resources

EM Spectrum in Astronomy from Astrobites

I created a mindmap from the information above

Radio
λ > 1 mm
ν < 300 GHz
- Objects
  - AGN JEts
  - Supernovae
  - Tidal Disruption Events
  - H II regions
  - Gamma ray bursts
  - Radio Galaxies
- Processes
  - Synchrotron radiation
  - Free-free radiation
- Observation
  - Ground based
- Telescopes
  - Green Bank Telescope (GBT)
  - Five-hundred-meter Aperture Spherical Telescope (FAST)
  - Very Large Array (VLA)
  - Square Kilometer Array (SKA)
  - Low-Frequency Array (LoFAR),
  - Giant Meterwave Radio Telescope (GMRT)

Microwave/Sub-mm
λ ~ 300 μm to 1 mm
ν ~ 1 THz to 300 GHz
- Objects
  - CMB
  - High energy phenomena
    - Relativistic jets
    - Cold dust
    - Cold gas
    - Galaxies at high z
- Processes
  - Thermal (blackbody radiation)
- Observation
  - Space
  - Ground
- Telescopes
  - Space
    - Cosmic Background Explorer (COBE)
    - Wilkinson Microwave Anisotropy Probe (WMAP)
    - Planck
  - Ground
    - Submillimeter Array (SMA
    - Atacama Large Millimeter/submillimeter Array (ALMA).

Infrared
λ ~ 300 μm to 2.5 μm
ν ~ 1 THz to 120 THz
- Far-Infrared
  λ ~ 15 μm to 300 μm
  ν ~ 20 THz 1 THz
  - Objects
    - Cool dust
    - Cool gas
    - star forming galaxies
    - young stellar objects
      - proto-stars
      - pre-main sequence stars
  - Processes
    - Thermal (Blackbody radiation)
  - Observation
    - Space
  - Telescopes
    - Infrared Astronomical Satellite (IRAS)
    - Infrared Space Observatory (ISO)
    - Herschel
- Mid-Infrared
  λ ~ 2.5 μm to 15 μm
  ν ~ 120 THz 20 THz
  - Objects
    - Cosmic dust
      - surrounding young stars
      - protoplanetary disks
      - zodiacal dust
    - Solar system objects
      - planets
      - comets
      - asteroids
  - Processes
    - Thermal (Blackbody Radiation)
  - Observation
    - Space
    - Ground
  - Telescopes
    - Ground
      - Infrared Telescope Facility (IRTF)
      - United Kingdom Infrared Telescope (UKIRT)
    - Space
      - James Webb Space Telescope
      - Wide-field Infrared Survey Explorer (WISE)
      - Spitzer
- Near-Infrared
  λ ~ 0.8 μm to 2.5 μm
  ν ~ 380 THz 120 THz
  - Objects
    - M-dwarfs
    - Cool stars
    - Low-mass stars
    - Galaxies
  - Processes
    - Thermal (Blackbody Radiation)
  - Observation
    - Space
    - Ground
  - Telescopes
    - Ground
      - 2MASS survey
      - Infrared Telescope Facility (IRTF)
      - United Kingdom Infrared Telescope (UKIRT)
      - Visible and Infrared Survey Telescope for Astronomy (VISTA)
    - Space
      - James Webb Space Telescope

Optical
λ ~ 350 nm to 800 nm
ν ~ 860 THz 380 THz
- Objects
  - Ionized gases
  - Stars
  - Galaxies
- Processes
  - Black Body Radiation (Thermal)
  - Non-thermal
- Observation
  - Both Ground and Space
- Telescopes
  - Ground
    - W.M. Keck telescopes
    - Very Large Telescopes
    - Southern African Large Telescope (SALT)
  - Space
    - Hubble Space Telescope
    - Gaia
    - Kepler
    - Transiting Exoplanet Survey Satellite (TESS).

Ultra-violet
λ ~ 10 nm to 350 nm
ν ~ 3e16 Hz to 860 Hz
E ~ 120 eV to 3.5 eV
- Objects
  - Thermal
    - O Stars
    - B Stars
    - white dwarfs
  - Non-thermal
    - AGN (continuous emission)
- Processes
  - Blackbody radiation (thermal radiation)
  - Non-thermal sources
- Observation
  - Ground (longest)
  - Space
- Telescopes
  - AstroSAT (2015)
  - Galaxy Evolution Explorer (GALEX) (2003)
  - Hubble Space Telescope (1990)
  - Neil Gehrels Swift Observatory (2004)

X-Ray
λ ~ 10 pm to 10 nm
ν ~ 3e19 Hz to 3e16 Hz
E ~ 120 keV to 0.12 keV
- Objects
  - X-Ray binaries
  - AGN
  - Neutron stars
- Processes
  - Thermal Emission
  - Free-Free emission
  - Accretion
- Observation
  - From Space
- Telescopes
  - Uhuru (1973)
  - Einstein (1978-81)
  - ROSAT (1999)
  - Chandra (1999)
  - XMM-Newton (1999)
  - NuSTAR (2012)
  - eROSITA (2019)

- Gamma-Ray
  λ < 10 pm
  ν > 3e19 Hz
  E > 120 keV
  - Objects
    - AGN with Relativistic Jets
    - Gamma Ray Binaries
    - Gamma Ray Bursts
  - Processes
    - Gamma Decay
    - Pair-Annihilation
    - Shock Waves
    - Inverse-Compton Scattering
  - Observation
    - From Space
  - Telescopes
    - Compton Gamma-ray Observatory (1991)
    - International Gamma-Ray Astrophysics Laboratory (INTEGRAL) (2002)
    - Fermi (2008)

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Finding a good and accurate graphic or illustration for your need is something that we all struggle with. On top of that if the requirement is that the graphic resource has to be free (as in freedom) then it further narrows down the options. Sometimes you see the graphic you want, but its license terms are unknown or are not agreeable to your work as they are not released freely. So what do you do? Either you use an illustration which is not perfect fit or you use one which breaks your resource (in terms of license). But the problems is also that there are many free resource repositories which are very well not known. I have personally come across great many graphic resources, only to be forgotten after their current need is finished. This post is an attempt to overcome this. This post is a collection of various free graphics and illustration resources and repositories that I have found useful over the years. It is also a sort of personal bookmark list of the these resources if and when I need them in the future. I hope this will be of use to others too. I will keep on updating this list with new resources that I find. If you know of any resources which are missing please do post in the comments.

The Internet Archive Image Search https://archive.org/details/image

Wikimedia Commons https://commons.wikimedia.org/

Open source illustrations kit https://illlustrations.co/

NYPL Public Domain Archive https://nypl.getarchive.net

David Rumsey Map Collection https://www.davidrumsey.com/ also https://archive.org/details/david-rumsey-map-collection

Metropolitan Museum of Arts Public Domain Images also https://archive.org/details/metropolitanmuseumofart-gallery

Cleveland Museum of Art Open Access also https://archive.org/details/clevelandart

Brooklyn Museum also https://archive.org/details/brooklynmuseum

https://archive.org/details/bibliothequesaintegenevieve_image

Unsplash Free Images

NASA Images

ESO Images