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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"

14824 results found.

  1. GRB 260603C: AstroSat CZTI detection
  2. EP260610b: Liverpool Telescope optical upper limits
  3. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  4. GRB 260611B: Fermi GBM Final Real-time Localization
  5. GRB 260610B / AT2026owq: Early ATLAS observations
  6. GRB 260610B: TRT optical observation
  7. GRB 260611A: Fermi GBM Final Real-time Localization
  8. EP260610b: NOT optical observation
  9. GRB 260610B: Fermi GBM Final Localization
  10. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  11. GRB 260515A: SOAR optical observations
  12. EP260610a: SVOM/VT optical upper limits
  13. EP260610b: Einstein Probe detection of an X-ray transient
  14. Konus-Wind detection of GRB 260601A
  15. IPN triangulation of GRB 260601A (short/hard)
  16. GRB 260610A: Fermi GBM Final Real-time Localization
  17. EP260610a: Einstein Probe detection of a fast X-ray transient
  18. GRB 260609A: Fermi GBM Final Localization
  19. Konus-Wind detection of GRB 260604C
  20. GRB 260604C: AstroSat CZTI detection
  21. IPN triangulation of GRB 260601B / EP260601a
  22. GRB 260604C: SVOM/ECLAIRs refined analysis
  23. Konus-Wind detection of GRB 260607B
  24. GRB 260608C: Fermi GBM Final Real-time Localization
  25. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  26. GRB 260608B: Fermi GBM Final Localization
  27. GRB 260607B: AstroSat CZTI detection
  28. GRB 260608A: SVOM detection of a burst
  29. GRB 260608A: Fermi GBM Final Real-time Localization
  30. EP260605a: EP-FXT follow-up observation
  31. GRB 260607A: TRT optical observations
  32. GRB 260604A: SVOM/GRM detection
  33. GRB 260607B: Fermi-LAT detection
  34. GRB 260607B: Fermi GBM Final Localization Correction
  35. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  36. GRB 260607A: Fermi GBM Final Real-time Localization
  37. GRB 260604B: SVOM/GRM detection
  38. GRB 260605A: Insight-HXMT/HE detection
  39. EP260605a: Einstein Probe detection of a fast X-ray transient
  40. GRB 260604A: Glowbug gamma-ray detection
  41. GRB 260604C: Liverpool Telescope optical detection
  42. EP260602d: EP-FXT follow-up observation
  43. EP260602c: EP-FXT follow-up observation
  44. GRB 260601B / EP260601a: AstroSat CZTI detection
  45. GRB 260527A/EP260527a: 6 GHz VLA observations
  46. GRB 260604C: Correction to GCN 44828
  47. GRB 260604C: Kilonova-Catcher optical afterglow detection
  48. GRB 260604C: Jinshan optical observations
  49. EP260602b: J-band upper limit with WINTER
  50. GRB 260604C: LAST detection of optical counterpart candidate
  51. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  52. GRB 260604C: SVOM detection of a long burst
  53. GRB 260604C: Fermi GBM Final Real-time Localization
  54. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  55. GRB 260604B: Fermi GBM Final Real-time Localization
  56. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  57. EP260602a: EP-FXT follow-up observation
  58. EP260603a: Einstein Probe detection of a fast X-ray transient
  59. EP260602d: Optical Upper limits with kinder observations
  60. GRB 260604A: Fermi GBM Final Real-time Localization
  61. EP260602b: Liverpool Telescope observations
  62. EP260602a: Liverpool Telescope optical upper limits
  63. EP260602b: Liverpool Telescope and LCO observations
  64. GRB 260603B: Fermi GBM Final Localization
  65. EP260602a: GTC and Liverpool Telescope optical observations
  66. Konus-Wind detection of GRB 260601B/EP260601a
  67. EP260601a/GRB 260601B: EP-FXT follow-up observation
  68. EP260602b: EP-FXT follow-up observation
  69. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  70. EP260602a: NOT NIR J-band observations
  71. EP260602d: Einstein Probe detection of a fast X-ray transient
  72. EP260602c: Einstein Probe detection of a fast X-ray transient
  73. EP260602a: COLIBRÍ optical observations
  74. GRB260601B/EP260601a: NOT near-infrared observations
  75. GRB 260603A: SVOM detection of a burst
  76. EP260602b: Einstein Probe detection of a fast X-ray transient
  77. GRB 260601B/EP260601a: Insight-HXMT detection
  78. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  79. GRB 260602B: Fermi GBM Final Localization
  80. GRB 260602A: Fermi GBM Final Real-time Localization
  81. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  82. EP260602a: Optical upper limits with Kinder observations
  83. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  84. EP260602a: Einstein Probe detection of a fast X-ray transient
  85. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  86. EP260601a: Einstein Probe detection of an X-ray transient
  87. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  88. GRB 260601A: Glowbug gamma-ray detection of a short burst
  89. GRB 260531B: Glowbug gamma-ray detection
  90. GRB 260516D: VLA radio detection
  91. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  92. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  93. GRB 260601A: Fermi GBM Final Real-time Localization
  94. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  95. GRB 260531C: Fermi GBM Final Localization Correction
  96. AT2026nik: EP-FXT X-ray counterpart
  97. GRB 260531B: Fermi GBM Final Real-time Localization
  98. GRB 260531A: MAXI/GSC detection
  99. IPN triangulation of GRB 260527A / EP260527a
  100. GRB 260530B: SVOM/GRM detection of a possible bright short GRB

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