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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"

20358 results found.

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

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