Overview

Pröst is a code for host-galaxy identification of extragalactic transients. It’s fast, probabilistic, and highly customizable.

Pröst was developed to improve the quality of associations using prior information about the survey being conducted and the nature of the transients targeted. The user defines priors on the redshift and absolute magnitude of an expected host, and on the fractional offset (angular separation scaled by galaxy radius) between a discovered transient and its host. Likelihoods are also defined for these properties. Each candidate is assigned a posterior probability of hosting the transient in question, and the source with the highest probability is chosen as host.

Each association is made multiple times while propagating uncertainties in each candidate’s photometric and morphological properties, thereby providing uncertainty estimates on each final association. The probability that the true host was missed is also provided.

Multiple catalogs are currently supported:

• GLADE+ v1

• The Dark Energy Camera Legacy Survey (DECaLS) Data Release 9

• Pan-STARRS Data Release 2

Associations with Pröst can be made in serial or parallelized across multiple cores, making it scalable for the next generation of synoptic surveys.

Installation

Installation can be done via pip (ideally in a conda environment):

>> conda create env -n <env_name> python=3.10
>> conda activate <env_name>
>> pip install astro-prost

Once installed, head over to the Notebooks tab for a tutorial on how to use the code.