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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"

37159 results found.

  1. GRB 260130A: GECAM-B observation of a short burst
  2. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  3. GRB 260131A/B: EP/FXT X-ray afterglow detection
  4. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  5. GRB 260127B: Insight-HXMT/HE detection
  6. GRB 260127B: GECAM-B observation of a short burst
  7. GRB 260127A: GECAM-B observation
  8. GRB 260131A: NOT spectroscopic redshift z = 1.434
  9. EP260131a: Liverpool Telescope optical upper limits
  10. Konus-Wind detection of GRB 260128A / EP260128a
  11. GRB 260131A: Insight-HXMT/HE detection
  12. Konus-Wind detection of GRB 260131A/B
  13. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  14. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  15. GRB 260131A/B: Fermi GBM Observation
  16. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  17. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  18. GRB 260131B: MAXI/GSC detection
  19. GRB 260131A: Fermi GBM Final Real-time Localization
  20. GRB 260127B: AstroSat CZTI detection
  21. GRB 260130A: Fermi GBM Detection
  22. GRB 260127B: Fermi GBM Detection
  23. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  24. Fermi GRB 260130A: Global MASTER-Net observations report
  25. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  26. GRB 260130A: Fermi GBM Final Real-time Localization
  27. Fermi GRB 260129A: Global MASTER-Net observations report
  28. GRB 260128B: LCO optical upper limits
  29. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  30. IPN triangulation of GRB 260121A
  31. GRB 260127A: Swift-BAT refined analysis
  32. GRB 260129B: Fermi GBM Final Localization
  33. GRB 260128B: SVOM detection of a burst through offline search
  34. GRB 260129A: Fermi GBM Final Localization
  35. IPN triangulation of GRB 260127B (short)
  36. GRB 260127B: Swift-XRT observations
  37. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  38. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  39. Fermi GRB 260127A: Global MASTER-Net observations report
  40. GRB 260127A: Fermi GBM Observation
  41. GRB 260127A: COLIBRÍ optical observations
  42. GRB 260127A: NOT optical observations
  43. GRB 260127B: Swift ToO observations
  44. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  45. GRB 260127A: Swift-XRT refined Analysis
  46. GRB 260127B: GOTO candidate optical counterpart
  47. GRB 260127A: SVOM/C-GFT optical observations
  48. GRB 260127A: Enhanced Swift-XRT position
  49. Fermi GRB 260127B: Global MASTER-Net observations report
  50. GRB 260127B: Fermi GBM Final Real-time Localization
  51. GRB 260127A: Prompt enhanced Swift-XRT position
  52. Swift GRB 260127A: Global MASTER-Net observations report
  53. GRB 260127A: LCO optical afterglow discovery
  54. GRB 260127A: Swift detection of a burst
  55. GRB 260127A: Fermi GBM Final Real-time Localization
  56. GRB 260125A: Swift-XRT observations
  57. EP260126a: Optical upper limit with Kinder observations
  58. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  59. Konus-Wind detection of GRB 260120B
  60. GRB 251222A: SVOM/ECLAIRs refined analysis
  61. GRB 260125A: Swift ToO observations
  62. GRB 260125A: GOTO candidate optical counterpart
  63. Fermi GRB 260125B: Global MASTER-Net observations report
  64. GRB 260125B: Fermi GBM Final Real-time Localization
  65. GRB 260125A: Fermi GBM Final Real-time Localization
  66. GRB 260114A: SVOM/VT optical upper limits
  67. GRB 260120A: AstroSat CZTI detection
  68. GRB 260122B: Swift-BAT refined analysis
  69. GRB 260120B: SVOM/GRM observation
  70. GRB 260120A: GECAM-B observation
  71. GRB 260120B: AstroSat CZTI detection
  72. GRB 260114A: Insight-HXMT/HE detection
  73. GRB 260122B: Swift detection of a burst
  74. EP260119a: Assy AZT-20 optical observations
  75. EP260119a: Mondy and SAO RAS optical upper limits
  76. GRB 260122A: Fermi GBM Final Real-time Localization
  77. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  78. Fermi GRB 260120C: Global MASTER-Net observations report
  79. GRB 260120B: Swift-BAT refined analysis
  80. GRB 260120B: Swift-XRT refined Analysis
  81. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  82. GRB 260120B: Fermi GBM Observation
  83. GRB 260120B: Swift/UVOT Detection
  84. GRB 260120B: COLIBRÍ optical upper limits
  85. GRB 260120B: Enhanced Swift-XRT position
  86. GRB 260120B: SVOM/C-GFT optical counterpart detection
  87. GRB 260120C: Fermi GBM Final Real-time Localization
  88. GRB 260101A: 239Alferov CubeSat detection
  89. GRB 260120B: Swift detection of a burst
  90. GRB 260120B: Fermi GBM Final Real-time Localization
  91. EP260119A: Mondy I-Band Observations
  92. GRB 260114A: Swift/UVOT Upper Limits
  93. EP260119a: Liverpool Telescope optical follow-up observations
  94. GRB 251202A: further radio observations with the VLA
  95. EP260119a: KAIT optical observations
  96. GRB 260120A: Fermi GBM Final Real-time Localization
  97. EP260119a: SAO RAS optical observations
  98. EP260116a: COLIBRÍ detection of a fading optical source
  99. GRB 251208D: SVOM/ECLAIRs refined analysis
  100. GRB 251208D: SVOM/ECLAIRs refined analysis

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