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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"

26521 results found.

  1. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  2. GRB 260208A: SVOM/VT optical observation
  3. GRB 260208A: Swift-XRT observations
  4. GRB 260208B: SVOM/GRM observation of a bright burst
  5. GRB 260208B: Fermi GBM Detection
  6. GRB 260208B: Fermi-LAT detection
  7. GRB 260208A: Fermi-LAT detection
  8. GRB 260207B: GECAM-B observation
  9. GRB 260208A: Fermi GBM Classification Correction
  10. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  11. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  12. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  13. GRB 260131A/B: Mondy and Terskol optical observations
  14. GRB 260206A: Swift-XRT observations
  15. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  16. GRB 260204A: Swift-XRT observations
  17. GRB 260204A: LCO optical afterglow detection
  18. GRB 260204A: SVOM/VT optical candidate
  19. GRB 260204A : MASTER Global robotic net optical observations
  20. Fermi GBM Sub-Threshold Detection of GRB 260204A
  21. GRB 260204A: GOTO optical upper limit
  22. GRB 260204A: LCO optical upper limits
  23. EP260110a: Late GTC/EMIR near-infrared observations
  24. GRB 260204A: SVOM detection of a burst
  25. GRB 260121A: 239Alferov CubeSat detection
  26. Konus-Wind detection of GRB 260121A
  27. GRB 260131A/B: OHP/T193 optical observations
  28. GRB 251230A: MeerLICHT afterglow detection
  29. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  30. GRID detection of GRB 260131A/B
  31. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  32. GRB 260130A: Insight-HXMT/HE detection
  33. GRB 260130A: GECAM-B observation of a short burst
  34. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  35. GRB 260131A/B: EP/FXT X-ray afterglow detection
  36. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  37. GRB 260127B: Insight-HXMT/HE detection
  38. GRB 260127B: GECAM-B observation of a short burst
  39. GRB 260127A: GECAM-B observation
  40. EP260131a: Liverpool Telescope optical upper limits
  41. EP260131a: COLIBRÍ further observations
  42. Konus-Wind detection of GRB 260128A / EP260128a
  43. GRB 260131A: Insight-HXMT/HE detection
  44. Konus-Wind detection of GRB 260131A/B
  45. EP260131a: SVOM/VT optical observation
  46. EP260131a: Xinglong optical upper limit
  47. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  48. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  49. GRB 260131A/B: Fermi GBM Observation
  50. EP260131a: COLIBRÍ observations of slow optical fading
  51. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  52. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  53. EP260131a: COLIBRÍ optical observations of the counterpart
  54. GRB 260127B: AstroSat CZTI detection
  55. GRB 260130A: Fermi GBM Detection
  56. EP260131a: Einstein Probe detection of an X-ray transient
  57. GRB 260127B: Fermi GBM Detection
  58. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  59. GRB 260128B: LCO optical upper limits
  60. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  61. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  62. IPN triangulation of GRB 260121A
  63. GRB 260127A: Swift-BAT refined analysis
  64. GRB 260128B: SVOM detection of a burst through offline search
  65. IPN triangulation of GRB 260127B (short)
  66. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  67. EP260128a: NOT optical counterpart candidate
  68. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  69. EP260126a: SVOM/VT optical upperlimit
  70. EP260128a: Einstein Probe detection of an X-ray transient
  71. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  72. GRB 260127A: Fermi GBM Observation
  73. GRB 260127A: COLIBRÍ optical observations
  74. GRB 260127A: NOT optical observations
  75. EP260126a: Seimei/TriCCS optical upper limit
  76. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  77. GRB 260127B: GOTO candidate optical counterpart
  78. GRB 260127A: SVOM/C-GFT optical observations
  79. GRB 260127A: Enhanced Swift-XRT position
  80. GRB 260127A: Prompt enhanced Swift-XRT position
  81. GRB 260127A: LCO optical afterglow discovery
  82. GRB 260127A: Swift detection of a burst
  83. EP260126a: EP-FXT follow-up observation
  84. EP260126a: Optical upper limit with Kinder observations
  85. EP260126a: COLIBRÍ optical upper limits
  86. EP260126a: Einstein Probe detection of a fast X-ray transient
  87. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  88. Konus-Wind detection of GRB 260120B
  89. GRB 251222A: SVOM/ECLAIRs refined analysis
  90. GRB 260125A: GOTO candidate optical counterpart
  91. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 260114A: SVOM/VT optical upper limits
  93. GRB 260120A: AstroSat CZTI detection
  94. GRB 260122B: Swift-BAT refined analysis
  95. GRB 260120B: SVOM/GRM observation
  96. GRB 260120A: GECAM-B observation
  97. GRB 260120B: AstroSat CZTI detection
  98. GRB 260114A: Insight-HXMT/HE detection
  99. GRB 260122B: Swift detection of a burst
  100. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility

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