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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"

14823 results found.

  1. EP260806a: LCO likely optical counterpart
  2. EP260806a: Einstein Probe detection of an X-ray transient
  3. GRB 260715A: cubesat Avion detection
  4. GRB 260709A: cubesat Avion detection
  5. GRB 260708A: cubesat Avion detection
  6. SN 2026stf / GRB 260708A: ATLAS forced photometry
  7. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 260730B: Glowbug gamma-ray detection
  9. GRB 260805C: Glowbug gamma-ray detection
  10. GRB 260805B: Glowbug gamma-ray detection
  11. GRB 260805B: Fermi GBM Final Localization
  12. GRB 260804A: Glowbug gamma-ray detection
  13. GRB 260805A: Fermi GBM Final Localization
  14. AT 2026wki: EP/FXT follow-up observations
  15. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  16. GRB 260804A: Fermi GBM Final Real-time Localization
  17. GRB 260803A: Fermi GBM Final Real-time Localization
  18. GRB 260802B: Fermi GBM Final Localization
  19. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  20. GRB 260731A: AstroSat CZTI detection of a long burst
  21. GRB 260730B: AstroSat CZTI detection
  22. EP260731a: NOT optical upper limit
  23. GRB 260730B: NuSTAR detection of prompt emission
  24. EP260731a: Einstein Probe detection of an X-ray transient
  25. GRB260730A: Fermi GBM Final Localization
  26. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  27. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  28. EP260729a: Einstein Probe detection of an X-ray transient
  29. EP260727a: SAO RAS optical observations
  30. EP260728a: Einstein Probe detection of a fast X-ray transient
  31. EP260727a: 1.5m OSN optical counterpart detection
  32. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  33. EP260727a: OHP/T193 optical observations
  34. Konus-Wind detection of GRB 260727A
  35. GRB 260726A: Liverpool Telescope optical observations
  36. EP260727a: Liverpool Telescope confirmation of optical counterpart
  37. EP260727a: NUTTELA-TAO Early Optical Limits
  38. GRB 260728A: Fermi GBM Final Localization
  39. EP260727a: Einstein Probe detection of an X-ray transient
  40. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  41. GRB 260727A: Glowbug gamma-ray detection
  42. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  43. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  44. GRB 260727A: AstroSat CZTI detection
  45. GRB 260727B: Fermi GBM Final Real-time Localization
  46. GRB 260727A: SVOM detection of a bright long burst
  47. GRB 260726A: SVOM detection of a burst
  48. GRB 260726A: Fermi GBM Final Real-time Localization
  49. EP260723a: further EP-FXT follow-up observation
  50. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  51. EP260725a: EP-WXT detection of an X-ray transient
  52. GRB 260616A: cubesat Avion detection
  53. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  54. GRB 260602B: cubesat Avion detection
  55. GRB 260601A: cubesat Avion detection
  56. EP260723a: EP-FXT follow-up observation
  57. EP260723a: SVOM/VT optical observation
  58. EP260723a: COLIBRÍ optical observations
  59. EP260723a: NOT optical conterpart confirmation
  60. EP260723a: Liverpool Telescope likely optical counterpart
  61. EP260723a: EP-WXT detection of a fast X-ray transient
  62. GRB 260723A: Fermi GBM Final Localization
  63. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  64. Konus-Wind detection of GRB 260721A
  65. GRB 260722A: Fermi GBM Final Real-time Localization
  66. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 260721A: NuSTAR detection of prompt emission
  68. Konus-Wind detection of GRB 260714B
  69. GRB 260705A: Retraction of optical counterpart
  70. GRB 260714B: Insight-HXMT/HE detection
  71. GRB 260718A: SVOM/VT optical upper limits
  72. GRB 260718A: SVOM/VT optical upper limits from VHF data
  73. GRB 260718A: SVOM detection of a burst
  74. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  75. sb26071506: SVOM detection of a X-ray transient
  76. GRB 260715A: Fermi GBM Final Real-time Localization
  77. GRB 260710A: AstroSat CZTI detection
  78. GRB 260709A: AstroSat CZTI detection
  79. GRB 260714B: AstroSat CZTI detection
  80. GRB 260714B: Fermi-LAT detection
  81. GRB 260714B: Fermi GBM Detection
  82. GRB 260714B: Fermi GBM Final Real-time Localization
  83. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  84. GRB 260706A: ATCA detection of possible radio counterpart
  85. GRB 260714A: Fermi GBM Final Real-time Localization
  86. EP260713a: Einstein Probe detection of an X-ray transient
  87. GRB 260619A: SVOM/VT continuous optical observations
  88. EP260711a: EP-FXT follow-up observation
  89. GRB 260710A: Insight-HXMT/HE detection
  90. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  91. EP260711a: Einstein Probe detection of an X-ray transient
  92. GRB 260710A: Fermi GBM Detection
  93. GRB 260709A: SVOM/GRM detection
  94. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  95. GRB 260705C: AstroSat CZTI detection
  96. GRB 260710A: Fermi GBM Final Real-time Localization
  97. GRB 260708A: Glowbug gamma-ray detection
  98. GRB 260708A: Kilonova-Catcher optical afterglow detection
  99. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  100. GRB 260709A: Fermi GBM Final Real-time Localization

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