This project presents a comprehensive spectroscopic analysis of O and B-type stars, neutron stars, and white dwarfs, with a focus on the detection of helium (He) and oxygen (O) in stellar atmospheres. By leveraging data from the Sloan Digital Sky Survey (SDSS) and utilizing tools such as Astropy, Astroquery, and Specutils, the project aims to identify key spectral lines of helium and oxygen, as well as the formation of heliox (OHe) molecules. The methodology involves querying SDSS for relevant spectral data, filtering and analyzing it based on stellar classification, and visualizing the results using advanced techniques. The findings contribute to the understanding of stellar evolution, chemical processes, and the role of these elements in various stellar classes. Additionally, the project incorporates interactive data exploration with Aladin Lite and Simbad, offering a robust framework for future astrophysical research.

This notebook provides a comprehensive approach for analyzing and visualizing astronomical data from FITS (Flexible Image Transport System) files, focusing on moment maps derived from molecular line emissions within the galaxy NGC 0628. The analysis involves applying various image processing techniques to handle corrupted pixels, reconstruct images, and enhance the quality of moment maps. The notebook also demonstrates how to simulate super-resolution to improve the spatial resolution of the data. By utilizing Gaussian filtering, median filtering, and contrast enhancement, the approach improves the clarity and precision of the data, making it suitable for detailed astrophysical studies. This tool serves as an efficient method for processing and visualizing large-scale astronomical datasets for further analysis and scientific interpretation.

NEMESISPY infers the atmospheric properties of exoplanets, such as chemical composition, using spectroscopic data. The package calculates radiative transfer using the correlated-k approximation and for parametric atmospheric modelling. NEMESISPY is a Python implementation of the well-established Fortran NEMESIS library (ascl:2210.009), which has been applied to the atmospheric retrievals of both solar system planets and exoplanets employing numerous different observing geometries.

IcyDwarf calculates the coupled physical-chemical evolution of an icy dwarf planet or moon. The code calculates the thermal evolution of an icy planetary body (moon or dwarf planet), with no chemistry, but with rock hydration, dehydration, hydrothermal circulation, core cracking, tidal heating, and porosity; the depth of cracking and a bulk water:rock ratio by mass in the rocky core are also computed. It also calculates whether cryovolcanism is possible by the exsolution of volatiles from cryolavas. IcyDwarf also determines the equilibrium fluid and rock chemistries resulting from water-rock interaction in subsurface oceans in contact with a rocky core, up to 200ºC and 1000 bar.

SMINT (Structure Model INTerpolator) obtains posterior distributions on the H/He or H2O mass fraction of a planet; its interface is user-friendly. The parameters of the planet of interest are input with specifications on the priors that should be used. SMINT returns publication-ready plots presenting the joint parameters constraints obtained from interpolating the interior models grid of interest as well as confidence intervals for each parameter.

DarkMatters calculates multi-frequency and multi-messenger emissions from WIMP annihilation and decay. This can be done both for standard channels and custom models, with the ability to produce surface brightnesses and integrated fluxes as well as maps in FITS format to compare to actual data. DarkMatters uses an accelerated ADI solver such as GALPROP (ascl:1010.028) for electron diffusion with an innovative sparse matrix approach. Additionally, there is the option to use a Green's function approximate solution (implemented in both C++ and Python).

The numerical modeling code DustPOL-py calculates the multi-wavelength polarization degree of absorption and thermal dust emission based on Radiative Torque alignment (RAT-A), Magnetically enhanced RAT (MRAT) and Radiative Torque Disruption (RAT-D). The code saves the output files (wavelength and degree of polarization) for further analysis and is idealization for diffuse ISM, molecular clouds and star-forming regions; it also predicts the polarization spectrum for one- or two-dust layers. A web-interface GUI for DustPOL-py is also available.

DArk Matter SPIkes (DAMSPI) analyzes dark matter spikes around Intermediate Mass Black Holes (IMBHs) in the Milky Way. It extracts an IMBH catalog with the corresponding dark matter spike parameters from EAGLE simulations to probe a potential gamma-ray signal from dark matter self-annihilation. The catalog includes, among others, the coordinates, mass, formation redshift, and spike parameters for each individual IMBH.

jaxspec performs statistical inference on X-ray spectra. It loads an X-ray spectrum (in the OGIP standard), defines a spectral model from the implemented components, and calculates the best parameters using state-of-the-art Bayesian approaches. The code is built on top of JAX (ascl:2111.002) to provide just-in-time compilation and automatic differentiation of the spectral models, enabling the use of sampling algorithms. jaxspec is written in pure Python and is not dependent on HEASoft (ascl:1408.004).

mochi_class extends the hi_class code (ascl:1808.010), itself a patch to the Einstein-Boltzmann solver CLASS (ascl:1106.020). It replaces α-functions by stable basis to ensure stability and takes general functions of time as input, including the dark energy equation of state or its normalized background energy-density. mochi_class provides stability test checking for mathematical (classical) instabilities in the scalar field fluctuations, and also includes a GR approximation scheme, among other new capabilities.

HIILines analytically models lines emitted by the ionized interstellar medium (ISM). It covers [OIII], [OII], H_α, and H_β lines. The strength of HIILines is its high computational efficiency. It can be used for galaxy spectroscopic survey measurement interpolations assuming a one-zone picture and galaxy line emission measurement design and forecasts. HIILines also performs post-processing of hydrodynamical galaxy formation simulations for ISM emission lines.

McFine performs complex, multi-component hyperfine spectra fitting in astronomical data. It turns line intensities into gas conditions using a fully automated Bayesian method. Written in Python, the code uses Markov chain Monte Carlo (MCMC) to characterize model denegeracies. It handles local thermodynamic equilibrium (LTE) and radiative-transfer (RT) models and can fit individual spectra and data cubes; given a data cube, it can also use the neighboring information to attempt a better fit. McFine also fits the minimum number of distinct components to avoid overfitting.

The spectral classification code Diagnose assigns one of four classifications (star, galaxy, quasar, or unknown) to each source and returns a redshift estimate for the galaxies and quasars and a velocity estimate for the stars. The code uses a chi-squared minimization for linear combinations of principal component templates to determine a best-fit spectral classification and redshift estimate. It computes three best-fit chi-squared values: one for stellar type and velocity, one for galaxy type and redshift, and one for a quasar and redshift. Diagnose then compares the best fit of these three reduced chi-squared values to the second best fit and evaluates the difference against a statistical threshold.

The Unicorn pipeline produces data products from the 3D-HST grism survey of four CANDELS fields. It extracts interlaced 2D and 1D spectra for all objects in the Skelton et al. (2014) photometric catalogs. It then fits the 2D spectra and multi-band photometry to determine redshifts and emission line strengths. Unicorn is built on threedhst (ascl:2411.018) and has been superseded by grizli (ascl:1905.001).

threedhst reduces WFC3 grism exposures. It is essentially a wrapper around aXe (ascl:1109.016) and produces a catalog and other useful files; extracted 1D spectra are placed in a single file, and 2D spectra are in individual files. The code produces an HTML table with thumbnails of the direct images, 1D, and 2D spectra and supports the pipeline Unicorn (ascl:2411.019), which produces data products from the 3D-HST grism survey of four CANDELS fields. threedhst has been superceded by Grizli (ascl:1905.001).

CLASS LVDM modifies the CLASS code (ascl:1106.020) to incorporate the cosmological model of Lorentz invariance violation (LV) in gravity and dark matter. Compared to the usual CLASS code, it contains four new parameters: alpha, beta, and lambda characterize LV in the gravity sector
, and Y characterizes LV in the dark matter sector.

fits_warp smoothly removes the distorting effect of the ionosphere and restores sources to their reference positions in both the catalog and image domain. Image warping uses pixel offsets derived from a catalog of cross-matched sources. Though initially written for low-frequency radio astronomy, fits_warp can be used to de-distort any image distorted by some vector field which is sampled by some sparse pierce-points.

atlas-fit amends the results of spectroflat (ascl:2411.014) with calibration against a solar atlas. Data for wavelength calibration and continuum-correction is generated from flat field information and selected solar atlantes. The atlas-fit package provides two tools: one to generate a list of lines from the atlas and data to use for finding a wavelength solution (dispersion), and another to amend the calibration results from the spectroflat library.

Spectroflat flat fields spectro-polarimetric data. It can be plugged into existing Python-based data reduction pipelines or used as a standalone calibration and performance analysis tool. The code includes smile distortion correction and flat field extraction. The library expects the spatial domain on the vertical-axis and the spectral domain on the horizontal axis. Spectroflat does not include any file reading/writing routines and expects numpy arrays as input.

NE2001p is a fully Python implementation of the NE2001 Galactic electron density model. The code forward models the dispersion and scattering of compact radio sources, including pulsars, fast radio bursts, AGNs, and masers, and the model predicts the distances of radio sources that lack independent distance measures.

BSAVI (Bayesian Sample Visualizer) aids likelihood analysis of model parameters where samples from a distribution in the parameter space are used as inputs to calculate a given observable. For example, selecting a range of samples will allow you to easily see how the observables change as you traverse the sample distribution. At the core of BSAVI is the Observable object, which contains the data for a given observable and instructions for plotting it. It is modular, so you can write your own function that takes the parameter values as inputs, and BSAVI will use it to compute observables on the fly. It also accepts tabular data, so if you have pre-computed observables, simply import them alongside the dataset containing the sample distribution to start visualizing. Though BSAVI was developed for use in theoretical cosmology, it can be customized to fit a wide range of visualization needs.

MMLPhoto-z estimates the photo-z of quasars using a cross-modal contrastive learning approach. This method employs adversarial training and contrastive loss functions to promote the mutual conversion between multi-band photometric data features (magnitude, color) and photometric image features, while extracting modality-invariant features. MMLPhoto-z can also be applied to tasks like photo-z estimation for galaxies with missing magnitudes. Overall, this method proves effective in enhancing the photo-z estimation across diverse datasets and conditions.

ReverseDiff implements methods to take gradients, Jacobians, Hessians, and higher-order derivatives of native Julia functions (or any callable object) using reverse mode automatic differentiation (AD). While performance can vary depending on the functions you evaluate, the algorithms implemented by ReverseDiff generally outperform non-AD algorithms in both speed and accuracy.

Pycosmicstar studies the star formation history for different cosmological models. The package contains two abstract classes, cosmology and structureabstract. The class cosmology is passed as a parameter for the classes that implement structureabstract. This approach takes polymorphism into account. The modeling of structures and star formation are not strongly dependent on the cosmology. Pycosmicstar generates a new cosmological class that implements the methods of abstract class cosmology that is useful to study, for example, the role of dark energy in the cosmic star formation rate evolution.

Astrocats enables astronomers to construct their own curated catalogs of astronomical data with the intention of producing shareable catalogs of that data in human-readable formats. Astrocats is used by several existing open astronomy catalogs, including the Open Supernova Catalog, Open TDE Catalog, Open Nova Catalog, and the Open Black Hole Catalog.

EFTofPNG (Effective Field Theory of Post-Newtonian Gravity) performs high precision computations in the effective field theory of post-Newtonian (PN) Gravity, including spins. Written in Mathematica, it provides computer-algebra tools to derive analytical input for gravitational-wave source modelling relevant to current observatories. EFTofPNG has been used to derive of all currently known spin-dependent conservative interaction potentials in the post-Newtonian (PN) approximation to General Relativity (GR).

HBSGSep (Hierarchical Bayesian Star-Galaxy Separations) classifies stars and galaxies photometrically by fitting templates and hierarchically learning their prior weights. The hierarchical Bayesian algorithms are unsupervised and do not use a training set nor are priors set in advance of running the algorithms; the priors for the templates are inferred from the data themselves.

GAz calculates photometric redshifts for low redshift galaxies. It finds optimal polynomial forms to fit to data. It explores the very large space of high order polynomials while only requiring optimization of a small number of terms. Tested with the 2SLAQ LRG data set, GAz generalizes well to various data sets and redshift ranges.

DarkRayNet uses recurrent neural networks (RNNs) to quickly simulate antiprotons, antideuterons, protons and Helium cosmic ray (CR) spectra at Earth for an extensive range of parameters. The corresponding neural networks are trained on GALPROP (ascl:1010.028) simulations. DarkRayNet can also simulate the cosmic ray fluxes for antideuterons; the spectra can be predicted for a signal from dark matter annihilation DM Antideuterons and for secondary emission Secondary Antideuterons.

PyMerger detects binary black hole mergers from the Einstein Telescope based on a Deep Residual Neural Network (ResNet) model; the model was trained on combined data from all three proposed sub-detectors of ET (TSDCD). The model achieved high BBH detection rates. Though not trained on BNS and BHNS mergers, PyMerger successfully detected 11,477 BNS and 323 BHNS mergers in ET-MDC, indicating its potential for broader applicability.

flashcurve estimates the necessary time windows for adaptive binning light curves in Fermi-LAT data using raw photon data. Fluxes coming from Gamma rays measured by the Fermi-LAT satellite are extremely variable. Gamma-ray light curves produced by flashcurve, which uses deep learning, optimally use adaptive bin sizes to retrieve information about the source dynamics and to combine gamma-ray observations in a multi-messenger perspective.

Mosaic characterizes the beam shape and generate efficient tilings for efficient multi-beam observations. It consists of an interferometric pattern simulator and characterizer, an optimized tiling generator, and a beamforming weights calculator. It is being used in the filter-banking beamformer in the MeerKAT telescope; more than 200 pulsars have been discovered from the multiple beam observations supported by Mosaic.

**Finalflash** is a Python package designed for primary beam corrections of uGMRT radio interferometric images. The software uses frequency-dependent beam models and FITS file handling to improve the accuracy of radio astronomical data. It is open source and available under the MIT License. The code is hosted at https://github.com/arpan-52/Finalflash.

Extensible spacetime agnostic general relativistic ray-tracing (GRRT): Gradus.jl is a suite of tools related to tracing geodesics and calculating observational signatures of accreting compact objects. Gradus.jl requires only a specification of the non-zero metric components of a chosen spacetime in order to solve the geodesic equation and compute a wide variety of trajectories and orbits. Various algorithms for calculating physical quantities are implemented generically, so they may be used with different classes of spacetime with minimal effort.

Falcon-DM simulates intermediate mass ratio inspirals in DM spikes. This lightweight N-body code is written in C++ and is specifically tuned for simulating IMRIs embedded in dark matter (DM) spikes. It features a 2nd order Drift-Kick-Drift integrator using the symplectic HOLD scheme and symmetrized, individual, time-steps for accurate time-integration. Falcon-DM also offers post-Newtonian (PN) effects up to PN2.5 using the auxiliary velocity algorithm.

Heracles manages harmonic-space statistics on the sphere. It takes catalogs of positions and function values on the sphere and turns them into angular power spectra and mixing matrices. Heracles is both a Python library, to be used in notebooks or data processing pipelines, and a tool for running measurements from the command line using a configuration file.

fastPTA forecasts the sensitivity of future Pulsar Timing Array (PTA) configurations and assesses constraints on Stochastic Gravitational Wave Background (SGWB) parameters. The code can generate mock PTA catalogs with noise levels compatible with current and future PTA experiments. These catalogs can then be used to perform Fisher forecasts of MCMC simulations.

StellarSpectraObservationFitting (SSOF) measures radial velocities and creates data-driven models (with fast, physically-motivated Gaussian Process regularization) for the time-variable spectral features for both the telluric transmission and stellar spectrum measured by Extremely Precise Radial Velocity (EPRV) spectrographs (while accounting for the wavelength-dependent instrumental line-spread function). Written in Julia, SSOF provides two methods for estimating the uncertainties on the RVs and model scores based on the photon uncertainties in the original data. For quick estimates of the uncertainties, the code looks at the local curvature of the likelihood space; the second method for estimating errors is via bootstrap resampling.

Gaspery uses the Fisher Information Matrix (FIM) to evaluate different radial velocity (RV) observing strategies; this assists observational exoplanet astronomers in constructing the observing strategy that maximizes information (or minimizes uncertainty) on the RV semi-amplitude K. The code is flexible and generalizable, however, and can maximize information on any free parameter from any model, given a time series support (x-axis).

Kamodo provides access to, interpolation of, and visualization of space weather models and data. The code allows model developers to represent simulation results as mathematical functions which may be manipulated directly. As the software does not generate model outputs, users must acquire the desired model outputs before these outputs can be functionalized by the software. Kamodo handles unit conversion transparently and supports interactive science discovery through Jupyter notebooks with minimal coding.

CloudCovErr.jl debiases fluxes and improves error bar estimates for photometry on top of structured filamentary backgrounds. It first estimates the covariance matrix of the residuals from a previous photometric model and then computes corrections to the estimated flux and flux uncertainties. Using an infilling technique to estimate the background and its uncertainty dramatically improves flux and flux uncertainty estimates for stars in images of fields with significant nebulosity.

ARK implements Computational Fluid Dynamics applications, such as Euler and all-Mach regime, on a Cartesian grid with MPI+Kokkos. It provides a performance-portable Kokkos implementation for compressible hydrodynamics and performs simulations of convection without any approximation of Boussinesq nor anelastic type. It adapts an all-Mach number scheme into a well-balanced scheme for gravity, which preserves arbitrary discrete equilibrium states up to the machine precision. The low-Mach correction in the numerical flux allows ARK to be more precise in the low-Mach regime; the code is well suited for studying highly stratified and high-Mach convective flows.

The 1D radiative-equilibrium model Exo-REM simulates young gas giants far from their star and brown dwarfs. Fluxes are calculated using the two-stream approximation assuming hemispheric closure. The radiative-convective equilibrium is solved assuming that the net flux (radiative + convective) is conservative. The conservation of flux over the pressure grid is solved iteratively using a constrained linear inversion method. Rayleigh scattering from H2, He, and H2O, as well as absorption and scattering by clouds (calculated from extinction coefficient, single scattering albedo, and asymmetry factor interpolated from precomputed tables for a set of wavelengths and particle radii), are also taken into account.

DGEM compares different computation methods for three-dimensional dust continuum radiative transfer. This simple code is based on mcpolar, translated to C++, and refactored to realize and compare radiative transfer techniques, namely Monte Carlo, Quasi-Monte-Carlo, and the Directions Grid Enumeration Method (DGEM). DGEM uses precalculated directions of the photons propagation instead of the random ones to speed up the calculations process. The code also offers a gnuplot script for plotting the resulting images.

lensitbiases is an rFFT-based N1 lensing bias calculation and tests. It is tuned for TT, P-only or MV (GMV) like quadratic estimators. It performs rFFT-based N1 and N1 matrix calculations in ~ O(ms) time per lensing multipole for Planck-like config, which allows on-the-fly evaluation of the bias. It also calculates 5 rFFT's of moderate size per L for N1 TT, 20 for PP, and 45 for MV or GMV. lensitbiases is not particularly efficient for low lensing L's, since in this case one must use large boxes.

DIRTY (DustI Radiative Transfer, Yeah!) computes the radiative transfer and dust emission from arbitrary distributions of dust illuminated by arbitrary distributions of sources (usually stars). It uses Monte Carlo methods to solve the radiative transfer problem in full 3D including non-equilibrium and equilibrium thermal dust emission. As are other similar models, DUSTY is computationally intensive; as a result, it is written in C++.

solar-vSI performs Monte Carlo integration of multi-body phase space efficiently. The calculation of solar antineutrino spectra from 8B decay requires the integration of five-body phase space. Though there is no simple analytical approach to this problem, recursive relations can be used to facilitate numerical evaluations.

measure_extinction measures extinction due to dust absorbing photons or scattering photons out of the line-of-sight. Extinction applies to the case for a star seen behind a foreground screen of dust. This package provides the tools to measure dust extinction curves using observations of two effectively identical stars, differing only in that one is seen through more dust than the other.

Forcepho infers the fluxes and shapes of galaxies from astronomical images. It models the appearance of multiple sources in multiple bands simultaneously and compares to observed data via a likelihood function. Gradients of this likelihood allow for efficient maximization of the posterior probability or sampling of the posterior probability distribution via Hamiltonian Monte Carlo. The model intrinsic galaxy shapes and positions are shared across the different bands, but the fluxes are fit separately for each band. Forcepho does not perform detection; initial locations and (very rough) parameter estimates must be supplied by the user.

BayeSED implements full Bayesian interpretation of spectral energy distributions (SEDs) of galaxies and AGNs. It performs Bayesian parameter estimation using posteriori probability distributions (PDFs) and Bayesian SED model comparison using Bayesian evidence. Its latest version BayeSED3 supports various built-in SED models and can emulate other SED models using machine learning techniques.