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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"

38363 results found.

  1. GRB 260726A: SVOM/VT optical candidate
  2. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  3. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  4. EP260723a: SVOM/ECLAIRs Upper Limit
  5. GRB 260727A: GOTO early optical upper limit
  6. GRB 260727A: AstroSat CZTI detection
  7. GRB 260727A: Kilonova-Catcher optical upper limit
  8. GRB 260727A: LCO optical upper limits
  9. GRB 260727B: Fermi GBM Final Real-time Localization
  10. GRB 260727A: SVOM detection of a bright long burst
  11. GRB 260726A: SVOM detection of a burst
  12. GRB 260726A: Fermi GBM Final Real-time Localization
  13. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  14. EP260723a: further EP-FXT follow-up observation
  15. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  16. EP260725a: EP-WXT detection of an X-ray transient
  17. GRB 260616A: cubesat Avion detection
  18. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  19. GRB 260602B: cubesat Avion detection
  20. GRB 260601A: cubesat Avion detection
  21. EP260723a: EP-FXT follow-up observation
  22. IPN triangulation of GRB 260706B
  23. GRB 260718A: SVOM/ECLAIRs refined analysis
  24. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  25. EP260723a: SVOM/VT optical observation
  26. EP260723a: COLIBRÍ optical observations
  27. EP260723a: Liverpool Telescope likely optical counterpart
  28. EP260723a: EP-WXT detection of a fast X-ray transient
  29. GRB 260723A: Fermi GBM Final Localization
  30. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  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. GRB 260718A: LCO optical upper limits
  43. GRB 260711A: SVOM/GRM observation
  44. GRB 260710A: SVOM/GRM observation
  45. GRB 260718A: Fermi GBM Observation
  46. GRB 260718A : GRANDMA and KNC upper limits
  47. GRB 260718A: SVOM/VT optical upper limits
  48. GRB 260718A: SVOM/VT optical upper limits from VHF data
  49. GRB 260718A: SVOM detection of a burst
  50. GRB 260714B: SVOM/GRM observation
  51. GRB 260714B: GECAM-B observation of a burst
  52. GRB 260618B: EP-FXT follow-up observation upper limit
  53. GRB 260714B: COLIBRÍ optical counterpart candidate
  54. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  55. SVOM sb26071506: Global MASTER-Net observations report
  56. sb26071506: SVOM detection of a X-ray transient
  57. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  58. GRB 260715A: Fermi GBM Final Real-time Localization
  59. EP260703a: SVOM/ECLAIRs Upper Limit
  60. GRB 260710A: AstroSat CZTI detection
  61. GRB 260709A: AstroSat CZTI detection
  62. GRB 260714B: AstroSat CZTI detection
  63. GRB 260714B: Fermi-LAT detection
  64. GRB 260714B: Fermi GBM Detection
  65. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  66. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 260714B: Fermi GBM Final Real-time Localization
  68. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  69. GRB 260706A: ATCA detection of possible radio counterpart
  70. GRB 260705A: ATCA radio observations
  71. GRB 260714A: Fermi GBM Final Real-time Localization
  72. EP260713a: Einstein Probe detection of an X-ray transient
  73. GRB 260619A: SVOM/VT continuous optical observations
  74. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  75. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  76. EP260623a: KAIT optical observations
  77. EP260711a: EP-FXT follow-up observation
  78. GRB 260708A: GRANDMA Optical Observations
  79. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  80. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  81. GRB 260710A: Insight-HXMT/HE detection
  82. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  83. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260708A: LCO optical observations
  86. EP260711a: Einstein Probe detection of an X-ray transient
  87. GRB 260710A: Fermi GBM Detection
  88. GRB 260709A: SVOM/GRM detection
  89. GRB 260709A: GECAM-B observation
  90. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  91. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  92. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  93. GRB 260705C: AstroSat CZTI detection
  94. GRB 260710A: Fermi GBM Final Real-time Localization
  95. GRB 260708A: Glowbug gamma-ray detection
  96. GRB 260704A: SVOM/ECLAIRs refined analysis
  97. GRB 260706A : GRANDMA Upper limits
  98. GRB 260708A: Kilonova-Catcher optical afterglow detection
  99. GRB 260708A: GECAM-B observation of a burst
  100. IceCube-260708A: One candidate from the Zwicky Transient Facility

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