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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

37674 results found.

  1. GRB 260127B: GECAM-B observation of a short burst
  2. GRB 260127A: GECAM-B observation
  3. GRB 260131A: NOT spectroscopic redshift z = 1.434
  4. Konus-Wind detection of GRB 260128A / EP260128a
  5. GRB 260131A: Insight-HXMT/HE detection
  6. Konus-Wind detection of GRB 260131A/B
  7. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  8. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  9. GRB 260131A/B: Fermi GBM Observation
  10. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  11. GRB 260131B: MAXI/GSC detection
  12. GRB 260131A: Fermi GBM Final Real-time Localization
  13. GRB 260127B: AstroSat CZTI detection
  14. GRB 260130A: Fermi GBM Detection
  15. GRB 260127B: Fermi GBM Detection
  16. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  17. Fermi GRB 260130A: Global MASTER-Net observations report
  18. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  19. GRB 260130A: Fermi GBM Final Real-time Localization
  20. Fermi GRB 260129A: Global MASTER-Net observations report
  21. GRB 260128B: LCO optical upper limits
  22. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  23. IPN triangulation of GRB 260121A
  24. GRB 260127A: Swift-BAT refined analysis
  25. GRB 260129B: Fermi GBM Final Localization
  26. GRB 260128B: SVOM detection of a burst through offline search
  27. GRB 260129A: Fermi GBM Final Localization
  28. IPN triangulation of GRB 260127B (short)
  29. GRB 260127B: Swift-XRT observations
  30. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  31. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  32. Fermi GRB 260127A: Global MASTER-Net observations report
  33. GRB 260127A: Fermi GBM Observation
  34. GRB 260127A: COLIBRÍ optical observations
  35. GRB 260127A: NOT optical observations
  36. GRB 260127B: Swift ToO observations
  37. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  38. GRB 260127A: Swift-XRT refined Analysis
  39. GRB 260127B: GOTO candidate optical counterpart
  40. GRB 260127A: SVOM/C-GFT optical observations
  41. GRB 260127A: Enhanced Swift-XRT position
  42. Fermi GRB 260127B: Global MASTER-Net observations report
  43. GRB 260127B: Fermi GBM Final Real-time Localization
  44. GRB 260127A: Prompt enhanced Swift-XRT position
  45. Swift GRB 260127A: Global MASTER-Net observations report
  46. GRB 260127A: LCO optical afterglow discovery
  47. GRB 260127A: Swift detection of a burst
  48. GRB 260127A: Fermi GBM Final Real-time Localization
  49. GRB 260125A: Swift-XRT observations
  50. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  51. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  52. Konus-Wind detection of GRB 260120B
  53. GRB 251222A: SVOM/ECLAIRs refined analysis
  54. GRB 260125A: Swift ToO observations
  55. GRB 260125A: GOTO candidate optical counterpart
  56. Fermi GRB 260125B: Global MASTER-Net observations report
  57. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  58. GRB 260125B: Fermi GBM Final Real-time Localization
  59. GRB 260125A: Fermi GBM Final Real-time Localization
  60. GRB 260114A: SVOM/VT optical upper limits
  61. GRB 260120A: AstroSat CZTI detection
  62. GRB 260122B: Swift-BAT refined analysis
  63. GRB 260120B: SVOM/GRM observation
  64. GRB 260120A: GECAM-B observation
  65. GRB 260120B: AstroSat CZTI detection
  66. GRB 260114A: Insight-HXMT/HE detection
  67. GRB 260122B: Swift detection of a burst
  68. EP260119a: Assy AZT-20 optical observations
  69. EP260119a: Mondy and SAO RAS optical upper limits
  70. GRB 260122A: Fermi GBM Final Real-time Localization
  71. Fermi GRB 260120C: Global MASTER-Net observations report
  72. GRB 260120B: Swift-BAT refined analysis
  73. GRB 260120B: Swift-XRT refined Analysis
  74. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  75. GRB 260120B: Fermi GBM Observation
  76. GRB 260120B: Swift/UVOT Detection
  77. GRB 260120B: COLIBRÍ optical upper limits
  78. GRB 260120B: Enhanced Swift-XRT position
  79. GRB 260120B: SVOM/C-GFT optical counterpart detection
  80. GRB 260120C: Fermi GBM Final Real-time Localization
  81. GRB 260101A: 239Alferov CubeSat detection
  82. GRB 260120B: Swift detection of a burst
  83. GRB 260120B: Fermi GBM Final Real-time Localization
  84. EP260119A: Mondy I-Band Observations
  85. Fermi trigger No 790601190: Global MASTER-Net observations report
  86. Fermi trigger No 790570272: Global MASTER-Net observations report
  87. GRB 260114A: Swift/UVOT Upper Limits
  88. GRB 251202A: further radio observations with the VLA
  89. EP260119a: KAIT optical observations
  90. GRB 260120A: Fermi GBM Final Real-time Localization
  91. EP260119a: SAO RAS optical observations
  92. GRB 251208D: SVOM/ECLAIRs refined analysis
  93. GRB 251208D: SVOM/ECLAIRs refined analysis
  94. GRB 260117A: Swift-XRT afterglow detection
  95. GRB 260115A: AstroSat CZTI detection
  96. GRB 260117A: ZTSh optical upper limit
  97. GRB 260110A: SVOM detection of a burst through offline search
  98. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  99. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  100. GRB 260117A: SVOM/VT optical candidate

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