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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"

23699 results found.

  1. GRB 260127A: GECAM-B observation
  2. EP260131a: COLIBRÍ further observations
  3. Konus-Wind detection of GRB 260128A / EP260128a
  4. Konus-Wind detection of GRB 260131A/B
  5. EP260131a: Xinglong optical upper limit
  6. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  7. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  8. EP260131a: COLIBRÍ observations of slow optical fading
  9. GRB 260131B: MAXI/GSC detection
  10. EP260131a: COLIBRÍ optical observations of the counterpart
  11. GRB 260127B: AstroSat CZTI detection
  12. GRB 260130A: Fermi GBM Detection
  13. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  14. Fermi GRB 260130A: Global MASTER-Net observations report
  15. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  16. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  17. IPN triangulation of GRB 260121A
  18. GRB 260127A: Swift-BAT refined analysis
  19. GRB 260128B: SVOM detection of a burst through offline search
  20. IPN triangulation of GRB 260127B (short)
  21. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  22. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  23. EP260128a: NOT optical counterpart candidate
  24. GRB 260127A: COLIBRÍ optical observations
  25. EP260126a: Seimei/TriCCS optical upper limit
  26. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  27. GRB 260127B: GOTO candidate optical counterpart
  28. GRB 260127A: LCO optical afterglow discovery
  29. GRB 260127A: Swift detection of a burst
  30. EP260126a: Optical upper limit with Kinder observations
  31. EP260126a: COLIBRÍ optical upper limits
  32. EP260126a: NOT optical observations
  33. Konus-Wind detection of GRB 260120B
  34. GRB 260125A: GOTO candidate optical counterpart
  35. GRB 260114A: SVOM/VT optical upper limits
  36. GRB 260120A: AstroSat CZTI detection
  37. GRB 260122B: Swift-BAT refined analysis
  38. GRB 260120B: AstroSat CZTI detection
  39. GRB 260122B: Swift detection of a burst
  40. EP260119a: Assy AZT-20 optical observations
  41. EP260119a: Xinglong optical upper limit
  42. GRB 260120B: Swift-BAT refined analysis
  43. GRB 260120B: Swift-XRT refined Analysis
  44. EP260116a: COLIBRÍ further observations
  45. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  46. GRB 260120B: Swift/UVOT Detection
  47. GRB 260120B: COLIBRÍ optical upper limits
  48. GRB 260101A: 239Alferov CubeSat detection
  49. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  50. GRB 260120B: Swift detection of a burst
  51. GRB 251202A: further radio observations with the VLA
  52. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  53. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  54. EP260119a: KAIT optical observations
  55. EP260119a: NOT optical observations
  56. EP260116a: COLIBRÍ detection of a fading optical source
  57. GRB 251208D: SVOM/ECLAIRs refined analysis
  58. GRB 251208D: SVOM/ECLAIRs refined analysis
  59. GRB 260117A: Swift-XRT afterglow detection
  60. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  61. GRB 260115A: AstroSat CZTI detection
  62. EP260119a: COLIBRÍ optical counterpart candidate
  63. GRB 260110A: SVOM detection of a burst through offline search
  64. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  65. Swift trigger on the HMXB 1A 1118-61
  66. GRB 260117A: Swift-XRT observations
  67. EP 260116a: COLIBRÍ optical upper limit
  68. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  69. GRB 260114A: VLT/MUSE spectroscopic observations
  70. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  71. EP260116a: Xinglong optical upper limit
  72. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  73. GRB260114A: STEP/T80S optical limits
  74. GRB 251222A: radio detection with the VLA
  75. Konus-Wind detection of GRB 260114A
  76. GRB 260114A: Swift-XRT refined Analysis
  77. GRB 260114A: 6 GHz VLA observations
  78. GRB 260114A : MITSuME Akeno optical upper limits
  79. GRB 260114A: COLIBRÍ optical upper limits
  80. GRB 260114A: TNG NIR upper limit
  81. Konus-Wind detection of GRB 251230A / EP251230a
  82. GRB 260114A: Swift detection of a short burst
  83. EP260110a: TRT optical upper limits
  84. Konus-Wind detection of GRB 260101A
  85. GRB 260111A: Swift-XRT observations
  86. Swift Trigger 1439093: is probably not GRB 260113A
  87. GRB 260111A: COLIBRÍ optical afterglow candidate
  88. Swift Trigger 1434591 is not a GRB
  89. GRB 260111A: GOTO optical upper limits
  90. IceCube Alert 260111A: Global MASTER-Net observations report
  91. Swift trigger 1436759 is not an astrophysical event
  92. EP260110a: KAIT optical upper limit
  93. EP 260110a: COLIBRÍ optical observations
  94. EP260110a: BOOTES-5/JGU optical upper limit
  95. GRB 260109C: Kilonova-Catcher optical upper limit
  96. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  97. Swift Trigger 1434591: possible GRB 260109C
  98. GRB 260102A: Swift-XRT afterglow detection
  99. GRB 260104A: Swift-BAT refined analysis
  100. GRB 260101A: Swift-BAT refined analysis

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