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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"

12307 results found.

  1. Fermi GRB 260907A: Global MASTER-Net observations report
  2. GRB 260907A: Fermi GBM Final Real-time Localization
  3. GRB 260831A: GECAM-B observation
  4. GRB 260827A: Insight-HXMT/HE detection
  5. Konus-Wind detection of GRB 260829A
  6. GRB 260829A: SVOM/GRM observation
  7. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  8. GRB 260829A: AstroSat CZTI detection
  9. GRB 260827A: SVOM/GRM observation
  10. IPN triangulation of GRB 260829A
  11. GRB 260827A: Glowbug gamma-ray detection
  12. GRB 260831A: Fermi GBM Final Real-time Localization
  13. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  14. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  15. GRB 260829A: GECAM-B observation of a long burst
  16. GRB 260825A: SVOM/GRM observation of a long burst
  17. GRB 260825A: GECAM-B observation
  18. GRB 260829A: Fermi GBM Detection
  19. GRB 260825A: AstroSat CZTI detection
  20. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  21. GRB 260829A: Fermi GBM Final Real-time Localization
  22. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  23. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  25. Fermi GBM trigger 809666623/260829141 is not a GRB
  26. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 260827A: Fermi GBM Final Real-time Localization
  28. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  29. GRB 260809A: SVOM/ECLAIRs refined analysis
  30. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 260825A: Fermi GBM Final Real-time Localization
  32. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB260822B: Fermi GBM Final Localization
  34. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  35. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  36. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 260820A: Insight-HXMT/HE detection
  38. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  39. GRB260820A: Fermi GBM Final Real-Time Localization
  40. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  41. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  42. GRB 260813A: Fermi GBM Final Real-time Localization
  43. GRB 260808A: SVOM/GRM observation
  44. Fermi GBM Sub-Threshold Detection of GRB 260809A
  45. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  46. GRB 260808A: GECAM-B observation
  47. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  49. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  50. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  51. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 260808A: NuSTAR detection of prompt emission
  53. GRB 260808C: Fermi GBM Final Real-time Localization
  54. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  55. Fermi GRB 260808A: Global MASTER-Net observations report
  56. GRB 260808A: Fermi GBM Final Real-time Localization
  57. IceCube-260805A: One candidate from the Zwicky Transient Facility
  58. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 260715A: cubesat Avion detection
  60. GRB 260709A: cubesat Avion detection
  61. GRB 260708A: cubesat Avion detection
  62. SN 2026stf / GRB 260708A: ATLAS forced photometry
  63. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 260805B: Glowbug gamma-ray detection
  65. Fermi GRB 260805A: Global MASTER-Net observations report
  66. GRB 260805B: Fermi GBM Final Localization
  67. GRB 260804A: Glowbug gamma-ray detection
  68. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  69. GRB 260805A: Fermi GBM Final Localization
  70. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  71. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 260804A: Fermi GBM Final Real-time Localization
  73. GRB 260708A: LCO further optical observations show supernova features
  74. GRB 260803A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 260802B: Global MASTER-Net observations report
  76. GRB 260802B: Fermi GBM Final Localization
  77. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  78. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  79. GRB 260726A: SVOM/ECLAIRs refined analysis
  80. GRB260730A: Fermi GBM Final Localization
  81. GRB 260726A: EP-FXT follow-up observations
  82. GRB 260726A: Fermi GBM Observation
  83. GRB 260726A: Liverpool Telescope optical observations
  84. GRB 260728A: Fermi GBM Final Localization
  85. GRB 260726A: J-band upper limit with WINTER
  86. GRB 260726A: SVOM/VT optical candidate
  87. GRB 260727B: Fermi GBM Final Real-time Localization
  88. Fermi GRB 260726A: Global MASTER-Net observations report
  89. GRB 260726A: SVOM detection of a burst
  90. GRB 260726A: Fermi GBM Final Real-time Localization
  91. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  92. GRB 260616A: cubesat Avion detection
  93. GRB 260602B: cubesat Avion detection
  94. GRB 260601A: cubesat Avion detection
  95. GRB 260718A: SVOM/ECLAIRs refined analysis
  96. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  97. GRB 260723A: Fermi GBM Final Localization
  98. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  100. GRB 260722A: Fermi GBM Final Real-time Localization

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