myers, N. Baran, I. Delvecchio, O. Miettinen, J. Banfield, M. Balokovic  
**arXiv:** [1703.09713](https://arxiv.org/abs/1703.09713)  
**Date:** 2017-03-28  
**Summary page:** https://www.summarizepaper.com/en/paper/1703.09713v1/

## Key points

- The VLA-COSMOS 3 GHz Large Project, led by V. Smolcic and a team of researchers, conducted 384 hours of observations using the Karl G. Jansky Very Large Array (VLA) at 3 GHz towards the two square degree Cosmic Evolution Survey (COSMOS) field.
- The final mosaic achieved an angular resolution of 0.75" with a median rms of 2.3 uJy/beam over the entire two square degrees.
- A multiscale, multifrequency synthesis algorithm was used to address variations in spectral shape and resolution across the broad 2 GHz band for imaging all data.
- The project resulted in a catalog containing 10,830 radio sources detected down to 5 sigma, with 67 sources identified as having multiple components.
- Astrometric accuracy within 0.01" was estimated for sources with a signal-to-noise ratio greater than 20 by comparing positions with data from the VLBA-COSMOS survey.
- An expected median radio spectral index of alpha=-0.7 was determined through survival analysis in conjunction with the VLA-COSMOS 1.4 GHz Joint Project catalog.
- Completeness corrections were computed using Monte Carlo simulations to derive corrected source counts at 3 GHz, aligning with previously derived counts based on single-pointing VLA data covering smaller areas.
- The project is noted as the largest and deepest radio continuum survey conducted at high angular resolution (0.75") to date, bridging the gap between last-generation surveys and paving the way for next-generation advancements in radio astronomy research into cosmic evolution and structure within our universe.

## Summary

The VLA-COSMOS 3 GHz Large Project, led by V. Smolcic and a team of researchers, successfully conducted 384 hours of observations using the Karl G. Jansky Very Large Array (VLA) at 3 GHz towards the two square degree Cosmic Evolution Survey (COSMOS) field. The final mosaic achieved an impressive angular resolution of 0.75" with a median rms of 2.3 uJy/beam over the entire two square degrees. To address variations in spectral shape and resolution across the broad 2 GHz band, a multiscale, multifrequency synthesis algorithm was utilized to image all data. The project resulted in a comprehensive catalog containing 10,830 radio sources detected down to 5 sigma, with 67 sources identified as having multiple components. By comparing the positions of these sources with data from the Very Long Baseline Array (VLBA)-COSMOS survey, the team estimated an astrometric accuracy within 0.01" for sources with a signal-to-noise ratio greater than 20. Through survival analysis in conjunction with the VLA-COSMOS 1.4 GHz Joint Project catalog, an expected median radio spectral index of alpha=-0.7 was determined. Completeness corrections were computed using Monte Carlo simulations to derive corrected source counts at 3 GHz, which aligned with previously derived counts based on single-pointing VLA data covering smaller areas. In summary, the VLA-COSMOS 3 GHz Large Project stands out as the largest and deepest radio continuum survey conducted at high angular resolution (0.75") to date. This groundbreaking endeavor effectively bridges the gap between last-generation surveys and sets the stage for next-generation advancements in radio astronomy research and exploration into cosmic evolution and structure within our universe.