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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"

20357 results found.

  1. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  3. GRB 260706A: ATCA detection of possible radio counterpart
  4. GRB 260705A: ATCA radio observations
  5. EP260713a: Einstein Probe detection of an X-ray transient
  6. EP260623a: KAIT optical observations
  7. GRB 260708A: GRANDMA Optical Observations
  8. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  9. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 260708A: LCO optical observations
  11. EP260711a: Einstein Probe detection of an X-ray transient
  12. GRB 260709A: SVOM/GRM detection
  13. GRB 260709A: GECAM-B observation
  14. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  15. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  16. GRB 260704A: SVOM/ECLAIRs refined analysis
  17. GRB 260706A : GRANDMA Upper limits
  18. GRB 260708A: Kilonova-Catcher optical afterglow detection
  19. IceCube-260708A: One candidate from the Zwicky Transient Facility
  20. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  21. GRB 260705B: SVOM/GRM observation
  22. EP260707a (by EP-FXT): NOT optical upper limit
  23. EP260707a is not a real source
  24. EP260707a: LCOGT Optical Upper Limit
  25. EP260707a: TRT optical upper limit
  26. EP260707a: Einstein Probe detection of an X-ray transient
  27. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  28. GRB 260706A: SVOM/ECLAIRs refined analysis
  29. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  30. GRB 260706A: REM optical/NIR observations
  31. GRB 260706A: LCO optical upper limit
  32. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 260705A: SVOM/ECLAIRs refined analysis
  34. GRB 260705A: LCO optical upper limits
  35. GRB 260704A: NOT optical upper limits
  36. GRB 260629A: SVOM/GRM observation of a short burst
  37. GRB 260629A: AstroSat CZTI detection
  38. GRB 260704A: SVOM detection of a possible GRB
  39. EP260703a: EP-WXT detection of a fast X-ray transient
  40. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  41. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  42. EP260628a: EP-WXT detection of a fast X-ray transient
  43. EP260626a: further Liverpool Telescope optical upper limits
  44. EP260626a: COLIBRÍ optical upper limit
  45. EP260626a: Liverpool Telescope upper limits
  46. EP260626a: EP-WXT detection of a fast X-ray transient
  47. EP260623a: TNG NIR afterglow detection
  48. MASS-Cube (GRID 2.0) detection of GRB 260616B
  49. GRB 260619A: SVOM/ECLAIRs refined analysis
  50. EP260623a: Liverpool Telescope optical observations
  51. Konus-Wind detection of GRB 260618B
  52. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  53. EP260623a: WINTER J-band observations
  54. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  55. EP260623a: Optical follow-up observations with Kinder
  56. EP260623a: SVOM/VT optical observations
  57. EP260623a: TRT optical observations
  58. EP260623a: REM optical/NIR afterglow detection
  59. EP 260623a: COLIBRÍ optical observations
  60. EP260623a: Las Cumbres discovery of the optical counterpart
  61. EP260623a: Einstein Probe detection of an X-ray transient
  62. GRB 260614B: EP-FXT follow-up observation
  63. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  64. EP260618a: Liverpool Telescope optical observations
  65. GRB 260618B: LCO optical observations
  66. EP260618a: JinShan optical observations
  67. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  68. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 260619A: TRT optical counterpart confirmation
  70. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  71. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  72. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  73. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  74. Konus-Wind detection of GRB 260617A
  75. GRB 260616A: AstroSat CZTI detection
  76. GRB 260616A: SVOM/GRM observation
  77. EP260618a: OHP/T193 optical observations
  78. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  79. GRB 260619A: Kilonova-Catcher optical upper limit
  80. EP260618a: LCO optical counterpart confirmation
  81. EP260618a: COLIBRÍ optical counterpart candidate
  82. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  83. EP260618a: EP-WXT detection of an X-ray transient
  84. GRB 260610B: AbAO optical observations
  85. GRB 260616C: GECAM-B observation of a burst
  86. Konus-Wind detection of GRB 260616A
  87. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  88. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  89. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  90. EP260616a: EP-WXT detection of a fast X-ray transient
  91. GRB 260614B: SVOM/ECLAIRs refined analysis
  92. GRB 260610B: Terskol optical observations
  93. GRB 260610B: SVOM/GRM observation
  94. GRB 260614B: SVOM/VT optical candidate from VHF data
  95. GRB 260614B: SVOM detection of a burst
  96. GRB 260611B: SVOM/GRM detection
  97. GRB 260603C: AstroSat CZTI detection
  98. GRB 260610B: further Liverpool Telescope optical observations
  99. GRB 260610B / AT2026owq: GRANDMA optical observations
  100. GRB 260610B / AT2026owq: further SAO RAS optical observations

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