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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"

15247 results found.

  1. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  2. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  4. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  5. GRB 260731A: AstroSat CZTI detection of a long burst
  6. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  7. GRB 260730B: AstroSat CZTI detection
  8. EP260731a: COLIBRÍ optical upper limit
  9. GRB 260727A: SVOM/ECLAIRs refined analysis
  10. GRB 260726A: SVOM/ECLAIRs refined analysis
  11. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  12. EP260729a: Einstein Probe detection of an X-ray transient
  13. GRB 260727A: AbAO and SAO RAS optical observations
  14. GRB 260726A: EP-FXT follow-up observations
  15. GRB 260727A: SVOM/GRM observation
  16. GRB 260726A: Fermi GBM Observation
  17. EP260727a: 1.5m OSN optical counterpart detection
  18. Konus-Wind detection of GRB 260727A
  19. GRB 260726A: Liverpool Telescope optical observations
  20. EP260727a: Liverpool Telescope confirmation of optical counterpart
  21. GRB 260727A: EP/FXT follow-up observations
  22. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  23. EP260723a: SVOM/ECLAIRs Upper Limit
  24. GRB 260727A: AstroSat CZTI detection
  25. GRB 260727A: SVOM detection of a bright long burst
  26. GRB 260726A: SVOM detection of a burst
  27. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  28. EP260723a: further EP-FXT follow-up observation
  29. GRB 260616A: cubesat Avion detection
  30. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  31. GRB 260602B: cubesat Avion detection
  32. GRB 260601A: cubesat Avion detection
  33. EP260723a: EP-FXT follow-up observation
  34. GRB 260718A: SVOM/ECLAIRs refined analysis
  35. EP260723a: COLIBRÍ optical observations
  36. EP260723a: NOT optical conterpart confirmation
  37. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  38. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  39. Konus-Wind detection of GRB 260721A
  40. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  41. Konus-Wind detection of GRB 260714B
  42. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  43. GRB 260705A: Retraction of optical counterpart
  44. GRB 260714B: Insight-HXMT/HE detection
  45. GRB 260718A: EP-FXT follow-up observation
  46. GRB 260718A: LCO optical upper limits
  47. GRB 260711A: SVOM/GRM observation
  48. GRB 260710A: SVOM/GRM observation
  49. GRB 260718A: Fermi GBM Observation
  50. GRB 260718A : GRANDMA and KNC upper limits
  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. sb26071506: SVOM detection of a X-ray transient
  59. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  60. EP260703a: SVOM/ECLAIRs Upper Limit
  61. GRB 260710A: AstroSat CZTI detection
  62. GRB 260709A: AstroSat CZTI detection
  63. GRB 260714B: AstroSat CZTI detection
  64. GRB 260714B: Fermi-LAT detection
  65. GRB 260714B: Fermi GBM Detection
  66. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  67. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  68. GRB 260706A: ATCA detection of possible radio counterpart
  69. GRB 260705A: ATCA radio observations
  70. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  71. EP260711a: EP-FXT follow-up observation
  72. GRB 260708A: GRANDMA Optical Observations
  73. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  74. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  75. GRB 260710A: Insight-HXMT/HE detection
  76. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  77. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  78. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 260708A: LCO optical observations
  80. GRB 260710A: Fermi GBM Detection
  81. GRB 260709A: SVOM/GRM detection
  82. GRB 260709A: GECAM-B observation
  83. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  84. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  85. GRB 260705C: AstroSat CZTI detection
  86. GRB 260704A: SVOM/ECLAIRs refined analysis
  87. GRB 260706A : GRANDMA Upper limits
  88. GRB 260708A: Kilonova-Catcher optical afterglow detection
  89. GRB 260708A: GECAM-B observation of a burst
  90. IceCube-260708A: One candidate from the Zwicky Transient Facility
  91. GRB 260708A: Fermi-GBM observation
  92. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 260708A: Fermi-LAT detection
  94. GRB 260705B: SVOM/GRM observation
  95. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  96. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  97. GRB 260706A: SVOM/ECLAIRs refined analysis
  98. GRB 260706A: SVOM/GRM observation
  99. IceCube-260704A: No candidates from the Zwicky Transient Facility
  100. GRB 260706A: Fermi GBM Observation

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