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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"

20361 results found.

  1. GRB 260714B: GECAM-B observation of a burst
  2. GRB 260714B: COLIBRÍ optical counterpart candidate
  3. sb26071506: SVOM detection of a X-ray transient
  4. EP260703a: SVOM/ECLAIRs Upper Limit
  5. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  7. GRB 260706A: ATCA detection of possible radio counterpart
  8. GRB 260705A: ATCA radio observations
  9. EP260713a: Einstein Probe detection of an X-ray transient
  10. EP260623a: KAIT optical observations
  11. GRB 260708A: GRANDMA Optical Observations
  12. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  13. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 260708A: LCO optical observations
  15. EP260711a: Einstein Probe detection of an X-ray transient
  16. GRB 260709A: SVOM/GRM detection
  17. GRB 260709A: GECAM-B observation
  18. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  19. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  20. GRB 260704A: SVOM/ECLAIRs refined analysis
  21. GRB 260706A : GRANDMA Upper limits
  22. GRB 260708A: Kilonova-Catcher optical afterglow detection
  23. IceCube-260708A: One candidate from the Zwicky Transient Facility
  24. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  25. GRB 260705B: SVOM/GRM observation
  26. EP260707a (by EP-FXT): NOT optical upper limit
  27. EP260707a is not a real source
  28. EP260707a: LCOGT Optical Upper Limit
  29. EP260707a: TRT optical upper limit
  30. EP260707a: Einstein Probe detection of an X-ray transient
  31. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  32. GRB 260706A: SVOM/ECLAIRs refined analysis
  33. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  34. GRB 260706A: REM optical/NIR observations
  35. GRB 260706A: LCO optical upper limit
  36. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 260705A: SVOM/ECLAIRs refined analysis
  38. GRB 260705A: LCO optical upper limits
  39. GRB 260704A: NOT optical upper limits
  40. GRB 260629A: SVOM/GRM observation of a short burst
  41. GRB 260629A: AstroSat CZTI detection
  42. GRB 260704A: SVOM detection of a possible GRB
  43. EP260703a: EP-WXT detection of a fast X-ray transient
  44. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  45. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  46. EP260628a: EP-WXT detection of a fast X-ray transient
  47. EP260626a: further Liverpool Telescope optical upper limits
  48. EP260626a: COLIBRÍ optical upper limit
  49. EP260626a: Liverpool Telescope upper limits
  50. EP260626a: EP-WXT detection of a fast X-ray transient
  51. EP260623a: TNG NIR afterglow detection
  52. MASS-Cube (GRID 2.0) detection of GRB 260616B
  53. GRB 260619A: SVOM/ECLAIRs refined analysis
  54. EP260623a: Liverpool Telescope optical observations
  55. Konus-Wind detection of GRB 260618B
  56. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  57. EP260623a: WINTER J-band observations
  58. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  59. EP260623a: Optical follow-up observations with Kinder
  60. EP260623a: SVOM/VT optical observations
  61. EP260623a: TRT optical observations
  62. EP260623a: REM optical/NIR afterglow detection
  63. EP 260623a: COLIBRÍ optical observations
  64. EP260623a: Las Cumbres discovery of the optical counterpart
  65. EP260623a: Einstein Probe detection of an X-ray transient
  66. GRB 260614B: EP-FXT follow-up observation
  67. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  68. EP260618a: Liverpool Telescope optical observations
  69. GRB 260618B: LCO optical observations
  70. EP260618a: JinShan optical observations
  71. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  72. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 260619A: TRT optical counterpart confirmation
  74. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  75. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  76. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  77. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  78. Konus-Wind detection of GRB 260617A
  79. GRB 260616A: AstroSat CZTI detection
  80. GRB 260616A: SVOM/GRM observation
  81. EP260618a: OHP/T193 optical observations
  82. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  83. GRB 260619A: Kilonova-Catcher optical upper limit
  84. EP260618a: LCO optical counterpart confirmation
  85. EP260618a: COLIBRÍ optical counterpart candidate
  86. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  87. EP260618a: EP-WXT detection of an X-ray transient
  88. GRB 260610B: AbAO optical observations
  89. GRB 260616C: GECAM-B observation of a burst
  90. Konus-Wind detection of GRB 260616A
  91. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  92. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  93. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  94. EP260616a: EP-WXT detection of a fast X-ray transient
  95. GRB 260614B: SVOM/ECLAIRs refined analysis
  96. GRB 260610B: Terskol optical observations
  97. GRB 260610B: SVOM/GRM observation
  98. GRB 260614B: SVOM/VT optical candidate from VHF data
  99. GRB 260614B: SVOM detection of a burst
  100. GRB 260611B: SVOM/GRM detection

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