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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"

28066 results found.

  1. GRB 260810A: AstroSat CZTI detection of a long burst
  2. EP260812a: Einstein Probe detection of an X-ray transient
  3. GRB 260808B: SVOM/VT optical re-brightening at day 3
  4. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  5. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  6. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  7. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  8. GRB 260806A: Glowbug gamma-ray detection
  9. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  11. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  12. GRB 260809A: NOT optical observations
  13. GRB260809A: MAO/AZT-22 optical observations
  14. GRB260809A: OHP/T193 optical observations
  15. GRB 260809A: SVOM detection of a faint burst
  16. GRB 260808B: NOT optical observations
  17. GRB 260808A: NuSTAR detection of prompt emission
  18. GRB260808B: OHP/T193 optical observations
  19. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  20. EP260809a: Einstein Probe detection of an X-ray transient
  21. GRB 260808B: SVOM/VT optical afterglow confirmation
  22. GRB 260808C: Fermi GBM Final Real-time Localization
  23. GRB 260808B: SVOM detection of a faint burst
  24. GRB 260808A: Fermi GBM Final Real-time Localization
  25. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  26. GRB 260807A: SVOM possible detection of a faint burst
  27. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  28. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  29. EP260806a: Einstein Probe detection of an X-ray transient
  30. GRB 260715A: cubesat Avion detection
  31. GRB 260709A: cubesat Avion detection
  32. GRB 260708A: cubesat Avion detection
  33. SN 2026stf / GRB 260708A: ATLAS forced photometry
  34. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 260730B: Glowbug gamma-ray detection
  36. GRB 260805C: Glowbug gamma-ray detection
  37. GRB 260805B: Glowbug gamma-ray detection
  38. GRB 260805B: Fermi GBM Final Localization
  39. GRB 260804A: Glowbug gamma-ray detection
  40. GRB 260805A: Fermi GBM Final Localization
  41. AT 2026wki: EP/FXT follow-up observations
  42. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260804A: Fermi GBM Final Real-time Localization
  44. GRB 260803A: Fermi GBM Final Real-time Localization
  45. GRB 260802B: Fermi GBM Final Localization
  46. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  47. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  48. GRB 260731A: AstroSat CZTI detection of a long burst
  49. GRB 260730B: AstroSat CZTI detection
  50. GRB 260730B: NuSTAR detection of prompt emission
  51. EP260731a: Einstein Probe detection of an X-ray transient
  52. GRB260730A: Fermi GBM Final Localization
  53. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  54. EP260729a: Einstein Probe detection of an X-ray transient
  55. EP260728a: Einstein Probe detection of a fast X-ray transient
  56. EP260727a: 1.5m OSN optical counterpart detection
  57. Konus-Wind detection of GRB 260727A
  58. GRB 260726A: Liverpool Telescope optical observations
  59. EP260727a: Liverpool Telescope confirmation of optical counterpart
  60. GRB 260728A: Fermi GBM Final Localization
  61. EP260727a: Einstein Probe detection of an X-ray transient
  62. GRB 260727A: Glowbug gamma-ray detection
  63. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  64. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  65. GRB 260727A: AstroSat CZTI detection
  66. GRB 260727B: Fermi GBM Final Real-time Localization
  67. GRB 260727A: SVOM detection of a bright long burst
  68. GRB 260726A: SVOM detection of a burst
  69. GRB 260726A: Fermi GBM Final Real-time Localization
  70. EP260723a: further EP-FXT follow-up observation
  71. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  72. EP260725a: EP-WXT detection of an X-ray transient
  73. GRB 260616A: cubesat Avion detection
  74. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  75. GRB 260602B: cubesat Avion detection
  76. GRB 260601A: cubesat Avion detection
  77. EP260723a: EP-FXT follow-up observation
  78. EP260723a: Liverpool Telescope likely optical counterpart
  79. EP260723a: EP-WXT detection of a fast X-ray transient
  80. GRB 260723A: Fermi GBM Final Localization
  81. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  82. Konus-Wind detection of GRB 260721A
  83. GRB 260722A: Fermi GBM Final Real-time Localization
  84. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260721A: NuSTAR detection of prompt emission
  86. Konus-Wind detection of GRB 260714B
  87. GRB 260705A: Retraction of optical counterpart
  88. GRB 260714B: Insight-HXMT/HE detection
  89. GRB 260718A: SVOM/VT optical upper limits
  90. GRB 260718A: SVOM/VT optical upper limits from VHF data
  91. GRB 260718A: SVOM detection of a burst
  92. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  93. sb26071506: SVOM detection of a X-ray transient
  94. GRB 260715A: Fermi GBM Final Real-time Localization
  95. GRB 260710A: AstroSat CZTI detection
  96. GRB 260709A: AstroSat CZTI detection
  97. GRB 260714B: AstroSat CZTI detection
  98. GRB 260714B: Fermi-LAT detection
  99. GRB 260714B: Fermi GBM Detection
  100. GRB 260714B: Fermi GBM Final Real-time Localization

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