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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"

27772 results found.

  1. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  3. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  4. GRB 260809A: SVOM detection of a faint burst
  5. GRB 260808A: NuSTAR detection of prompt emission
  6. EP260809a: Einstein Probe detection of an X-ray transient
  7. GRB 260808C: Fermi GBM Final Real-time Localization
  8. GRB 260808B: SVOM detection of a faint burst
  9. GRB 260808A: Fermi GBM Final Real-time Localization
  10. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  11. GRB 260807A: SVOM possible detection of a faint burst
  12. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  13. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  14. EP260806a: Einstein Probe detection of an X-ray transient
  15. GRB 260715A: cubesat Avion detection
  16. GRB 260709A: cubesat Avion detection
  17. GRB 260708A: cubesat Avion detection
  18. SN 2026stf / GRB 260708A: ATLAS forced photometry
  19. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 260730B: Glowbug gamma-ray detection
  21. GRB 260805C: Glowbug gamma-ray detection
  22. GRB 260805B: Glowbug gamma-ray detection
  23. GRB 260805B: Fermi GBM Final Localization
  24. GRB 260804A: Glowbug gamma-ray detection
  25. GRB 260805A: Fermi GBM Final Localization
  26. AT 2026wki: EP/FXT follow-up observations
  27. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  28. GRB 260804A: Fermi GBM Final Real-time Localization
  29. GRB 260803A: Fermi GBM Final Real-time Localization
  30. GRB 260802B: Fermi GBM Final Localization
  31. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  32. GRB 260731A: AstroSat CZTI detection of a long burst
  33. GRB 260730B: AstroSat CZTI detection
  34. GRB 260730B: NuSTAR detection of prompt emission
  35. EP260731a: Einstein Probe detection of an X-ray transient
  36. GRB260730A: Fermi GBM Final Localization
  37. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  38. EP260729a: Einstein Probe detection of an X-ray transient
  39. EP260728a: Einstein Probe detection of a fast X-ray transient
  40. EP260727a: 1.5m OSN optical counterpart detection
  41. Konus-Wind detection of GRB 260727A
  42. GRB 260726A: Liverpool Telescope optical observations
  43. EP260727a: Liverpool Telescope confirmation of optical counterpart
  44. GRB 260728A: Fermi GBM Final Localization
  45. EP260727a: Einstein Probe detection of an X-ray transient
  46. GRB 260727A: Glowbug gamma-ray detection
  47. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  48. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  49. GRB 260727A: AstroSat CZTI detection
  50. GRB 260727B: Fermi GBM Final Real-time Localization
  51. GRB 260727A: SVOM detection of a bright long burst
  52. GRB 260726A: SVOM detection of a burst
  53. GRB 260726A: Fermi GBM Final Real-time Localization
  54. EP260723a: further EP-FXT follow-up observation
  55. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  56. EP260725a: EP-WXT detection of an X-ray transient
  57. GRB 260616A: cubesat Avion detection
  58. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  59. GRB 260602B: cubesat Avion detection
  60. GRB 260601A: cubesat Avion detection
  61. EP260723a: EP-FXT follow-up observation
  62. EP260723a: Liverpool Telescope likely optical counterpart
  63. EP260723a: EP-WXT detection of a fast X-ray transient
  64. GRB 260723A: Fermi GBM Final Localization
  65. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  66. Konus-Wind detection of GRB 260721A
  67. GRB 260722A: Fermi GBM Final Real-time Localization
  68. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 260721A: NuSTAR detection of prompt emission
  70. Konus-Wind detection of GRB 260714B
  71. GRB 260705A: Retraction of optical counterpart
  72. GRB 260714B: Insight-HXMT/HE detection
  73. GRB 260718A: SVOM/VT optical upper limits
  74. GRB 260718A: SVOM/VT optical upper limits from VHF data
  75. GRB 260718A: SVOM detection of a burst
  76. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  77. sb26071506: SVOM detection of a X-ray transient
  78. GRB 260715A: Fermi GBM Final Real-time Localization
  79. GRB 260710A: AstroSat CZTI detection
  80. GRB 260709A: AstroSat CZTI detection
  81. GRB 260714B: AstroSat CZTI detection
  82. GRB 260714B: Fermi-LAT detection
  83. GRB 260714B: Fermi GBM Detection
  84. GRB 260714B: Fermi GBM Final Real-time Localization
  85. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  86. GRB 260706A: ATCA detection of possible radio counterpart
  87. GRB 260714A: Fermi GBM Final Real-time Localization
  88. EP260713a: Einstein Probe detection of an X-ray transient
  89. EP260711a: EP-FXT follow-up observation
  90. GRB 260710A: Insight-HXMT/HE detection
  91. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  92. EP260711a: Einstein Probe detection of an X-ray transient
  93. GRB 260710A: Fermi GBM Detection
  94. GRB 260709A: SVOM/GRM detection
  95. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  96. GRB 260705C: AstroSat CZTI detection
  97. GRB 260710A: Fermi GBM Final Real-time Localization
  98. GRB 260708A: Glowbug gamma-ray detection
  99. GRB 260708A: Kilonova-Catcher optical afterglow detection
  100. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection

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