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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"

4714 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 230203275 / 697098930 is not a GRB
  2. Fermi trigger No 697098930: Global MASTER-Net observations report
  3. Fermi GRB 230201B: Global MASTER-Net observations report
  4. Fermi GRB 230201A: Global MASTER-Net observations report
  5. IceCube-230122A: BOOTES-2/TELMA Optical Upper Limit
  6. AT2023avj ZTF Candidate: Assy optical observations
  7. IceCube-230122A: Upper limits from a search for additional neutrino events in IceCube
  8. Fermi-LAT gamma-ray observations of IceCube-230122A
  9. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  10. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  11. Fermi trigger No 695057654: Global MASTER-Net observations report
  12. GRB 230104A: AGILE/MCAL detection of a burst
  13. GRB 221230A: CALET Gamma-Ray Burst Monitor detection
  14. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  15. Fermi GRB 221221A: Global MASTER-Net observations report
  16. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  17. Fermi trigger No 692713692: Global MASTER-Net observations report
  18. Swift Trigger 1144538 is not a GRB
  19. Fermi GRB 221211A: Global MASTER-Net observations report
  20. GRB 221208A: AstroSat CZTI detection
  21. GRB 221209B: Fermi GBM Final Real-time Localization
  22. GRB 221203C: AstroSat CZTI detection
  23. GRB 221202B: Detection by VZLUSAT-2
  24. GRB 221202A: MeerLICHT upper limits
  25. IceCube Alert 221124.66: Global MASTER-Net observations report
  26. GRB 221115A: Fermi GBM detection
  27. GRB 221110A: COATLI Second-Epoch Upper Limits
  28. GRB 221110A: COATLI Afterglow detection
  29. GRB 221110A: LCOGT Optical Afterglow Detection
  30. IceCube-221104A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 221028A: COATLI Upper Limits
  32. GRB 221028A: Swift detection of a burst
  33. GRB 221024A: Mondy optical observations
  34. IPN triangulation of GRB 221022C (short)
  35. LAT GRB221025.04: Global MASTER-Net observations report
  36. GRB221009A: LBT optical imaging
  37. AGILE detection of short X-ray flaring activity contemporary to SGR J1935+2154 reported bursts
  38. GRB 221017A: MAXI/GSC detection
  39. GRB 221009A: Armchair Energetics
  40. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  41. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  42. Fermi trigger No 687345829: Global MASTER-Net observations report
  43. Fermi trigger No 687344475: Global MASTER-Net observations report
  44. Fermi trigger No 687340841: Global MASTER-Net observations report
  45. Fermi trigger No 687337536: Global MASTER-Net observations report
  46. Fermi trigger No 687281393: Global MASTER-Net observations report
  47. GRB 221009A/Swift J1913.1+1946: SMA observations
  48. GRB 221009A: NuSTAR Detection
  49. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  50. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  51. GRB 221009A: Fermi-LAT refined analysis
  52. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  53. Fermi trigger No 687014224: Global MASTER-Net observations report
  54. Fermi trigger No 686403226: Global MASTER-Net observations report
  55. Fermi trigger No 686350260: Global MASTER-Net observations report
  56. Ultra-long GRB 220525B: Konus-Wind and Fermi-GBM detection
  57. Fermi GRB 220925A: Global MASTER-Net observations report
  58. Fermi trigger No 685748699: Global MASTER-Net observations report
  59. Fermi trigger No 684894705: Global MASTER-Net observations report
  60. IceCube-220907A: No significant detection in HAWC
  61. Fermi GRB 220912A: Global MASTER-Net observations report
  62. GRB 220831A: Gemini-South Infrared Observations
  63. IceCube-220907A: One Candidate Counterpart from the Zwicky Transient Facility
  64. IceCube Alert 220907.28: Global MASTER-Net observations report
  65. Fermi GRB 220902A: Global MASTER-Net observations report
  66. Fermi trigger No 683654200: Global MASTER-Net observations report
  67. GRB 220827A: Fermi GBM Final Real-time Localization
  68. Fermi trigger No 683202084: Global MASTER-Net observations report
  69. Fermi trigger No 683183601: Global MASTER-Net observations report
  70. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  71. GRB 220823A: Fermi GBM detection
  72. Fermi trigger No 682918137: Global MASTER-Net observations report
  73. GRB 220813A: Swift detection of a burst with an optical counterpart
  74. Fermi trigger No 681890304: Global MASTER-Net observations report
  75. Fermi trigger No 681719116: Global MASTER-Net observations report
  76. Fermi trigger No 681633544: Global MASTER-Net observations report
  77. Fermi trigger No 681271717: Global MASTER-Net observations report
  78. GRB 220803A: AstroSat CZTI detection
  79. Fermi trigger No 681212354: Global MASTER-Net observations report
  80. Fermi trigger No 680782656: Global MASTER-Net observations report
  81. Fermi GRB 220728A: Global MASTER-Net observations report
  82. Fermi trigger No 680421061: Global MASTER-Net observations report
  83. GRB 220724A: Fermi GBM Final Real-time Localization
  84. GRB 220714B: UVOT afterglow discovery
  85. Fermi GRB 220711B: Global MASTER-Net observations report
  86. GRB 220706A : NICER detection of re-brightening 1 day after the Swift trigger
  87. GRB 220701A: COATLI Optical Upper Limit
  88. IceCube-220629A: No significant detection in HAWC
  89. IceCube-220627A: No significant detection in HAWC
  90. IceCube Alert 220627.74: Global MASTER-Net observations report
  91. GRB 220623A: BOOTES-5/JGT optical afterglow detection
  92. Swift GRB220620.02: Global MASTER-Net observations report
  93. Fermi trigger No 677307509: Global MASTER-Net observations report
  94. IPN triangulation of GRB 220606C
  95. Fermi trigger No 676909037: Global MASTER-Net observations report
  96. GRB 220608A: AstroSat CZTI detection
  97. Fermi GRB 220608A: Global MASTER-Net observations report
  98. GRB 220608A: Fermi GBM Final Real-time Localization
  99. GRB 220606B: Fermi GBM Observation
  100. GRB 220606B: Swift/BAT-GUANO candidate arcminute localization of a short burst

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