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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"

23406 results found.

  1. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  2. GRB 260714B: COLIBRÍ optical counterpart candidate
  3. sb26071506: SVOM detection of a X-ray transient
  4. EP260703a: SVOM/ECLAIRs Upper Limit
  5. GRB 260709A: AstroSat CZTI detection
  6. GRB 260714B: AstroSat CZTI detection
  7. GRB 260714B: Fermi GBM Detection
  8. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  9. EP260713a: Einstein Probe detection of an X-ray transient
  10. EP260623a: KAIT optical observations
  11. EP260711a: EP-FXT follow-up observation
  12. GRB 260708A: GRANDMA Optical Observations
  13. GRB 260708A: LCO optical observations
  14. EP260711a: Einstein Probe detection of an X-ray transient
  15. GRB 260710A: Fermi GBM Detection
  16. GRB 260709A: SVOM/GRM detection
  17. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  18. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  19. GRB 260708A: Glowbug gamma-ray detection
  20. GRB 260706A : GRANDMA Upper limits
  21. GRB 260708A: Kilonova-Catcher optical afterglow detection
  22. IceCube-260708A: One candidate from the Zwicky Transient Facility
  23. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  24. GRB 260705B: SVOM/GRM observation
  25. GRB 260706A: Further EP-FXT follow-up 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 260705C: Glowbug gamma-ray detection of a short burst
  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. IPN triangulation of GRB 260627A
  37. IceCube260704A: OHP/T193 optical observations
  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 260704A: SVOM detection of a possible GRB
  42. EP260703a: EP-WXT detection of a fast X-ray transient
  43. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  44. GRB 260623A: Glowbug gamma-ray detection
  45. GRB 260614B: ATCA Radio Upper Limits
  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. EP260623a: Liverpool Telescope optical observations
  53. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  54. EP260623a: WINTER J-band observations
  55. GRB 260617A: Glowbug gamma-ray detection of a short burst
  56. IPN triangulation of GRB 260605A
  57. EP260623a: Optical follow-up observations with Kinder
  58. EP260623a: SVOM/VT optical observations
  59. EP260623a: TRT optical observations
  60. EP260623a: REM optical/NIR afterglow detection
  61. EP 260623a: COLIBRÍ optical observations
  62. EP260623a: Las Cumbres discovery of the optical counterpart
  63. EP260623a: Einstein Probe detection of an X-ray transient
  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. GRB 260619A: TRT optical counterpart confirmation
  69. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  70. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  71. Konus-Wind detection of GRB 260617A
  72. GRB 260616B: AstroSat CZTI detection
  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: EP-FXT follow-up observation
  79. EP260618a: LCO optical counterpart confirmation
  80. EP260618a: COLIBRÍ optical counterpart candidate
  81. GRB 260619A: SVOM possible detection of a faint burst
  82. IPN triangulation of GRB 260617A (short)
  83. EP260618a: EP-WXT detection of an X-ray transient
  84. GRB 260610B: AbAO optical observations
  85. GRB 260506B: cubesat Avion detection
  86. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  87. GRB 260616A: GECAM-B observation
  88. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  89. GRB 260429A: cubesat Avion detection
  90. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  91. GRB 260614A: AstroSat CZTI detection
  92. EP260616a: EP-WXT detection of a fast X-ray transient
  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 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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