Create Simulated Catalog

This module provides functionality to create a simulated catalog using data from the Roman Space Telescope. It leverages the LePhare photometric redshift estimation tool and other utilities to generate simulated data, process it, and save it in a structured format.

Module API

class roman_photoz.create_simulated_catalog.SimulatedCatalog(nobj: int = 1000, mag_noise: float = 0.1, seed=None)

Bases: object

A class to create a simulated catalog using the Roman telescope data.

data

A dictionary to store the data.

Type:: OrderedDict

lephare_config

Configuration for LePhare.

Type:: dict

flux_cols

List of flux column names.

Type:: list

flux_err_cols

List of flux error column names.

Type:: list

inform_stage

Placeholder for inform stage.

Type:: None

estimated

Holds all the results from roman_photoz.

Type:: None

filter_lib

Placeholder for filter library.

Type:: None

simulated_data_filename

Filename for the simulated data.

Type:: str

simulated_data

Placeholder for simulated data.

Type:: None

process(output_path: str = '', output_filename: str = 'roman_simulated_catalog.parquet', return_catalog: bool = False, refresh_lib_mag: bool = False)

Run the process to create the simulated catalog.

Parameters:

output_path (str, optional) – Path to save the output catalog (default: “”).
output_filename (str, optional) – Filename for the output catalog.
return_catalog (bool, optional) – If True, return the catalog in memory instead of saving to file. Default is False to maintain backward compatibility.

Returns:

The simulated catalog if return_catalog is True, otherwise None.

Return type:

Table or None

roman_photoz.create_simulated_catalog.main()

Command-Line Usage

Once roman-photoz is installed, you can create a simulated catalog using the CLI command roman-photoz-create-simulated-catalog. For example, to create a Roman multiband catalog with 1000 simulated objects and have it saved in the current directory under the name simulated_catalog.parquet, run the following command:

$ roman-photoz-create-simulated-catalog \
 --output-path ./ \
 --output-filename simulated_catalog.parquet \
 --nobj=1000

Usage Examples

Another way to create a simulated catalog is to use the SimulatedCatalog class directly in your Python code. For example:

from roman_photoz.create_simulated_catalog import SimulatedCatalog

# simulate 1000 objects and add a gaussian noise with sigma=0.15 mag
simulated_catalog1 = SimulatedCatalog(1000, mag_noise=0.15)

# simulate 5000 objects and add a gaussian noise with sigma=0.05 mag
simulated_catalog2 = SimulatedCatalog(5000, mag_noise=0.05)

# create the simulated catalogs and save them in the current directory
simulated_catalog1.process(output_filename="roman_simulated_catalog1.parquet")
simulated_catalog2.process(output_filename="roman_simulated_catalog2.parquet")