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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"

45543 results found.

  1. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  2. IPN triangulation of GRB 260121A
  3. GRB 260127A: Swift-BAT refined analysis
  4. GRB 260129B: Fermi GBM Final Localization
  5. GRB 260128B: SVOM detection of a burst through offline search
  6. GRB 260129A: Fermi GBM Final Localization
  7. IPN triangulation of GRB 260127B (short)
  8. GRB 260127B: Swift-XRT observations
  9. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  10. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  11. EP260128a: NOT optical counterpart candidate
  12. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  13. EP260128a: Liverpool Telescope optical observations and possible counterpart
  14. EP260128a: LCO optical upper limits
  15. EP260126a: SVOM/VT optical upperlimit
  16. EP260128a: Global MASTER-Net observations report
  17. EP260128a: Einstein Probe detection of an X-ray transient
  18. Fermi GRB 260127A: Global MASTER-Net observations report
  19. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  20. GRB 260127A: Fermi GBM Observation
  21. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 260127A: COLIBRÍ optical observations
  23. GRB 260127A: NOT optical observations
  24. GRB 260127B: Swift ToO observations
  25. EP260126a: Seimei/TriCCS optical upper limit
  26. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  27. GRB 260127A: Swift-XRT refined Analysis
  28. GRB 260127B: GOTO candidate optical counterpart
  29. GRB 260127A: SVOM/C-GFT optical observations
  30. The EP-WXT trigger 01709253145 is likely a flaring star
  31. GRB 260127A: Enhanced Swift-XRT position
  32. Fermi GRB 260127B: Global MASTER-Net observations report
  33. GRB 260127B: Fermi GBM Final Real-time Localization
  34. GRB 260127A: Prompt enhanced Swift-XRT position
  35. Swift GRB 260127A: Global MASTER-Net observations report
  36. GRB 260127A: LCO optical afterglow discovery
  37. GRB 260127A: Swift detection of a burst
  38. GRB 260127A: Fermi GBM Final Real-time Localization
  39. GRB 260125A: Swift-XRT observations
  40. EP260126a: EP-FXT follow-up observation
  41. EP260126a: Optical upper limit with Kinder observations
  42. EP260126a: Liverpool Telescope optical upper limits
  43. EP260126a: Further NOT optical upper limits
  44. EP260126a: COLIBRÍ optical upper limits
  45. EP260126a: NOT optical observations
  46. EP260126a: Einstein Probe detection of a fast X-ray transient
  47. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  48. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  49. Konus-Wind detection of GRB 260120B
  50. GRB 251222A: SVOM/ECLAIRs refined analysis
  51. GRB 260125A: Swift ToO observations
  52. GRB 260125A: GOTO candidate optical counterpart
  53. Fermi GRB 260125B: Global MASTER-Net observations report
  54. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 260125B: Fermi GBM Final Real-time Localization
  56. GRB 260125A: Fermi GBM Final Real-time Localization
  57. GRB 260114A: SVOM/VT optical upper limits
  58. GRB 260120A: AstroSat CZTI detection
  59. GRB 260122B: Swift-BAT refined analysis
  60. GRB 260120B: SVOM/GRM observation
  61. GRB 260120A: GECAM-B observation
  62. GRB 260120B: AstroSat CZTI detection
  63. GRB 260114A: Insight-HXMT/HE detection
  64. GRB 260122B: Swift detection of a burst
  65. Swift GRB260122.97: Global MASTER-Net observations report
  66. EP260119a: Assy AZT-20 optical observations
  67. EP260119a: Mondy and SAO RAS optical upper limits
  68. GRB 260122A: Fermi GBM Final Real-time Localization
  69. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  70. EP260119a: Xinglong optical upper limit
  71. The EP-WXT trigger 01709251871 is likely a flaring star
  72. Fermi GRB 260120C: Global MASTER-Net observations report
  73. GRB 260120B: Swift-BAT refined analysis
  74. GRB 260120B: Swift-XRT refined Analysis
  75. EP260116a: COLIBRÍ further observations
  76. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  77. GRB 260120B: Fermi GBM Observation
  78. EP260105a: GTC/HiPERCAM optical observations
  79. GRB 260120B: Swift/UVOT Detection
  80. GRB 260120B: COLIBRÍ optical upper limits
  81. SVOM GRB260121.06: Global MASTER-Net observations report
  82. GRB 260120B: Enhanced Swift-XRT position
  83. GRB 260120B: SVOM/C-GFT optical counterpart detection
  84. GRB 260120C: Fermi GBM Final Real-time Localization
  85. GRB 260101A: 239Alferov CubeSat detection
  86. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  87. GRB 260120B: Swift detection of a burst
  88. Swift GRB260120B: Global MASTER-Net observations report
  89. GRB 260120B: Fermi GBM Final Real-time Localization
  90. EP260119A: Mondy I-Band Observations
  91. Fermi trigger No 790601190: Global MASTER-Net observations report
  92. Fermi trigger No 790570272: Global MASTER-Net observations report
  93. GRB 260114A: Swift/UVOT Upper Limits
  94. EP260119a: Liverpool Telescope optical follow-up observations
  95. GRB 251202A: further radio observations with the VLA
  96. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  97. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  98. EP260119a: KAIT optical observations
  99. GRB 260120A: Fermi GBM Final Real-time Localization
  100. EP260119a: SVOM/VT optical observation

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