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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"

23700 results found.

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

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