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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').
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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"

4057 results found.

  1. LIGO/Virgo S190425z: SQUEAN Observation
  2. LIGO/Virgo S190425z: MMT Follow-Up Observations
  3. LIGO/Virgo S190425z: INTEGRAL IBIS prompt observation
  4. LIGO-Virgo S190425z: AGILE MCAL observation
  5. LIGO/Virgo S190425z: Lick/KAIT Follow-Up Observations
  6. LIGO/Virgo S190425z: further analysis of INTEGRAL data
  7. LIGO/Virgo S190425z: MAXI/GSC Observations
  8. LIGO/VIRGO S190425z: IceCube Neutrino Search
  9. LIGO/Virgo S190425z: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  10. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  11. LIGO/VirgoS190425z: HAWC follow-up
  12. LIGO/Virgo S190425z: SAGUARO follow-up observations
  13. LIGO/Virgo S190425z: Potential host galaxies from the GLADE catalog
  14. LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
  15. LIGO/Virgo S190425z: INTEGRAL prompt observation
  16. LIGO/Virgo S190425z: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo S190425z Global MASTER-Net observations report
  18. LIGO-Virgo S190421ar:Insight-HXMT/HE observation
  19. LIGO/Virgo S190421ar: TAROT-GRANDMA observation report.
  20. LIGO/Virgo S190421ar: Lick/KAIT Follow-Up Observations
  21. LIGO/Virgo S190421ar: Swift/BAT Counterpart Search
  22. LIGO/Virgo S190421ar/G330308: ANTARES neutrino search
  23. LIGO/Virgo S190408an: Liverpool Telescope follow-up imaging observations
  24. LIGO/Virgo S190421ar: MAXI/GSC Observations
  25. LIGO/Virgo S190421ar: INTEGRAL prompt observation
  26. LIGO/Virgo S190421ar: Fermi-GBM Observations
  27. LIGO/Virgo S190421ar Global MASTER-Net observations report
  28. LIGO/Virgo S190421ar: HAWC follow-up
  29. AT LIGO-Virgo S190421ar: AGILE GRID observations
  30. LIGO/VIRGO S190421ar: IceCube Neutrino Search
  31. LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate
  32. LIGO-Virgo S190421ar: AGILE MCAL observations
  33. LIGO/Virgo S190408an: INTEGRAL follow-up observations
  34. LIGO/Virgo S190412m: SVOM/GWAC observations of the initial skymap
  35. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidates
  36. LIGO/Virgo S190412m: TAROT-GRANDMA observation report.
  37. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  38. LIGO/Virgo S190412m: Palomar Gattini-IR Wide-field Infrared Follow-up
  39. LIGO/Virgo S190412m: GOTO optical coverage - no notable counterparts
  40. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  41. LIGO/Virgo S190412m: Swift/BAT data search
  42. LIGO/Virgo S190412m: J-GEM optical/NIR follow-up observations
  43. LIGO/Virgo S190412m: Fermi-GBM Observations
  44. LIGO/Virgo S190412m: MAXI/GSC Observations
  45. LIGO-Virgo S190412m: AGILE GRID observations
  46. LIGO/Virgo S190405ar: Retraction of a GW binary merger candidate
  47. LIGO/Virgo S190412m: Insight-HXMT/HE observation
  48. LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
  49. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  50. LIGO/Virgo S190412m/G329483: ANTARES neutrino search
  51. LIGO/Virgo S190412m: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  52. LIGO-Virgo S190412m: Search for neutrino counterparts with IceCube
  53. LIGO/Virgo S190412m: HAWC follow-up
  54. LIGO-Virgo S190412m: AGILE preliminary analysis
  55. LIGO/Virgo S190412m: MASTER early alert observation
  56. LIGO/Virgo S190412m: Identification of a GW binary merger candidate
  57. LIGO/Virgo S190408an: GROND Observations of MASTER OT J154209.55-431742.2
  58. LIGO/Virgo S190408an: Pan-STARRS observations and transients in the skymap
  59. LIGO/Virgo S190408an: MASTER OT J231043.63+470956.4 BOOTES-4 and 10.4m GTC follow-up observations
  60. LIGO/Virgo S190408an: MAXI/GSC Observations
  61. LIGO/Virgo S190408an: GRAWITA optical observations of MASTER OT J231043.63+470956.4
  62. LIGO/Virgo S190408an: CALET Observations
  63. LIGO/Virgo S190408an: TMTS Optical Observation
  64. LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
  65. LIGO/Virgo S190408an: HMT optical observations
  66. LIGO/Virgo S190408an: MASTER 3 OT's more detection
  67. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  68. LIGO-Virgo S190408an: further AGILE GRID observations after T0
  69. LIGO/Virgo S190408an: SAGUARO follow-up observations
  70. LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
  71. LIGO/Virgo S190408an: Insight-HXMT/HE observation
  72. LIGO/Virgo S190408an: MASTER OT detection
  73. LIGO/Virgo S190408an: Swift/BAT data search
  74. LIGO/Virgo S190408an: KMTNet observation
  75. LIGO-Virgo S190408an: AGILE GRID observations
  76. LIGO/Virgo S190408an: MASTER Global Robotic Net optical observations
  77. LIGO/Virgo S190408an: Identification of a GW binary merger candidate
  78. LIGO-Virgo S190408an: HAWC follow-up
  79. LIGO/Virgo S190408an: Fermi GBM Observation
  80. LIGO-Virgo GW S190408an: J-GEM optical/NIR follow-up observations
  81. LIGO-Virgo S190408an: AGILE MCAL observations
  82. LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
  83. IPN Triangulation of GRB 190329A (long/bright)
  84. GRB 190114C: photometric detection of a SN component
  85. Improved Fermi/GBM GRB localizations
  86. IPN Triangulation of GRB 190304A (long)
  87. IPN Triangulation of GRB 190206A (short/extremely bright)
  88. GRB 190204A: Swift-BAT refined analysis
  89. IPN Triangulation of GRB 190129B (long/extremely bright)
  90. IPN Triangulation of GRB 190118A (long)
  91. CALET Gamma-Ray Burst Monitor: Policy change in the GCN circulars
  92. INTEGRAL observations of the events in the GWTC-1 catalog
  93. Fermi-GBM Observations During Four New GW-Detected BBH Mergers (Correction)
  94. Fermi-GBM Observations During Four New GW-Detected BBH Mergers
  95. IPN Triangulation of GRB 181121A (short)
  96. GRB 180728B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 554505003)
  97. GRB180913A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 558557292)
  98. IPN Triangulation of GRB 181008B (long)
  99. IPN Triangulation of GRB 180824A (short)
  100. LIGO/Virgo GW170817: A steep decline in the radio light curve and prediction for the X-rays

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