Thirty codes were added to the ASCL in February:

BALRoGO: Bayesian Astrometric Likelihood Recovery of Galactic Objects
binaryoffset: Detecting and correcting the binary offset effect in CCDs
CMasher: Scientific colormaps for making accessible, informative plots
DaMaSCUS-SUN: Dark Matter Simulation Code for Underground Scatterings – Sun Edition
EqTide: Equilibrium Tide calculations

extinction: Dust extinction laws
ForwardDiff: Forward mode automatic differentiation for Julia
GalRotpy: Parametrize the rotation curve and gravitational potential of disk-like galaxies
GLEAM: Galaxy Line Emission and Absorption Modeling
hardCORE: Exoplanet core radius fractions calculator

HUAYNO: Hierarchically split-Up AstrophYsical N-body sOlver N-body code
lensingGW: Lensing of gravitational waves
Lightbeam: Simulate light through weakly-guiding waveguides
mirkwood: SED modeling using machine learning
MOSAIC: Multipole operator generator for Fast Multipole Method operators

MST: Minimum Spanning Tree algorithm for identifying large-scale filaments
Multi_CLASS: Cross-tracer angular power spectra of number counts using CLASS
MUSE-PSFR: PSF reconstruction for MUSE WFM-AO mode
nway: Bayesian cross-matching of astronomical catalogs
OPUS: Interoperable access to analysis and simulation codes

Piff: PSFs In the Full FOV
Pixell: Rectangular pixel map manipulation and harmonic analysis library
polgraw-allsky: All-sky almost-monochromatic gravitational-wave pipeline
PyAutoFit: Classy probabilistic programming
PyFstat: Continuous gravitational-wave data analysis

RASSINE: Normalizing 1D stellar spectra
spinOS: SPectroscopic and INterferometric Orbital Solution finder
ThumbStack: Map and profile stacking pipeline
viscm: Analyzing colormaps and creating new colormaps
X-PSI: X-ray Pulse Simulation and Inference

Eighteen codes were added to the ASCL in January:

3LPT-init: Initial conditions with third-order Lagrangian perturbation for cosmological N-body simulations
apogee: Tools for APOGEE data
Avocado: Photometric classification of astronomical transients and variables with biased spectroscopic samples
BAYES-LOSVD: Bayesian framework for non-parametric extraction of the LOSVD
cFS: core Flight System

Curvit: Create light curves from UVIT data
DarpanX: X-ray reflectivity of multilayer mirrors
Eigentools: Tools for studying linear eigenvalue problems
EphemMatch: Ephemeris matching of DR25 TCEs, KOIs, and EBs for false positive identification
Mask galaxy: Machine learning pipeline for morphological segmentation of galaxies

Nigraha: Find and evaluate planet candidates from TESS light curves
Octo-Tiger: HPX parallelized 3-D hydrodynamic code for stellar mergers
ptemcee: A parallel-tempered version of emcee
pyUPMASK: Unsupervised clustering method for stellar clusters
PyXspec: Python interface to XSPEC spectral-fitting program

radiowinds: Radio Emission from Stellar Winds
stratsi: Stratified streaming instability
whereistheplanet: Predicting positions of directly imaged companions

Twenty-six codes were added to the ASCL in December:

BinaryStarSolver: Orbital elements of binary stars solver
BlackHawk: Black hole evaporation calculator
dolphin: Automated pipeline for lens modeling
DRAGraces: Reduction pipeline for GRACES spectra

EinsteinPy: General Relativity and gravitational physics problems solver
EOS: Equation of State for planetary impacts
getsf: Multi-scale, multi-wavelength sources and filaments extraction
HCGrid: Mapping non-uniform radio astronomy data onto a uniformly distributed grid

HydroCode1D: 1D finite volume code
LALSuite: LIGO Scientific Collaboration Algorithm Library Suite
LIFELINE: LIne proFiles in massivE coLliding wInd biNariEs
MADLens: Differentiable lensing simulator

Magritte: 3D radiative transfer library
MLC_ELGs: Machine Learning Classifiers for intermediate redshift Emission Line Galaxies
NSCG: NOIRLab Source Catalog Generator
Pomegranate: Probabilistic model builder

PyXel: Astronomical X-ray imaging data modeling
Robovetter: Automatic vetting of Threshold Crossing Events (TCEs)
seaborn: Statistical data visualization
sedop: Optimize discrete versions of common SEDs

Sengi: Interactive viewer for spectral outputs from stellar population synthesis models
SimCADO: Observations simulator for infrared telescopes and instruments
Skye: Excess clustering of transit times detection
SLIT: Sparse Lens Inversion Technique

SWIGLAL: Access LALSuite libraries with Python and Octave scripts
TRAN_K2: Planetary transit search

Thirty codes were added to the ASCL in November 2020:

ACStools: Python tools for Hubble Space Telescope Advanced Camera for Surveys data
AdaMet: Adaptive Metropolis for Bayesian analysis
ARES: Accelerated Reionization Era Simulations
CAPTURE: Interferometric pipeline for image creation from GMRT data
Clustering: Code for clustering single pulse events

CWITools: Tools for Cosmic Web Imager data
DarkBit: Dark matter constraints calculator
DarkCapPy: Dark Matter Capture and Annihilation
DDCalc: Dark matter direct detection phenomenology package
DeepShadows: Finding low-surface-brightness galaxies in survey images

DYNAMITE: DYnamics, Age and Metallicity Indicators Tracing Evolution
EvapMass: Minimum mass of planets predictor
frbcat: Fast Radio Burst CATalog querying package
GoFish: Molecular line detections in protoplanetary disks
GOTHIC : Double nuclei galaxy detector

GPCAL: Instrumental polarization calibration in VLBI data
HaloGen: Modular halo model code
HSTCosmicrays: Analyzing cosmic rays in HST calibration data
Kalkayotl: Inferring distances to stellar clusters from Gaia parallaxes
kīauhōkū: Stellar model grid interpolation

MCMCDiagnostics: Markov Chain Monte Carlo convergence diagnostics
PNICER: Extinction estimater
REBOUNDx: Adding effects in REBOUND N-body integrations
reproject: Python-based astronomical image reprojection
RRATtrap: Rotating Radio Transient identifier

Scintools: Pulsar scintillation data tools
SEDkit: Spectral energy distribution construction and analysis tools
TLC: Tidally Locked Coordinates
tlpipe: Data processing pipeline for the Tianlai experiment
wobble: Time-series spectra analyzer

Fifteen codes were added to the ASCL in October 2020:

Astronomaly: Flexible framework for anomaly detection in astronomy
Exo-DMC: Exoplanet Detection Map Calculator
grapus: GRavitational instability PopUlation Synthesis
GSpec: Gamma-ray Burst Monitor analyzer
LaSSI: Large-Scale Structure Information

Legolas: Large Eigensystem Generator for One-dimensional pLASmas
lenspyx: Curved-sky python lensed CMB maps simulation package
MBF: MOLSCAT 2020, BOUND, and FIELD for atomic and molecular collisions
Pix2Prof: Deep learning for textraction of useful sequential information from galaxy imagery
plancklens: Planck 2018 lensing pipeline

relxill: Reflection models of black hole accretion disks
ROGER: Automatic classification of galaxies using phase-space information
stella: Stellar flares identifier
stsynphot: synphot for HST and JWST
TACHE: TensoriAl Classification of Hydrodynamic Elements

Twenty-five codes were added to the ASCL in September 2020:

AstroVaDEr: Unsupervised clustering and synthetic image generation
Binary-Speckle: Binary or triple star parameters
CASI-3D: Convolutional Approach to Structure Identification-3D
Chrono: Multi-physics simulation engine
cosmoFns: Functions for observational cosmology

CosmoloPy: Cosmology package for Python
CRAC: Cosmology R Analysis Code
DASTCOM5: JPL small-body data browser
FLEET: Finding Luminous and Exotic Extragalactic Transients
halomod: Flexible interface for the halo model of dark matter halos

Harmonia: Hybrid-basis inference for large-scale galaxy clustering
ISPy3: Integrated-light Spectroscopy for Python3
J plots: Tool for characterizing 2D and 3D structures in the interstellar medium
JetSeT: Numerical modeling and SED fitting tool for relativistic jets
MADHAT: Gamma-ray emission analyzer

minot: Modeling framework for diffuse components in galaxy clusters
MLG: Microlensing with Gaia
MSL: Mining for Substructure Lenses
oxkat: Semi-automated imaging of MeerKAT observations
Paramo: PArticle and RAdiation MOnitor

pySpectrum: Power spectrum and bispectrum calculator
PyWST: WST and RWST for astrophysics
rcosmo: Cosmic Microwave Background data analysis
SPInS: Stellar Parameters INferred Systematically
vlt-sphere: Automatic VLT/SPHERE data reduction and analysis

Twenty-seven codes were added to the ASCL in August 2020:

Barry: Modular BAO fitting code
CMEchaser: Coronal Mass Ejection line-of-sight occultation detector
CVXOPT: Convex Optimization
DUCC: Distinctly Useful Code Collection

Eclaire: CUDA-based Library for Astronomical Image REduction
healpy: Python wrapper for HEALPix
HorizonGRound: Relativistic effects in ultra-large-scale clustering
iFIT: 1D surface photometry code

kinesis: Kinematic modeling of clusters
KLLR: Kernel Localized Linear Regression
Magnetizer: Computing magnetic fields of evolving galaxies
maxsmooth: Derivative constrained function fitting

MUSIC2-monofonIC: 3LPT initial condition generator
ParaMonte: Plain powerful parallel Monte Carlo library
PhaseTracer: Cosmological phases mapping
PySAP: Python Sparse data Analysis Package

ramses2hsim: RAMSES output to 3D data cube for HSIM
SEDBYS: Spectral Energy Distribution Builder for Young Stars
SOT: Spin-Orbit Tomography
sslf: A simple spectral-line finder

SuperNNova: Photometric classification
SuperRAENN: Supernova photometric classification pipeline
TDEmass: Tidal Disruption Event interpretor
TRISTAN: TRIdimensional STANford code

Ujti: Geodesics in general relativity
Umbrella: Asteroid detection, validation, and identification
zeus: Lightning Fast MCMC

Twenty-four codes were added to the ASCL in July 2020:

CaTffs: Calcium triplet indexes
CosmoGRaPH: Cosmological General Relativity and (Perfect fluid | Particle) Hydrodynamics
DarkHistory: Modified cosmic ionization and thermal histories calculator
FleCSPH: Parallel and distributed SPH implementation based on the FleCSI
GProtation: Measuring stellar rotation periods with Gaussian processes

hierArc: Hierarchical analysis of strong gravitational lenses
JB2008: Empirical Thermospheric Density Model
Line-Stacker: Spectral lines stacking
MAGI: Initial-condition generator for galactic N-body simulations
MPSolve: Multiprecision Polynomial SOLVEr

OSPEX: Object Spectral Executive
PARS: Paint the Atmospheres of Rotating Stars
PeTar: ParticlE Tree & particle-particle & Algorithmic Regularization code for simulating massive star clusters
polyMV: Multipolar coefficients converter
PoPE: Population Profile Estimator

PSRVoid: Statistical suite for folded pulsar data
pygwinc: Gravitational Wave Interferometer Noise Calculator
ReadPDS: Visualization tools for PDS4 data
SPARTA: SPectroscopic vARiabiliTy Analysis
SPARTA: Subhalo and PARticle Trajectory Analysis

spex_to_xspec: Convert SPEX output to XSPEC input
SPEX: Spectral Executive
TROVE: Theoretical ROVibrational Energies
wdtools: Spectroscopic analysis of white dwarfs

Twenty-three codes were added to the ASCL in June 2020:

2D-FFTLog: Generalized FFTLog algorithm for non-Gaussian covariance matrices
ARCHI: Add-on pipeline module for background star analysis from CHEOPS data
AstroCatR: Time series reconstruction of large-scale astronomical catalogs
AxionNS: Ray-tracing in neutron stars

CARACal: Containerized Automated Radio Astronomy Calibration pipeline
CosmoCov: Configuration space covariances for projected galaxy 2-point statistics
CosmoLike: Cosmological Likelihood analyses
deepSIP: deep learning of Supernova Ia Parameters

DeepSphere: Graph-based spherical convolutional neural network for cosmology
FAMED: Extraction and mode identification of oscillation frequencies for solar-like pulsators
GenetIC: Initial conditions generator for cosmological simulations
HEARSAY: Simulations for the probability of alien contact

JoXSZ: Joint X-ray and SZ fitting for galaxy clusters in Python
KinMS: Three-dimensional kinematic modelling of arbitrary gas distributions
MCSED: Spectral energy distribution fitting package for galactic systems
Powderday: Dust radiative transfer package

PRIISM: Python module for Radio Interferometry Imaging with Sparse Modeling
PRISim: Precision Radio Interferometer Simulator
pxf_kin_err: Radial velocity and velocity dispersion uncertainties estimator
PyPopStar: Single-age, single-metallicity populations generator

SERVAL: SpEctrum Radial Velocity AnaLyser
TATOO : Tidal-chronology Age TOOl
TATTER: Two-sAmple TesT EstimatoR

Sixteen codes were added to the ASCL in April 2020:

ArviZ: Exploratory analysis of Bayesian models
ASTRAEUS: Semi-analytical semi-numerical galaxy evolution and reionization code
Finesse: Frequency domain INterfErometer Simulation SoftwarE
FUNDPAR: Deriving FUNDamental PARameters from equivalent widths

IllinoisGRMHD: GRMHD code for dynamical spacetimes
IRDAP: SPHERE-IRDIS polarimetric data reduction pipeline
kombine: Kernel-density-based parallel ensemble sampler
Locus: Optimized differential photometry

PPMAP: Column density mapping with extra dimensions
PRECISION: Astronomical infrared observations data reduction
PyCosmo: Multi-purpose cosmology calculation tool
PyKat: Python interface and tools for Finesse

PyWD2015: Wilson-Devinney code GUI
stardate: Measure precise stellar ages
Tangra: Software for video photometry and astrometry
WD: Wilson-Devinney binary star modeling

And twenty codes were added in May 2020:

2DBAT: 2D Bayesian Automated Tilted-ring fitter
AMPEL: Alert Management, Photometry, and Evaluation of Light curves
Carpyncho: VVV Catalog browser toolkit
cdetools: Tools for Conditional Density Estimates

FETCH: Fast Extragalactic Transient Candidate Hunter
FFANCY: Fast Folding Algorithm for pulsar searching
gotetra: Cosmic velocity fields tracking through the use of tetrahedra
HiFLEx: Echelle data reduction pipeline

HIPSTER: HIgh-k Power Spectrum EstimatoR
MCRaT: Monte Carlo Radiation Transfer
michi2: SED and SLED fitting tool
NNKCDE: Nearest Neighbor Kernel Conditional Density Estimation

qubefit: MCMC kinematic modeling
RAPP: Robust Automated Photometry Pipeline
REDFIT: Red-noise spectra directly from unevenly spaced time series
RFCDE: Random Forests for Conditional Density Estimation

RID: Relativistic Image Doubling in water Cherenkov detectors
RM-Tools: Rotation measure (RM) synthesis and Stokes QU-fitting
RoLo: Calculate radius and potential of the Roche Lobe
s3PCF: Compute the 3-point correlation function in the squeezed limit