The CO Line Atlas within the Whirlpool galaxy survey (CLAWS)

CLAWS is an IRAM-30 m large program, wide-area, multi-line mapping survey targeting a multitude of CO isotopologue lines in the 1 mm and 3 mm windows across the full disk of the nearby spiral galaxy M51 (resolution 15-30" at 230 GHz and 110 GHz translating to 0.5-1.5 kpc). CLAWS PIs are Kazimierz Sliwa and Toshiki Saito. Analysis of the survey data is being led by Jakob den Brok and Frank Bigiel at the University of Bonn.
The survey covers the key CO isotopologue rotational lines C18O(1-0), 13CO(1-0), and C17O(1-0) at 3 mm and C18O(2-1), 13CO(2-1), and 12CO(2-1) at 1mm. It is complemented by line images from the IRAM 30-m large program PAWS (12CO(1-0), PI: Eva Schinnerer; Pety et al. 2013), as well as dense gas tracers from the IRAM 30-m large program EMPIRE (HCN, HCO+, and HNC J=1-0, PI: Frank Bigiel; Jimenez-Donaire et al. 2019). The core goals of CLAWS are to constrain CO excitation and chemistry across M51 and to constrain the local physical conditions of the gas using the wealth of information on CO isotopologue line emission.
We have processed the data following the methodology adopted for the IRAM Large Programs EMPIRE and HERACLES (PI: Adam Leroy, Fabian Walter; Leroy et al. 2009). Details will be presented in den Brok et al., in prep. The IRAM repository provides the following data products: data cubes, noise-per-channel maps, and integrated intensity (moment-0) maps for all lines, plus intensity-weighted velocity (moment-1) maps, line width (FWHM, moment-2) maps, equivalent width maps, and peak temperature maps for 12CO(2-1) and 13CO(1-0) only. For each moment map, we provide the corresponding uncertainty map as well. All line moments are calculated within a mask generated from the high S/N CO(2-1) data. We provide all maps at native and at a common resolution of 33". The associated README file provides a detailed description of the data release.
Tabulated, resolved ("pixel-by-pixel") line measurements for the sample will be provided in the upcoming survey paper (den Brok et al, in prep). Please do not hesitate to contact Frank Bigiel and Jakob den Brok (, for further questions or to inform them about the use of the data for further scientific analysis or publications.
The following acknowledgment would be appreciated: "This work made use of data from CLAWS, 'The IRAM 30-m CO M51 Large Program' (den Brok et al., in prep.)." Acknowledgment of the CLAWS survey is also appreciated if data are used in public presentations.

The data repository is at IRAM.

- Jiménez-Donaire M. J., et al., 2019, ApJ, 880, 127
- Leroy A. K., et al., 2009, AJ, 137, 4670
- Pety J., et al., 2013, ApJ, 779, 43