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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"
  1. Fermi GRB 260726A: Global MASTER-Net observations report
  2. GRB 260727A: SVOM detection of a bright long burst
  3. GRB 260726A: SVOM detection of a burst
  4. GRB 260726A: Fermi GBM Final Real-time Localization
  5. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  6. EP260723a: further EP-FXT follow-up observation
  7. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  8. EP260725a: EP-WXT detection of an X-ray transient
  9. GRB 260616A: cubesat Avion detection
  10. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  11. GRB 260602B: cubesat Avion detection
  12. GRB 260601A: cubesat Avion detection
  13. EP260723a: EP-FXT follow-up observation
  14. IPN triangulation of GRB 260706B
  15. GRB 260718A: SVOM/ECLAIRs refined analysis
  16. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  17. EP260723a: SVOM/VT optical observation
  18. EP260723a: COLIBRÍ optical observations
  19. EP260723a: NOT optical conterpart confirmation
  20. EP260723a: Liverpool Telescope likely optical counterpart
  21. EP260723a: EP-WXT detection of a fast X-ray transient
  22. GRB 260723A: Fermi GBM Final Localization
  23. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  25. IceCube Alert 260722A: Global MASTER-Net observations report
  26. Konus-Wind detection of GRB 260721A
  27. GRB 260722A: Fermi GBM Final Real-time Localization
  28. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  29. Fermi GBM trigger 806384210/260722151 is not a GRB
  30. GRB 260721A: NuSTAR detection of prompt emission
  31. Konus-Wind detection of GRB 260714B
  32. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  33. GRB 260705A: Retraction of optical counterpart
  34. GRB 260714B: Insight-HXMT/HE detection
  35. GRB 260718A: EP-FXT follow-up observation
  36. Fermi trigger No 806104130: Global MASTER-Net observations report
  37. Fermi GRB 260718A: Global MASTER-Net observations report
  38. GRB 260718A: LCO optical upper limits
  39. GRB 260711A: SVOM/GRM observation
  40. GRB 260710A: SVOM/GRM observation
  41. GRB 260718A: Fermi GBM Observation
  42. GRB 260718A : GRANDMA and KNC upper limits
  43. GRB 260718A: SVOM/VT optical upper limits
  44. GRB 260718A: SVOM/VT optical upper limits from VHF data
  45. GRB 260718A: SVOM detection of a burst
  46. GRB 260714B: SVOM/GRM observation
  47. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  48. GRB 260714B: GECAM-B observation of a burst
  49. GRB 260618B: EP-FXT follow-up observation upper limit
  50. GRB 260714B: COLIBRÍ optical counterpart candidate
  51. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  52. SVOM sb26071506: Global MASTER-Net observations report
  53. sb26071506: SVOM detection of a X-ray transient
  54. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  55. GRB 260715A: Fermi GBM Final Real-time Localization
  56. EP260703a: SVOM/ECLAIRs Upper Limit
  57. GRB 260710A: AstroSat CZTI detection
  58. GRB 260709A: AstroSat CZTI detection
  59. GRB 260714B: AstroSat CZTI detection
  60. GRB 260714B: Fermi-LAT detection
  61. GRB 260714B: Fermi GBM Detection
  62. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  63. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 260714B: Fermi GBM Final Real-time Localization
  65. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  66. GRB 260706A: ATCA detection of possible radio counterpart
  67. GRB 260705A: ATCA radio observations
  68. GRB 260714A: Fermi GBM Final Real-time Localization
  69. EP260713a: Einstein Probe detection of an X-ray transient
  70. GRB 260619A: SVOM/VT continuous optical observations
  71. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  72. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  73. EP260623a: KAIT optical observations
  74. EP260711a: EP-FXT follow-up observation
  75. GRB 260708A: GRANDMA Optical Observations
  76. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  77. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  78. GRB 260710A: Insight-HXMT/HE detection
  79. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  80. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 260708A: LCO optical observations
  83. EP260711a: Einstein Probe detection of an X-ray transient
  84. GRB 260710A: Fermi GBM Detection
  85. GRB 260709A: SVOM/GRM detection
  86. GRB 260709A: GECAM-B observation
  87. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  88. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  89. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  90. GRB 260705C: AstroSat CZTI detection
  91. GRB 260710A: Fermi GBM Final Real-time Localization
  92. GRB 260708A: Glowbug gamma-ray detection
  93. GRB 260704A: SVOM/ECLAIRs refined analysis
  94. GRB 260706A : GRANDMA Upper limits
  95. GRB 260708A: Kilonova-Catcher optical afterglow detection
  96. GRB 260708A: GECAM-B observation of a burst
  97. IceCube-260708A: One candidate from the Zwicky Transient Facility
  98. GRB 260708A: Fermi-GBM observation
  99. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  100. IceCube Alert 260709A: Global MASTER-Net observations report

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