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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"

36341 results found.

  1. GRB 260121A: 239Alferov CubeSat detection
  2. Konus-Wind detection of GRB 260121A
  3. GRB 260131A/B: OHP/T193 optical observations
  4. GRB 260131A: KAIT optical observations
  5. GRB 251230A: MeerLICHT afterglow detection
  6. GRB 260131A: FTW optical and NIR observations
  7. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  8. GRID detection of GRB 260131A/B
  9. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  10. GRB 260130A: Insight-HXMT/HE detection
  11. GRB 260130A: GECAM-B observation of a short burst
  12. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  13. GRB 260131A/B: EP/FXT X-ray afterglow detection
  14. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  15. GRB 260127B: Insight-HXMT/HE detection
  16. GRB 260127B: GECAM-B observation of a short burst
  17. GRB 260127A: GECAM-B observation
  18. GRB 260131A: NOT spectroscopic redshift z = 1.434
  19. Konus-Wind detection of GRB 260128A / EP260128a
  20. GRB 260131A: Insight-HXMT/HE detection
  21. Konus-Wind detection of GRB 260131A/B
  22. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  23. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  24. GRB 260131A/B: Fermi GBM Observation
  25. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  26. GRB 260131B: MAXI/GSC detection
  27. GRB 260131A: Fermi GBM Final Real-time Localization
  28. GRB 260127B: AstroSat CZTI detection
  29. GRB 260130A: Fermi GBM Detection
  30. GRB 260127B: Fermi GBM Detection
  31. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  32. Fermi GRB 260130A: Global MASTER-Net observations report
  33. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  34. GRB 260130A: Fermi GBM Final Real-time Localization
  35. Fermi GRB 260129A: Global MASTER-Net observations report
  36. GRB 260128B: LCO optical upper limits
  37. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  38. IPN triangulation of GRB 260121A
  39. GRB 260127A: Swift-BAT refined analysis
  40. GRB 260129B: Fermi GBM Final Localization
  41. GRB 260128B: SVOM detection of a burst through offline search
  42. GRB 260129A: Fermi GBM Final Localization
  43. IPN triangulation of GRB 260127B (short)
  44. GRB 260127B: Swift-XRT observations
  45. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  46. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  47. Fermi GRB 260127A: Global MASTER-Net observations report
  48. GRB 260127A: Fermi GBM Observation
  49. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  50. GRB 260127A: COLIBRÍ optical observations
  51. GRB 260127A: NOT optical observations
  52. GRB 260127B: Swift ToO observations
  53. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  54. GRB 260127A: Swift-XRT refined Analysis
  55. GRB 260127B: GOTO candidate optical counterpart
  56. GRB 260127A: SVOM/C-GFT optical observations
  57. GRB 260127A: Enhanced Swift-XRT position
  58. Fermi GRB 260127B: Global MASTER-Net observations report
  59. GRB 260127B: Fermi GBM Final Real-time Localization
  60. GRB 260127A: Prompt enhanced Swift-XRT position
  61. Swift GRB 260127A: Global MASTER-Net observations report
  62. GRB 260127A: LCO optical afterglow discovery
  63. GRB 260127A: Swift detection of a burst
  64. GRB 260127A: Fermi GBM Final Real-time Localization
  65. GRB 260125A: Swift-XRT observations
  66. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  67. Konus-Wind detection of GRB 260120B
  68. GRB 251222A: SVOM/ECLAIRs refined analysis
  69. GRB 260125A: Swift ToO observations
  70. GRB 260125A: GOTO candidate optical counterpart
  71. Fermi GRB 260125B: Global MASTER-Net observations report
  72. GRB 260125B: Fermi GBM Final Real-time Localization
  73. GRB 260125A: Fermi GBM Final Real-time Localization
  74. GRB 260114A: SVOM/VT optical upper limits
  75. GRB 260120A: AstroSat CZTI detection
  76. GRB 260122B: Swift-BAT refined analysis
  77. GRB 260120B: SVOM/GRM observation
  78. GRB 260120A: GECAM-B observation
  79. GRB 260120B: AstroSat CZTI detection
  80. GRB 260114A: Insight-HXMT/HE detection
  81. GRB 260122B: Swift detection of a burst
  82. EP260119a: Assy AZT-20 optical observations
  83. EP260119a: Mondy and SAO RAS optical upper limits
  84. GRB 260122A: Fermi GBM Final Real-time Localization
  85. Fermi GRB 260120C: Global MASTER-Net observations report
  86. GRB 260120B: Swift-BAT refined analysis
  87. GRB 260120B: Swift-XRT refined Analysis
  88. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  89. GRB 260120B: Fermi GBM Observation
  90. GRB 260120B: Swift/UVOT Detection
  91. GRB 260120B: COLIBRÍ optical upper limits
  92. GRB 260120B: Enhanced Swift-XRT position
  93. GRB 260120B: SVOM/C-GFT optical counterpart detection
  94. GRB 260120C: Fermi GBM Final Real-time Localization
  95. GRB 260101A: 239Alferov CubeSat detection
  96. GRB 260120B: Swift detection of a burst
  97. GRB 260120B: Fermi GBM Final Real-time Localization
  98. EP260119A: Mondy I-Band Observations
  99. GRB 260114A: Swift/UVOT Upper Limits
  100. GRB 251202A: further radio observations with the VLA

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