Basic Tools for Astrophysical Research
======================================

Data format used in astronomy
-----------------------------

-  `Flexible Image Transport System
   (FITS) <https://archive.stsci.edu/fits/>`__

   -  The default standard for the exchange of data in astronomy now
   -  The `full document of
      FITS <https://fits.gsfc.nasa.gov/users_guide/usersguide.pdf>`__
      and `the MAST data format
      guidelines <https://archive.stsci.edu/data_format.html>`__
   -  `CFITSIO <https://heasarc.gsfc.nasa.gov/fitsio/>`__ is a library
      of C and Fortran subroutines for reading and writing data files in
      FITS.
   -  `astropy.io.fits <https://docs.astropy.org/en/stable/io/fits/>`__
      can help you deal with FITS files in Python

-  `Advanced Scientific Data Format
   (ASDF) <https://github.com/spacetelescope/asdf>`__

   -  Next generation interchange format for scientific data developed
      by STScI
   -  It follows the new `ASDF
      Standard <https://asdf-standard.readthedocs.io/en/latest/>`__

-  `HDF5 - High-performance data management and storage
   suite <https://www.hdfgroup.org/solutions/hdf5/>`__

   -  In the age of big data, HDF5 format is also becoming more popular
      in astronomy. For example, many hydro-simulations use HDF5 to
      store large and complex data.
   -  `h5py is a Pythonic interface to the HDF5 binary data
      format <https://www.h5py.org/>`__
   -  `fits2hdf is a FITS to HDFITS conversion
      utility <https://github.com/telegraphic/fits2hdf>`__

-  If you use Python, it is also convenient to use the
   `pickle <https://docs.python.org/3/library/pickle.html>`__ and
   `dill <https://pypi.org/project/dill/>`__ (an even better **pickle**)
   module for serializing and de-serializing python objects to the
   majority of the built-in python types.

World Coordinate Systems (WCS)
------------------------------

-  `FITS World Coordinate System
   (WCS) <https://fits.gsfc.nasa.gov/fits_wcs.html>`__

   -  `wcslib <http://www.atnf.csiro.au/people/mcalabre/WCS/wcslib/index.html>`__
      is a C library, supplied with a full set of Fortran wrappers, that
      implements the “World Coordinate System” (WCS) standard in FITS
   -  All the tools that deals with FITS format can also deal with WCS
      information (normally stored in the header). For example, the
      `astropy.wcs <http://docs.astropy.org/en/stable/wcs/>`__

-  `Generalized World Coordinate
   System <https://gwcs.readthedocs.io/en/latest/>`__

   -  `gwcs - provides tools for managing WCS in a general
      way <https://github.com/spacetelescope/gwcs>`__

-  `stwcs - WCS based distortion models and coordinate
   transformation <https://github.com/spacetelescope/stwcs>`__
-  `tweakwcs - Algorithms for matching and aligning catalogs and for
   tweaking the WCS so as to minimize catalog mismatch
   errors <https://github.com/spacetelescope/tweakwcs>`__

   -  **tweakwcs** is a package that provides core algorithms for
      computing and applying corrections to WCS objects such as to
      minimize mismatch between image and reference catalogs. Currently
      only aligning images with FITS WCS and JWST gWCS are supported.

Astrometry and Positional Astronomy
-----------------------------------

-  `Skyfield - Elegant Astronomy for
   Python <https://rhodesmill.org/skyfield/>`__

   -  **Skyfield** computes positions for the stars, planets, and
      satellites in orbit around the Earth. Its results should agree
      with the positions generated by the United States Naval
      Observatory and their Astronomical Almanac to within 0.0005
      arcseconds. The `Github version is
      here <https://github.com/skyfielders/python-skyfield/>`__

-  `Astrometry.net – automatic recognition of astronomical
   images <https://github.com/dstndstn/astrometry.net>`__

   -  Made by Dustin Lang. The best astrometric calibration tool on the
      market.

-  `SOFA - Standard of Fundamental
   Astronomy <http://www.iausofa.org/tandc.html>`__

   -  The International Astronomical Union’s SOFA service has the task
      of establishing and maintaining an accessible and authoritative
      set of algorithms and procedures that implement standard models
      used in fundamental astronomy. The library is now in `Fortran and
      C <http://www.iausofa.org/current.html>`__
   -  `pysofa2 - A python module for wrapping the International
      Astronomical Union’s C SOFA
      libraries <https://gitlab.com/deddy/pysofa2>`__

-  `ERFA - Essential Routines for Fundamental
   Astronomy <https://github.com/liberfa/erfa>`__

   -  **ERFA** is a C library containing key algorithms for astronomy,
      and is based on the `SOFA <http://www.iausofa.org/>`__ library
      published by the International Astronomical Union (IAU).

-  `NOVAS - The United States Naval Observatory NOVAS astronomy
   library <https://github.com/brandon-rhodes/python-novas>`__

   -  **NOVAS** is an integrated package of functions for computing
      various commonly needed quantities in positional astronomy. At a
      lower level, NOVAS also provides astrometric utility
      transformations, such as those for precession, nutation,
      aberration, parallax, and gravitational deflection of light.
   -  The computations are accurate to better than one milliarcsecond.

-  `spherical_geometry - A Python package for handling spherical
   polygons that represent arbitrary regions of the
   sky <https://github.com/spacetelescope/spherical_geometry>`__

   -  Made by STScI. `Online document is
      here <https://spacetelescope.github.io/spherical_geometry/spherical_geometry/>`__

Flux standards
--------------

-  `The Absolute Magnitude of the
   Sun <http://mips.as.arizona.edu/~cnaw/sun.html>`__

   -  `Link to download the default composite spectrum of the
      Sun <http://mips.as.arizona.edu/~cnaw/sun_composite.fits>`__

-  `ESO’s RA Ordered List of Spectrophotometric
   Standards <https://www.eso.org/sci/observing/tools/standards/spectra/stanlis.html>`__
-  `NAOJ’s Optical Spectrophotometric Standard
   Stars <https://www.naoj.org/Observing/Instruments/FOCAS/Detail/UsersGuide/Observing/StandardStar/Spec/SpecStandard.html>`__
-  `ESO’s Landolt Equatorial
   Standards <http://www.eso.org/sci/observing/tools/standards/Landolt.html>`__

Plan an observation
-------------------

-  `astroplan - Python package to help astronomers plan
   observations <https://github.com/astropy/astroplan>`__
-  `iObserve <http://onekilopars.ec/iobserve/>`__

   -  The free on-line version is
      `here <https://www.arcsecond.io/iobserve>`__

-  `Object Visibility by ING <http://catserver.ing.iac.es/staralt/>`__
-  `JSkyCalc – A Convenient, Portable Observing
   Aid <https://www.dartmouth.edu/~physics/labs/skycalc/flyer.html>`__
-  `Keck telescopes’ own planning
   tool <https://www2.keck.hawaii.edu/software/obsplan/obsplan.php>`__
-  `Astronomical Observatory Sites by Latitude and
   Longitude <http://www.eso.org/~ndelmott/obs_sites.html>`__

Flux unit conversion
--------------------

-  `NICMOS Units Conversion
   Form <http://www.stsci.edu/hst/nicmos/tools/conversion_form.html>`__
-  `Magnitude/Flux Density Converter: Point
   Sources <http://ssc.spitzer.caltech.edu/warmmission/propkit/pet/magtojy/>`__

Filter Response Curves
----------------------

-  `Response curved collected in sedpy package by Ben
   Johnson <https://github.com/bd-j/sedpy/tree/master/sedpy/data/filters>`__
-  `tynt - Color filter approximations in
   Python <https://github.com/bmorris3/tynt>`__

   -  By Brett Morris. **tynt** is a super lightweight package
      containing approximate transmittance curves for more than five
      hundred astronomical filters, weighing in at just under 150 KB.
      Document can be found
      `here <https://tynt.readthedocs.io/en/latest/>`__

Extinction calculator
---------------------

-  `NED’s extinction
   calculator <https://ned.ipac.caltech.edu/extinction_calculator>`__
-  `3-D Dust Mapping with Pan-STARRS 1 <http://argonaut.skymaps.info>`__

   -  `Query service <http://argonaut.skymaps.info/query>`__

Coordinate Service
------------------

-  `RA, DEC Flexible
   converter <http://www.astrouw.edu.pl/~jskowron/ra-dec/>`__
-  `NED’s coordinate
   calculator <https://ned.ipac.caltech.edu/coordinate_calculator>`__

Managing Catalogs
-----------------

-  `astropy.table <https://docs.astropy.org/en/stable/table/>`__ is a
   flexible Python module that can handle a variant types of tables.
-  `TOPCAT - Tool for OPerations on Catalogues And
   Tables <http://www.star.bris.ac.uk/~mbt/topcat/>`__

   -  Really powerful GUI tool to deal with tables. It is written as a
      Java application.
   -  Have great functions for cross-matching catalogs, querying on-line
      databases, and making publication-grade figures.
   -  `STILTS - Starlink Tables Infrastructure Library Tool
      Set <http://www.star.bris.ac.uk/~mbt/stilts/>`__ provides most of
      **TOPCAT**\ ’s capabilities in command line.

Table cross-match
~~~~~~~~~~~~~~~~~

-  `smatch - Code to match points on the sphere using the healpix
   scheme <https://github.com/esheldon/smatch>`__

   -  By Erin Sheldon. Very fast cross-match tool, C-code wrapped in
      Python.

-  `nway - Bayesian cross-matching of astronomical
   catalogues <https://github.com/JohannesBuchner/nway>`__

   -  Bayesian match probabilities based on astronomical sky coordinates
      (RA, DEC)

-  `C3 - Command-line Catalogue Cross-matching
   Tool <http://dame.dsf.unina.it/c3.html>`__
-  `xmatch - Cross match of
   catalogs <https://git.ias.u-psud.fr/abeelen/xmatch>`__

   -  By Alexandre Beelen.

Cosmology Calculator
--------------------

-  `ICRAR’s Cosmology Calculator <http://cosmocalc.icrar.org>`__

   -  Based on the `celestial
      R-code <https://github.com/asgr/celestial>`__

-  `Ned Wright’s Cosmology
   Calculator <http://www.astro.ucla.edu/%7Ewright/CosmoCalc.html>`__

Simulate Galaxy Spectrum
------------------------

-  `SpecGen - Mock Galaxy Spectra
   Generator <http://specgen.icrar.org>`__

Sky Projection Maps of Surveys
------------------------------

-  `AstroMap - generating sky projection maps for astronomical
   surveys <http://astromap.icrar.org>`__

List of Observatories
---------------------

-  `List of Astronomical Observatories on
   Wiki <https://en.wikipedia.org/wiki/List_of_astronomical_observatories>`__

-  `Observatories by
   GoAstronomy <https://www.go-astronomy.com/observatories.htm>`__

   -  Including U.S observatories and observatories worldwide.

Basic Astronomy Database
------------------------

-  `SIMBAD Astronomical Database -
   CDS <http://simbad.u-strasbg.fr/simbad/>`__

   -  The **SIMBAD** astronomical database provides basic data,
      cross-identifications, bibliography and measurements for
      astronomical objects outside the solar system.

-  `VizieR Catalog
   Database <http://vizier.u-strasbg.fr/viz-bin/VizieR>`__

   -  **VizieR** provides the most complete library of published
      astronomical catalogues -tables and associated data- with verified
      and enriched data, accessible via multiple interfaces.

-  `Aladin Sky Atlas <https://aladin.u-strasbg.fr/aladin.gml#>`__

   -  **Aladin** is an interactive sky atlas allowing the user to
      visualize digitized astronomical images or full surveys,
      superimpose entries from astronomical catalogues or databases, and
      interactively access related data and information from the Simbad
      database, the VizieR service and other archives for all known
      astronomical objects in the field.

-  `NASA/IPAC Extragalactic Database <https://ned.ipac.caltech.edu/>`__

   -  **NED** is a comprehensive database of multiwavelength data for
      extragalactic objects, providing a systematic, ongoing fusion of
      information integrated from hundreds of large sky surveys and tens
      of thousands of research publications.

-  `NASA/IPAC Infrared Science
   Archive <https://irsa.ipac.caltech.edu/frontpage/>`__

   -  **IRSA** is chartered to curate the science products of NASA’s
      infrared and submillimeter missions, including many large-area and
      all-sky surveys.

-  `MAST - Mikulski Archive for Space
   Telescopes <http://archive.stsci.edu/>`__

   -  **MAST** provides a variety of astronomical archives focused on
      scientific data sets in the optical, ultraviolet, and
      near-infrared parts of the spectrum.
   -  `The MAST
      Portal <https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html>`__
      lets you search multiple collections of astronomical datasets all
      in one place.