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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"

20351 results found.

  1. GRB 260706A: ATCA detection of possible radio counterpart
  2. GRB 260705A: ATCA radio observations
  3. EP260713a: Einstein Probe detection of an X-ray transient
  4. EP260623a: KAIT optical observations
  5. GRB 260708A: GRANDMA Optical Observations
  6. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  7. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 260708A: LCO optical observations
  9. EP260711a: Einstein Probe detection of an X-ray transient
  10. GRB 260709A: SVOM/GRM detection
  11. GRB 260709A: GECAM-B observation
  12. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  13. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  14. GRB 260704A: SVOM/ECLAIRs refined analysis
  15. GRB 260706A : GRANDMA Upper limits
  16. GRB 260708A: Kilonova-Catcher optical afterglow detection
  17. IceCube-260708A: One candidate from the Zwicky Transient Facility
  18. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  19. GRB 260705B: SVOM/GRM observation
  20. EP260707a (by EP-FXT): NOT optical upper limit
  21. EP260707a is not a real source
  22. EP260707a: LCOGT Optical Upper Limit
  23. EP260707a: TRT optical upper limit
  24. EP260707a: Einstein Probe detection of an X-ray transient
  25. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  26. GRB 260706A: SVOM/ECLAIRs refined analysis
  27. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  28. GRB 260706A: REM optical/NIR observations
  29. GRB 260706A: LCO optical upper limit
  30. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 260705A: SVOM/ECLAIRs refined analysis
  32. GRB 260705A: LCO optical upper limits
  33. GRB 260704A: NOT optical upper limits
  34. GRB 260629A: SVOM/GRM observation of a short burst
  35. GRB 260629A: AstroSat CZTI detection
  36. GRB 260704A: SVOM detection of a possible GRB
  37. EP260703a: EP-WXT detection of a fast X-ray transient
  38. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  39. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  40. EP260628a: EP-WXT detection of a fast X-ray transient
  41. EP260626a: further Liverpool Telescope optical upper limits
  42. EP260626a: COLIBRÍ optical upper limit
  43. EP260626a: Liverpool Telescope upper limits
  44. EP260626a: EP-WXT detection of a fast X-ray transient
  45. EP260623a: TNG NIR afterglow detection
  46. MASS-Cube (GRID 2.0) detection of GRB 260616B
  47. GRB 260619A: SVOM/ECLAIRs refined analysis
  48. EP260623a: Liverpool Telescope optical observations
  49. Konus-Wind detection of GRB 260618B
  50. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  51. EP260623a: WINTER J-band observations
  52. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  53. EP260623a: Optical follow-up observations with Kinder
  54. EP260623a: SVOM/VT optical observations
  55. EP260623a: TRT optical observations
  56. EP260623a: REM optical/NIR afterglow detection
  57. EP 260623a: COLIBRÍ optical observations
  58. EP260623a: Las Cumbres discovery of the optical counterpart
  59. EP260623a: Einstein Probe detection of an X-ray transient
  60. GRB 260614B: EP-FXT follow-up observation
  61. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  62. EP260618a: Liverpool Telescope optical observations
  63. GRB 260618B: LCO optical observations
  64. EP260618a: JinShan optical observations
  65. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  66. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 260619A: TRT optical counterpart confirmation
  68. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  69. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  70. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  71. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  72. Konus-Wind detection of GRB 260617A
  73. GRB 260616A: AstroSat CZTI detection
  74. GRB 260616A: SVOM/GRM observation
  75. EP260618a: OHP/T193 optical observations
  76. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  77. GRB 260619A: Kilonova-Catcher optical upper limit
  78. EP260618a: LCO optical counterpart confirmation
  79. EP260618a: COLIBRÍ optical counterpart candidate
  80. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  81. EP260618a: EP-WXT detection of an X-ray transient
  82. GRB 260610B: AbAO optical observations
  83. GRB 260616C: GECAM-B observation of a burst
  84. Konus-Wind detection of GRB 260616A
  85. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  86. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  87. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  88. EP260616a: EP-WXT detection of a fast X-ray transient
  89. GRB 260614B: SVOM/ECLAIRs refined analysis
  90. GRB 260610B: Terskol optical observations
  91. GRB 260610B: SVOM/GRM observation
  92. GRB 260614B: SVOM/VT optical candidate from VHF data
  93. GRB 260614B: SVOM detection of a burst
  94. GRB 260611B: SVOM/GRM detection
  95. GRB 260603C: AstroSat CZTI detection
  96. GRB 260610B: further Liverpool Telescope optical observations
  97. GRB 260610B / AT2026owq: GRANDMA optical observations
  98. GRB 260610B / AT2026owq: further SAO RAS optical observations
  99. EP260605a: COLIBRÍ optical upper limits
  100. GRB 260610b: Liverpool Telescope optical observations

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