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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. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  2. EP260725a: EP-WXT detection of an X-ray transient
  3. GRB 260616A: cubesat Avion detection
  4. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  5. GRB 260602B: cubesat Avion detection
  6. GRB 260601A: cubesat Avion detection
  7. EP260723a: EP-FXT follow-up observation
  8. IPN triangulation of GRB 260706B
  9. GRB 260718A: SVOM/ECLAIRs refined analysis
  10. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  11. EP260723a: SVOM/VT optical observation
  12. EP260723a: COLIBRÍ optical observations
  13. EP260723a: NOT optical conterpart confirmation
  14. EP260723a: Liverpool Telescope likely optical counterpart
  15. EP260723a: EP-WXT detection of a fast X-ray transient
  16. GRB 260723A: Fermi GBM Final Localization
  17. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  19. IceCube Alert 260722A: Global MASTER-Net observations report
  20. Konus-Wind detection of GRB 260721A
  21. GRB 260722A: Fermi GBM Final Real-time Localization
  22. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  23. Fermi GBM trigger 806384210/260722151 is not a GRB
  24. GRB 260721A: NuSTAR detection of prompt emission
  25. Konus-Wind detection of GRB 260714B
  26. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  27. GRB 260705A: Retraction of optical counterpart
  28. GRB 260714B: Insight-HXMT/HE detection
  29. GRB 260718A: EP-FXT follow-up observation
  30. Fermi trigger No 806104130: Global MASTER-Net observations report
  31. Fermi GRB 260718A: Global MASTER-Net observations report
  32. GRB 260718A: LCO optical upper limits
  33. GRB 260711A: SVOM/GRM observation
  34. GRB 260710A: SVOM/GRM observation
  35. GRB 260718A: Fermi GBM Observation
  36. GRB 260718A : GRANDMA and KNC upper limits
  37. GRB 260718A: SVOM/VT optical upper limits
  38. GRB 260718A: SVOM/VT optical upper limits from VHF data
  39. GRB 260718A: SVOM detection of a burst
  40. GRB 260714B: SVOM/GRM observation
  41. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  42. GRB 260714B: GECAM-B observation of a burst
  43. GRB 260618B: EP-FXT follow-up observation upper limit
  44. GRB 260714B: COLIBRÍ optical counterpart candidate
  45. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  46. SVOM sb26071506: Global MASTER-Net observations report
  47. sb26071506: SVOM detection of a X-ray transient
  48. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  49. GRB 260715A: Fermi GBM Final Real-time Localization
  50. EP260703a: SVOM/ECLAIRs Upper Limit
  51. GRB 260710A: AstroSat CZTI detection
  52. GRB 260709A: AstroSat CZTI detection
  53. GRB 260714B: AstroSat CZTI detection
  54. GRB 260714B: Fermi-LAT detection
  55. GRB 260714B: Fermi GBM Detection
  56. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  57. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 260714B: Fermi GBM Final Real-time Localization
  59. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  60. GRB 260706A: ATCA detection of possible radio counterpart
  61. GRB 260705A: ATCA radio observations
  62. GRB 260714A: Fermi GBM Final Real-time Localization
  63. EP260713a: Einstein Probe detection of an X-ray transient
  64. GRB 260619A: SVOM/VT continuous optical observations
  65. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  66. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  67. EP260623a: KAIT optical observations
  68. EP260711a: EP-FXT follow-up observation
  69. GRB 260708A: GRANDMA Optical Observations
  70. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  71. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  72. GRB 260710A: Insight-HXMT/HE detection
  73. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  74. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  75. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 260708A: LCO optical observations
  77. EP260711a: Einstein Probe detection of an X-ray transient
  78. GRB 260710A: Fermi GBM Detection
  79. GRB 260709A: SVOM/GRM detection
  80. GRB 260709A: GECAM-B observation
  81. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  82. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  83. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  84. GRB 260705C: AstroSat CZTI detection
  85. GRB 260710A: Fermi GBM Final Real-time Localization
  86. GRB 260708A: Glowbug gamma-ray detection
  87. GRB 260704A: SVOM/ECLAIRs refined analysis
  88. GRB 260706A : GRANDMA Upper limits
  89. GRB 260708A: Kilonova-Catcher optical afterglow detection
  90. GRB 260708A: GECAM-B observation of a burst
  91. IceCube-260708A: One candidate from the Zwicky Transient Facility
  92. GRB 260708A: Fermi-GBM observation
  93. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  94. IceCube Alert 260709A: Global MASTER-Net observations report
  95. GRB 260709A: Fermi GBM Final Real-time Localization
  96. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  97. LAT GRB260708.42: Global MASTER-Net observations report
  98. GRB260708B: MAXI/GSC detection
  99. GRB 260708A: Fermi-LAT detection
  100. GRB 260705B: SVOM/GRM observation

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