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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

20359 results found.

  1. GRB 260714B: SVOM/GRM observation
  2. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  3. GRB 260714B: GECAM-B observation of a burst
  4. GRB 260714B: COLIBRÍ optical counterpart candidate
  5. sb26071506: SVOM detection of a X-ray transient
  6. EP260703a: SVOM/ECLAIRs Upper Limit
  7. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  8. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  9. GRB 260706A: ATCA detection of possible radio counterpart
  10. GRB 260705A: ATCA radio observations
  11. EP260713a: Einstein Probe detection of an X-ray transient
  12. EP260623a: KAIT optical observations
  13. GRB 260708A: GRANDMA Optical Observations
  14. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  15. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 260708A: LCO optical observations
  17. EP260711a: Einstein Probe detection of an X-ray transient
  18. GRB 260709A: SVOM/GRM detection
  19. GRB 260709A: GECAM-B observation
  20. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  21. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  22. GRB 260704A: SVOM/ECLAIRs refined analysis
  23. GRB 260706A : GRANDMA Upper limits
  24. GRB 260708A: Kilonova-Catcher optical afterglow detection
  25. IceCube-260708A: One candidate from the Zwicky Transient Facility
  26. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  27. GRB 260705B: SVOM/GRM observation
  28. EP260707a (by EP-FXT): NOT optical upper limit
  29. EP260707a is not a real source
  30. EP260707a: LCOGT Optical Upper Limit
  31. EP260707a: TRT optical upper limit
  32. EP260707a: Einstein Probe detection of an X-ray transient
  33. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  34. GRB 260706A: SVOM/ECLAIRs refined analysis
  35. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  36. GRB 260706A: REM optical/NIR observations
  37. GRB 260706A: LCO optical upper limit
  38. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 260705A: SVOM/ECLAIRs refined analysis
  40. GRB 260705A: LCO optical upper limits
  41. GRB 260704A: NOT optical upper limits
  42. GRB 260629A: SVOM/GRM observation of a short burst
  43. GRB 260629A: AstroSat CZTI detection
  44. GRB 260704A: SVOM detection of a possible GRB
  45. EP260703a: EP-WXT detection of a fast X-ray transient
  46. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  47. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  48. EP260628a: EP-WXT detection of a fast X-ray transient
  49. EP260626a: further Liverpool Telescope optical upper limits
  50. EP260626a: COLIBRÍ optical upper limit
  51. EP260626a: Liverpool Telescope upper limits
  52. EP260626a: EP-WXT detection of a fast X-ray transient
  53. EP260623a: TNG NIR afterglow detection
  54. MASS-Cube (GRID 2.0) detection of GRB 260616B
  55. GRB 260619A: SVOM/ECLAIRs refined analysis
  56. EP260623a: Liverpool Telescope optical observations
  57. Konus-Wind detection of GRB 260618B
  58. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  59. EP260623a: WINTER J-band observations
  60. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  61. EP260623a: Optical follow-up observations with Kinder
  62. EP260623a: SVOM/VT optical observations
  63. EP260623a: TRT optical observations
  64. EP260623a: REM optical/NIR afterglow detection
  65. EP 260623a: COLIBRÍ optical observations
  66. EP260623a: Las Cumbres discovery of the optical counterpart
  67. EP260623a: Einstein Probe detection of an X-ray transient
  68. GRB 260614B: EP-FXT follow-up observation
  69. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  70. EP260618a: Liverpool Telescope optical observations
  71. GRB 260618B: LCO optical observations
  72. EP260618a: JinShan optical observations
  73. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  74. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  75. GRB 260619A: TRT optical counterpart confirmation
  76. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  77. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  78. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  79. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. Konus-Wind detection of GRB 260617A
  81. GRB 260616A: AstroSat CZTI detection
  82. GRB 260616A: SVOM/GRM observation
  83. EP260618a: OHP/T193 optical observations
  84. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  85. GRB 260619A: Kilonova-Catcher optical upper limit
  86. EP260618a: LCO optical counterpart confirmation
  87. EP260618a: COLIBRÍ optical counterpart candidate
  88. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  89. EP260618a: EP-WXT detection of an X-ray transient
  90. GRB 260610B: AbAO optical observations
  91. GRB 260616C: GECAM-B observation of a burst
  92. Konus-Wind detection of GRB 260616A
  93. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  94. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  95. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  96. EP260616a: EP-WXT detection of a fast X-ray transient
  97. GRB 260614B: SVOM/ECLAIRs refined analysis
  98. GRB 260610B: Terskol optical observations
  99. GRB 260610B: SVOM/GRM observation
  100. GRB 260614B: SVOM/VT optical candidate from VHF data

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