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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

3615 results found.

  1. LIGO/Virgo S190425z: Palomar Gattini-IR wide-field infrared follow-up
  2. LIGO/Virgo S190425z: AGILE-GRID Observations
  3. LIGO/Virgo S190425z: Fermi GBM Observations
  4. LIGO/Virgo S190425z: Swift/BAT Counterpart Search
  5. LIGO/Virgo S190425z: SQUEAN Observation
  6. LIGO/Virgo S190425z: MMT Follow-Up Observations
  7. LIGO/Virgo S190425z: INTEGRAL IBIS prompt observation
  8. LIGO-Virgo S190425z: AGILE MCAL observation
  9. LIGO/Virgo S190425z: Lick/KAIT Follow-Up Observations
  10. LIGO/Virgo S190425z: further analysis of INTEGRAL data
  11. LIGO/Virgo S190425z: MAXI/GSC Observations
  12. LIGO/VIRGO S190425z: IceCube Neutrino Search
  13. LIGO/Virgo S190425z: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  14. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  15. LIGO/VirgoS190425z: HAWC follow-up
  16. LIGO/Virgo S190425z: SAGUARO follow-up observations
  17. LIGO/Virgo S190425z: Potential host galaxies from the GLADE catalog
  18. LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
  19. LIGO/Virgo S190425z: INTEGRAL prompt observation
  20. LIGO/Virgo S190425z: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo S190425z Global MASTER-Net observations report
  22. LIGO-Virgo S190421ar:Insight-HXMT/HE observation
  23. LIGO/Virgo S190421ar: TAROT-GRANDMA observation report.
  24. LIGO/Virgo S190421ar: Lick/KAIT Follow-Up Observations
  25. LIGO/Virgo S190421ar: Swift/BAT Counterpart Search
  26. LIGO/Virgo S190421ar/G330308: ANTARES neutrino search
  27. LIGO/Virgo S190408an: Liverpool Telescope follow-up imaging observations
  28. LIGO/Virgo S190421ar: MAXI/GSC Observations
  29. LIGO/Virgo S190421ar: INTEGRAL prompt observation
  30. LIGO/Virgo S190421ar: Fermi-GBM Observations
  31. LIGO/Virgo S190421ar Global MASTER-Net observations report
  32. LIGO/Virgo S190421ar: HAWC follow-up
  33. AT LIGO-Virgo S190421ar: AGILE GRID observations
  34. LIGO/VIRGO S190421ar: IceCube Neutrino Search
  35. LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate
  36. LIGO-Virgo S190421ar: AGILE MCAL observations
  37. LIGO/Virgo S190408an: INTEGRAL follow-up observations
  38. LIGO/Virgo S190412m: SVOM/GWAC observations of the initial skymap
  39. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidates
  40. LIGO/Virgo S190412m: TAROT-GRANDMA observation report.
  41. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  42. LIGO/Virgo S190412m: Palomar Gattini-IR Wide-field Infrared Follow-up
  43. LIGO/Virgo S190412m: GOTO optical coverage - no notable counterparts
  44. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  45. LIGO/Virgo S190412m: Swift/BAT data search
  46. LIGO/Virgo S190412m: J-GEM optical/NIR follow-up observations
  47. LIGO/Virgo S190412m: Fermi-GBM Observations
  48. LIGO/Virgo S190412m: MAXI/GSC Observations
  49. LIGO-Virgo S190412m: AGILE GRID observations
  50. LIGO/Virgo S190405ar: Retraction of a GW binary merger candidate
  51. LIGO/Virgo S190412m: Insight-HXMT/HE observation
  52. LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
  53. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  54. LIGO/Virgo S190412m/G329483: ANTARES neutrino search
  55. LIGO/Virgo S190412m: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  56. LIGO-Virgo S190412m: Search for neutrino counterparts with IceCube
  57. LIGO/Virgo S190412m: HAWC follow-up
  58. LIGO-Virgo S190412m: AGILE preliminary analysis
  59. LIGO/Virgo S190412m: MASTER early alert observation
  60. LIGO/Virgo S190412m: Identification of a GW binary merger candidate
  61. LIGO/Virgo S190408an: GROND Observations of MASTER OT J154209.55-431742.2
  62. LIGO/Virgo S190408an: Pan-STARRS observations and transients in the skymap
  63. LIGO/Virgo S190408an: MASTER OT J231043.63+470956.4 BOOTES-4 and 10.4m GTC follow-up observations
  64. LIGO/Virgo S190408an: MAXI/GSC Observations
  65. LIGO/Virgo S190408an: GRAWITA optical observations of MASTER OT J231043.63+470956.4
  66. LIGO/Virgo S190408an: CALET Observations
  67. LIGO/Virgo S190408an: TMTS Optical Observation
  68. LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
  69. LIGO/Virgo S190408an: HMT optical observations
  70. LIGO/Virgo S190408an: MASTER 3 OT's more detection
  71. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  72. LIGO-Virgo S190408an: further AGILE GRID observations after T0
  73. LIGO/Virgo S190408an: SAGUARO follow-up observations
  74. LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
  75. LIGO/Virgo S190408an: Insight-HXMT/HE observation
  76. LIGO/Virgo S190408an: MASTER OT detection
  77. LIGO/Virgo S190408an: Swift/BAT data search
  78. LIGO/Virgo S190408an: KMTNet observation
  79. LIGO-Virgo S190408an: AGILE GRID observations
  80. LIGO/Virgo S190408an: MASTER Global Robotic Net optical observations
  81. LIGO/Virgo S190408an: Identification of a GW binary merger candidate
  82. LIGO-Virgo S190408an: HAWC follow-up
  83. LIGO/Virgo S190408an: Fermi GBM Observation
  84. LIGO-Virgo GW S190408an: J-GEM optical/NIR follow-up observations
  85. LIGO-Virgo S190408an: AGILE MCAL observations
  86. LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
  87. INTEGRAL observations of the events in the GWTC-1 catalog
  88. Fermi-GBM Observations During Four New GW-Detected BBH Mergers (Correction)
  89. Fermi-GBM Observations During Four New GW-Detected BBH Mergers
  90. GRB 180728B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 554505003)
  91. GRB180913A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 558557292)
  92. LIGO/Virgo GW170817: A steep decline in the radio light curve and prediction for the X-rays
  93. GRB 180626C: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 551697835)
  94. LIGO/Virgo G299232: LOFAR follow-up
  95. LIGO/Virgo GW170817: Chandra X-ray Emission Continues to Rise ~156 Days Post-Merger
  96. LIGO/Virgo G298048 GRAWITA: VST-ESO PARANAL follow up of AT2017gfo
  97. LIGO/Virgo GW170817: X-ray observations confirm prediction made from radio data
  98. LIGO/Virgo GW170817: Further Hubble Space Telescope observations
  99. LIGO/Virgo G298048: Brightening X-ray Emission from GW170817/GRB170817A/SSS17a
  100. LIGO/Virgo GW170817: Chandra X-ray brightening of the counterpart 108 days since merger

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