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

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