pycprops

Python implementation of the CPROPS algorithm from Rosolowsky & Leroy (2006).

This implements the same approaches developed in that paper, but there are a few changes in the shift to python:

• Local maximum identification and decimation uses the astrodendro dendrogram generation package, which is much faster than the approach used in the original IDL version.
• The assignment of pixels to clouds uses the scikit-image segmentation toolkit, which leads to different (better) pixel assignment around a local maxium. The boundaries between clouds are more "natural" than they were in the original cprops code.
• Property extrapolation uses actual robust regression leading to <10% differences in some properties.

Installation

pycprops is an installable python package. Clone or download the github repository.

git clone https://github.com/PhangsTeam/pycprops.git
cd pycprops
python setup.py install

After installation, you can run in python:

import pycprops
import astropy.units as u
cubefile = 'mycube.fits'  # Your cube
mask = 'mycube.mask.fits' # Mask defining where to find emission
d = 8.0 * u.kpc           # Distance (with units)

pycprops.fits2props(cubefile,
                    mask_file=mask,
                    distance=d,               
                    asgnname='mycube.asgn.fits',
                    propsname='mycube.props.fits')

The results of the pycprops code is an assignment file (mycube.asgn.fits) and a FITS BINTABLE (mycube.props.fits) catalog of GMC properties. The tags in that catalog are described in the table below.

Tag Name	Description
NPIX	The total number of pixels in the cloud.
CLOUDNUM	The cloud number from this data file.
XCTR_PIX	The x position of the center of the cloud in pixels.
XCTR_DEG	The x position of the center of the cloud in decimal degrees.
YCTR_PIX	The y position of the center of the cloud in pixels.
YCTR_DEG	The y position of the center of the cloud in decimal degrees.
VCTR_PIX	The v position of the center of the cloud in pixels.
VCTR_KMS	The v position of the center of the cloud in km/s.
POSANG	The position angle of the cloud (measured from the X-axis)
MOMXPIX	The 2nd moment of the emission the x-direction in pixels.
MOMXPIX_UC	The fractional uncertainty of the 2nd moment in the x-direction.
MOMXPIX_NOEX	The 2nd moment of the emission the x-direction in pixels with no extrapolation
MOMXPIX_NOEX_UC	The fractional uncertainty of the 2nd moment in the x-direction with no extrapolation.
MOMYPIX	The 2nd moment of the emission the y-direction in pixels.
MOMYPIX_UC	The fractional uncertainty of the 2nd moment in the y-direction.
MOMYPIX_NOEX	The 2nd moment of the emission the y-direction in pixels with no extrapolation.
MOMYPIX_NOEX_UC	The fractional uncertainty of the 2nd moment in the y-direction with no extrapolation.
MOMMAJPIX	The 2nd moment of the emission along the major axis in pixels.
MOMMAJPIX_UC	The fractional uncertainty of the 2nd moment in along the major axis.
MOMMAJPIX_NOEX	The 2nd moment of the emission along the major axis in pixels with no extrapolation.
MOMMAJPIX_NOEX_UC	The fractional uncertainty of the 2nd moment along the major axis with no extrapolation.
MOMMINPIX	The 2nd moment of the emission along the minor axis in pixels.
MOMMINPIX_UC	The fractional uncertainty of the 2nd moment in along the minor axis.
MOMMINPIX_NOEX	The 2nd moment of the emission along the minor axis in pixels with no extrapolation.
MOMMINPIX_NOEX_UC	The fractional uncertainty of the 2nd moment along the minor axis with no extrapolation.
MOMVPIX	The 2nd moment of the emission the v-direction in pixels.
MOMVPIX_UC	The fractional uncertainty of the 2nd moment in the v-direction.
MOMVPIX_NOEX	The 2nd moment of the emission the v-direction in pixels with no extrapolation.
MOMVPIX_NOEX_UC	The fractional uncertainty of the 2nd moment in the v-direction with no extrapolation.
RAD_PC	The cloud radius in parsecs.
RAD_UC	The fractional uncertainty in the cloud radius.
RAD_NODC	The cloud radius without deconvolution in parsecs.
RAD_NODC_UC	The fraction uncertainty in the cloud radius without deconvolution.
RAD_NOEX	The radius without extrapolation in parsecs.
RAD_NOEX_UC	The fractional uncertainty in the radius without extrapolation.
RAD_NODC_NOEX	The radius without deconvolution or extrapolation in parsecs.
RAD_NODC_NOEX_UC	The fraction uncertainty in the radius without deconvolution or extrapolation.
SIGV_KMS	The velocity dispersion in km/s.
SIGV_UC	The fractional uncertainty in the velocity dispersion.
SIGV_NODC	The velocity dispersion without deconvolution in km/s.
SIGV_NODC_UC	The fraction uncertainty in the velocity dispersion without deconvolution.
SIGV_NOEX	The velocity dispersion without extrapolation in km/s.
SIGV_NOEX_UC	The fraction uncertainty in the velocity dispersion without extrapolation.
SIGV_NODC_NOEX	The velocity dispersion without deconvolution or extrapolation in km/s.
SIGV_NODC_NOEX_UC	The fraction uncertainty in the velocity dispersion without extrapolation or deconvolution.
FLUX_KKMS_PC2	The luminosity of the cloud in K km/s pc2.
FLUX_UC	The fractional uncertainty of the luminosity.
FLUX_NOEX	The luminosity of the cloud in K km/s pc2 without extrapolation.
FLUX_NOEX_UC	The fractional uncertainty of the luminosity without extrapolation.
MLUM_MSUN	The luminous (CO) mass of the cloud in M .
MLUM_UC	The fractional uncertainty in the luminous mass.
MVIR_MSUN	The virial mass of the cloud in M .
MVIR_UC	The fractional uncertainty in the virial mass.
NAME	The file name that was used to generate the properties.
BEAMFWHM_PC	The FWHM of the beam projected into parsecs.
SIGCHAN_KMS	The equivalent velocity dispersion of a channel in km/s
GALNAME	The name of the galaxy that hosts the molecular cloud (can be defined later).
RMSTORAD	The scaling factor used between 2nd moment in the position and the radius.
PPBEAM	The number of pixels per beam (area).
S2N	The peak signal-to-noise ratio in the cloud.
TMAX_K	The peak antenna temperature in Kelvins.
DISTANCE_PC	The distance to the cloud in parsecs.