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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"

12283 results found.

  1. Fermi GBM trigger 809666623/260829141 is not a GRB
  2. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  3. GRB 260827A: Fermi GBM Final Real-time Localization
  4. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  5. GRB 260809A: SVOM/ECLAIRs refined analysis
  6. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 260825A: Fermi GBM Final Real-time Localization
  8. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB260822B: Fermi GBM Final Localization
  10. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  11. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  12. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 260820A: Insight-HXMT/HE detection
  14. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  15. GRB260820A: Fermi GBM Final Real-Time Localization
  16. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  17. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  18. GRB 260813A: Fermi GBM Final Real-time Localization
  19. GRB 260808A: SVOM/GRM observation
  20. Fermi GBM Sub-Threshold Detection of GRB 260809A
  21. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  22. GRB 260808A: GECAM-B observation
  23. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  25. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  26. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  27. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 260808A: NuSTAR detection of prompt emission
  29. GRB 260808C: Fermi GBM Final Real-time Localization
  30. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  31. Fermi GRB 260808A: Global MASTER-Net observations report
  32. GRB 260808A: Fermi GBM Final Real-time Localization
  33. IceCube-260805A: One candidate from the Zwicky Transient Facility
  34. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 260715A: cubesat Avion detection
  36. GRB 260709A: cubesat Avion detection
  37. GRB 260708A: cubesat Avion detection
  38. SN 2026stf / GRB 260708A: ATLAS forced photometry
  39. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260805B: Glowbug gamma-ray detection
  41. Fermi GRB 260805A: Global MASTER-Net observations report
  42. GRB 260805B: Fermi GBM Final Localization
  43. GRB 260804A: Glowbug gamma-ray detection
  44. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  45. GRB 260805A: Fermi GBM Final Localization
  46. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  47. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 260804A: Fermi GBM Final Real-time Localization
  49. GRB 260708A: LCO further optical observations show supernova features
  50. GRB 260803A: Fermi GBM Final Real-time Localization
  51. Fermi GRB 260802B: Global MASTER-Net observations report
  52. GRB 260802B: Fermi GBM Final Localization
  53. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  54. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  55. GRB 260726A: SVOM/ECLAIRs refined analysis
  56. GRB260730A: Fermi GBM Final Localization
  57. GRB 260726A: EP-FXT follow-up observations
  58. GRB 260726A: Fermi GBM Observation
  59. GRB 260726A: Liverpool Telescope optical observations
  60. GRB 260728A: Fermi GBM Final Localization
  61. GRB 260726A: J-band upper limit with WINTER
  62. GRB 260726A: SVOM/VT optical candidate
  63. GRB 260727B: Fermi GBM Final Real-time Localization
  64. Fermi GRB 260726A: Global MASTER-Net observations report
  65. GRB 260726A: SVOM detection of a burst
  66. GRB 260726A: Fermi GBM Final Real-time Localization
  67. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  68. GRB 260616A: cubesat Avion detection
  69. GRB 260602B: cubesat Avion detection
  70. GRB 260601A: cubesat Avion detection
  71. GRB 260718A: SVOM/ECLAIRs refined analysis
  72. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  73. GRB 260723A: Fermi GBM Final Localization
  74. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  75. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  76. GRB 260722A: Fermi GBM Final Real-time Localization
  77. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  78. Fermi GBM trigger 806384210/260722151 is not a GRB
  79. Konus-Wind detection of GRB 260714B
  80. GRB 260714B: Insight-HXMT/HE detection
  81. GRB 260718A: EP-FXT follow-up observation
  82. Fermi trigger No 806104130: Global MASTER-Net observations report
  83. Fermi GRB 260718A: Global MASTER-Net observations report
  84. GRB 260718A: LCO optical upper limits
  85. GRB 260710A: SVOM/GRM observation
  86. GRB 260718A: Fermi GBM Observation
  87. GRB 260714B: SVOM/GRM observation
  88. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  89. GRB 260714B: GECAM-B observation of a burst
  90. GRB 260618B: EP-FXT follow-up observation upper limit
  91. GRB 260714B: COLIBRÍ optical counterpart candidate
  92. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  93. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  94. GRB 260715A: Fermi GBM Final Real-time Localization
  95. GRB 260710A: AstroSat CZTI detection
  96. GRB 260709A: AstroSat CZTI detection
  97. GRB 260714B: AstroSat CZTI detection
  98. GRB 260714B: Fermi-LAT detection
  99. GRB 260714B: Fermi GBM Detection
  100. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)

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