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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"

32493 results found.

  1. GRB 260727A: GOTO early optical upper limit
  2. GRB 260727A: AstroSat CZTI detection
  3. GRB 260727A: Kilonova-Catcher optical upper limit
  4. GRB 260727A: LCO optical upper limits
  5. Fermi GRB 260726A: Global MASTER-Net observations report
  6. GRB 260726A: SVOM detection of a burst
  7. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  8. EP260723a: further EP-FXT follow-up observation
  9. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  10. GRB 260616A: cubesat Avion detection
  11. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  12. GRB 260602B: cubesat Avion detection
  13. GRB 260601A: cubesat Avion detection
  14. EP260723a: EP-FXT follow-up observation
  15. IPN triangulation of GRB 260706B
  16. GRB 260718A: SVOM/ECLAIRs refined analysis
  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. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  22. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  23. Konus-Wind detection of GRB 260721A
  24. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 260721A: NuSTAR detection of prompt emission
  26. Konus-Wind detection of GRB 260714B
  27. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  28. GRB 260705A: Retraction of optical counterpart
  29. GRB 260714B: Insight-HXMT/HE detection
  30. GRB 260718A: EP-FXT follow-up observation
  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. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  48. EP260703a: SVOM/ECLAIRs Upper Limit
  49. GRB 260710A: AstroSat CZTI detection
  50. GRB 260709A: AstroSat CZTI detection
  51. GRB 260714B: AstroSat CZTI detection
  52. GRB 260714B: Fermi-LAT detection
  53. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  54. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  55. GRB 260706A: ATCA detection of possible radio counterpart
  56. GRB 260705A: ATCA radio observations
  57. GRB 260619A: SVOM/VT continuous optical observations
  58. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  59. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  60. EP260623a: KAIT optical observations
  61. EP260711a: EP-FXT follow-up observation
  62. GRB 260708A: GRANDMA Optical Observations
  63. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  64. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  65. GRB 260710A: Insight-HXMT/HE detection
  66. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  67. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  68. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 260708A: LCO optical observations
  70. GRB 260710A: Fermi GBM Detection
  71. GRB 260709A: SVOM/GRM detection
  72. GRB 260709A: GECAM-B observation
  73. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  74. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  75. GRB 260705C: AstroSat CZTI detection
  76. GRB 260708A: Glowbug gamma-ray detection
  77. GRB 260704A: SVOM/ECLAIRs refined analysis
  78. GRB 260706A : GRANDMA Upper limits
  79. GRB 260708A: Kilonova-Catcher optical afterglow detection
  80. GRB 260708A: GECAM-B observation of a burst
  81. IceCube-260708A: One candidate from the Zwicky Transient Facility
  82. GRB 260708A: Fermi-GBM observation
  83. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  84. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260708A: Fermi-LAT detection
  86. GRB 260705B: SVOM/GRM observation
  87. GRB 260706A: Further EP-FXT follow-up observation
  88. GRB 260706A: SVOM/VT optical upper limits
  89. EP260707a (by EP-FXT): NOT optical upper limit
  90. EP260707a is not a real source
  91. EP260707a: LCOGT Optical Upper Limit
  92. EP260707a: TRT optical upper limit
  93. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  94. GRB 260705C: Glowbug gamma-ray detection of a short burst
  95. GRB 260706A: SVOM/ECLAIRs refined analysis
  96. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  97. GRB 260706A: SVOM/GRM observation
  98. GRB 260706A: REM optical/NIR observations
  99. IceCube-260704A: No candidates from the Zwicky Transient Facility
  100. GRB 260706A: LCO optical upper limit

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