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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"

41694 results found.

  1. Konus-Wind detection of GRB 260727A
  2. GRB 260726A: Liverpool Telescope optical observations
  3. GRB 260727A: Liverpool Telescope optical upper limits
  4. EP260727a: Liverpool Telescope confirmation of optical counterpart
  5. EP260727a: NUTTELA-TAO Early Optical Limits
  6. GRB 260727A: EP/FXT follow-up observations
  7. EP260727a: Einstein Probe detection of an X-ray transient
  8. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  9. GRB 260727A: Glowbug gamma-ray detection
  10. GRB 260726A: J-band upper limit with WINTER
  11. GRB 260727A: J-band upper limit with WINTER
  12. GRB 260726A: SVOM/VT optical candidate
  13. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  14. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  15. EP260723a: SVOM/ECLAIRs Upper Limit
  16. GRB 260727A: GOTO early optical upper limit
  17. GRB 260727A: AstroSat CZTI detection
  18. GRB 260727A: Kilonova-Catcher optical upper limit
  19. GRB 260727A: LCO optical upper limits
  20. Fermi GRB 260726A: Global MASTER-Net observations report
  21. GRB 260727A: SVOM detection of a bright long burst
  22. GRB 260726A: SVOM detection of a burst
  23. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  24. EP260723a: further EP-FXT follow-up observation
  25. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  26. EP260725a: EP-WXT detection of an X-ray transient
  27. GRB 260616A: cubesat Avion detection
  28. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  29. GRB 260602B: cubesat Avion detection
  30. GRB 260601A: cubesat Avion detection
  31. EP260723a: EP-FXT follow-up observation
  32. IPN triangulation of GRB 260706B
  33. GRB 260718A: SVOM/ECLAIRs refined analysis
  34. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  35. EP260723a: SVOM/VT optical observation
  36. EP260723a: COLIBRÍ optical observations
  37. EP260723a: NOT optical conterpart confirmation
  38. EP260723a: Liverpool Telescope likely optical counterpart
  39. EP260723a: EP-WXT detection of a fast X-ray transient
  40. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  42. IceCube Alert 260722A: Global MASTER-Net observations report
  43. Konus-Wind detection of GRB 260721A
  44. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  45. Fermi GBM trigger 806384210/260722151 is not a GRB
  46. GRB 260721A: NuSTAR detection of prompt emission
  47. Konus-Wind detection of GRB 260714B
  48. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  49. GRB 260705A: Retraction of optical counterpart
  50. GRB 260714B: Insight-HXMT/HE detection
  51. GRB 260718A: EP-FXT follow-up observation
  52. Fermi trigger No 806104130: Global MASTER-Net observations report
  53. Fermi GRB 260718A: Global MASTER-Net observations report
  54. GRB 260718A: LCO optical upper limits
  55. GRB 260711A: SVOM/GRM observation
  56. GRB 260710A: SVOM/GRM observation
  57. GRB 260718A: Fermi GBM Observation
  58. GRB 260718A : GRANDMA and KNC upper limits
  59. GRB 260718A: SVOM/VT optical upper limits
  60. GRB 260718A: SVOM/VT optical upper limits from VHF data
  61. GRB 260718A: SVOM detection of a burst
  62. GRB 260714B: SVOM/GRM observation
  63. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  64. GRB 260714B: GECAM-B observation of a burst
  65. GRB 260618B: EP-FXT follow-up observation upper limit
  66. GRB 260714B: COLIBRÍ optical counterpart candidate
  67. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  68. SVOM sb26071506: Global MASTER-Net observations report
  69. sb26071506: SVOM detection of a X-ray transient
  70. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  71. EP260703a: SVOM/ECLAIRs Upper Limit
  72. GRB 260710A: AstroSat CZTI detection
  73. GRB 260709A: AstroSat CZTI detection
  74. GRB 260714B: AstroSat CZTI detection
  75. GRB 260714B: Fermi-LAT detection
  76. GRB 260714B: Fermi GBM Detection
  77. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  78. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  79. GRB 260706A: ATCA detection of possible radio counterpart
  80. GRB 260705A: ATCA radio observations
  81. EP260713a: Einstein Probe detection of an X-ray transient
  82. GRB 260619A: SVOM/VT continuous optical observations
  83. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  84. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  85. EP260623a: KAIT optical observations
  86. EP260711a: EP-FXT follow-up observation
  87. GRB 260708A: GRANDMA Optical Observations
  88. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  89. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  90. GRB 260710A: Insight-HXMT/HE detection
  91. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  92. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  94. GRB 260708A: LCO optical observations
  95. EP260711a: Einstein Probe detection of an X-ray transient
  96. GRB 260710A: Fermi GBM Detection
  97. GRB 260709A: SVOM/GRM detection
  98. GRB 260709A: GECAM-B observation
  99. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  100. IceCube-260708A: Observations with the Vera C. Rubin Observatory

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