cmc-browser

This small library has two main purposes, managing a local grid of CMC models and handling the loading of CMC snapshots.

On the managing side of things, this library will index all models and snapshots in a given directory and also allows for the automated downloading of new CMC models from the web server.

Here's an example of a simple workflow, indexing some local models, listing the snapshots of a model and downloading a new model:

from cmcbrowser import CMCBrowser

# initialize cmcbrowser in a specific directory
b = CMCBrowser(ss_dir="/home/peter/research/CMC-grid/grid/")


b.list_models()

Found the following models:
N4e5_rv1_rg20_Z0.0002
N4e5_rv1_rg8_Z0.02
N1.6e6_rv0.5_rg8_Z0.002
N2e5_rv0.5_rg2_Z0.02
N1.6e6_rv2_rg20_Z0.02
N1.6e6_rv0.5_rg20_Z0.002
N1.6e6_rv1_rg2_Z0.0002
N4e5_rv1_rg8_Z0.0002
N2e5_rv0.5_rg20_Z0.02
N4e5_rv1_rg8_Z0.002
N4e5_rv2_rg20_Z0.02
N1.6e6_rv2_rg20_Z0.002

b.list_snapshots(model_name="N2e5_rv0.5_rg2_Z0.02")

Found the following snapshots:
Regular Snapshots:
initial.snap0489.dat.gz
initial.snap0036.dat.gz
initial.snap0000.dat.gz

On the loading side of things, this library augments the Snapshot loading functionality provided by cmctoolkit.

Most of this functionality is convenience, like parsing the metallicity from the model name or collecting useful quantities like the initial cluster mass, half-mass radius, escape velocity and core radius. It also allows for easy loading of snapshots in either the old tar.gz format or the new HDF5 format.

# load in a snapshot, place it at 5 kpc
b.load_snapshot(
    model_name="N2e5_rv0.5_rg20_Z0.02",
    h5_key="3(t=9.5000169Gyr)",
    distance=5.0,
    mode="h5",
)

This returns a regular cmctoolkit Snapshot object, just with some of that extra info attached which means that we can directly use the methods implemented in cmctoolkit like adding photometry or make a 2D projection:

# select a loaded snapshot
snap = b.loaded_snapshots["N2e5_rv0.5_rg20_Z0.02/3(t=9.5000169Gyr)"]

# load in the list of filters we want to calculate photometry for
filttable = ck.load_filtertable("/home/peter/research/cmctoolkit/filt_index.txt")

# add photometry
snap.add_photometry(filttable)

# add in projected 2d postions and velocities
snap.make_2d_projection()

Finally, downloading new models:

b.download_new_model(N="4e5", rv="1", rg="20", Z="0.0002")

Which will construct the appropriate URL, send the request to the CMC web server, download the model, unpack it, add it to the existing grid, index the snapshots and clean up any leftover files.

See also

cmc-obs: Another small library which takes in a Snapshot object from cmc-browser and extracts a series of mock observations, designed to be as realistic as possible.