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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 251214A: AstroSat CZTI detection
  2. GRB 251213A: GECAM-B detection
  3. GRB 251214B: Swift/UVOT Detection
  4. GRB 251215A: Fermi GBM Final Real-time Localization
  5. GRB 251214B: COLIBRÍ observations of the afterglow
  6. EP251214a: EP-FXT non-detection and upper limit
  7. GRB 251214B: 1.3m DFOT optical detection
  8. GRB 251214B: Xinglong-2.16m optical observation
  9. GRB 251214C: Fermi GBM Final Localization
  10. GRB 251214B : MASTER optical afterglow detection
  11. GRB 251214B: Swift detection of a burst with an optical counterpart
  12. GRB 251214B: Fermi GBM Final Real-time Localization
  13. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  14. GRB 251214A: Fermi GBM Final Real-time Localization
  15. EP251212a / GRB 251212A: AstroSat CZTI detection
  16. EP251212a: EP-FXT follow-up observation
  17. GRB 251211B: AstroSat CZTI detection
  18. GRB 251209A: NuSTAR detection of prompt emission
  19. EP251212a: Einstein Probe detection of an X-ray transient
  20. GRB 251211B: Fermi GBM Final Real-time Localization
  21. GRB 251211A: Fermi GBM Final Real-time Localization
  22. GRB 251205A: 1.3m DFOT optical upper limit
  23. GRB 251209A: AstroSat CZTI detection
  24. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  25. EP251130a: Mondy and AbAO optical observations
  26. GRB 251208A: AstroSat CZTI detection
  27. Fermi GBM Sub-Threshold Detection of GRB 251205A
  28. GRB 251208A: Glowbug gamma-ray detection
  29. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  30. GRB 251208B: Swift-XRT afterglow detection
  31. GRB 251209A: Fermi GBM Final Real-time Localization
  32. GRB 251205A: J-band detection with WINTER
  33. GRB 251208B: Fermi-LAT detection
  34. GRB 251208D: SVOM possible detection of a faint burst
  35. GRB 251206A: SVOM detection of a burst through offline search
  36. GRB 251208C: Fermi GBM Final Real-time Localization
  37. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  38. GRB 251208B: Fermi GBM Final Real-time Localization
  39. GRB 251208A: Fermi GBM Final Real-time Localization
  40. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  41. GRB 251205A: Swift/UVOT Detection
  42. Konus-Wind detection of GRB 251118A
  43. GRB 251205A: GOTO optical afterglow detection
  44. Swift GRB 251205A : MASTER OT detection with host galaxy
  45. GRB 251205A: Swift detection of a burst with an optical afterglow
  46. GRB 251126B: Fermi GBM Final Localization
  47. GRB 251203A: Insight-HXMT/HE detection
  48. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  49. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  50. GRB 251202A: SVOM/GRM observation
  51. GRB 251129B: Glowbug gamma-ray detection of a short burst
  52. GRB 251203A: AstroSat CZTI detection
  53. EP251130a: JinShan near-infrared observations
  54. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  55. GRB 251203C: SVOM detection of a burst
  56. GRB 251203B: SVOM detection of a burst
  57. GRB 251201B: Insight-HXMT/HE detection
  58. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  59. EP251130a: MAO/AZT-22 optical observations
  60. GRB 251203A: Fermi GBM Final Real-time Localization
  61. EP251202a / GRB251202A: AstroSat CZTI detection
  62. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  63. GRB 251202B: Fermi GBM Final Real-time Localization
  64. IPN triangulation of GRB 251129B (short/hard)
  65. GRB251129A/EP251129a: Swift UVOT detection
  66. GRB 251129B: AstroSat CZTI detection
  67. GRB 251202A: Swift/UVOT Detection
  68. GRB 251201B: Kilonova-Catcher optical afterglow detection
  69. GRB 251201B: Swift/UVOT Detection
  70. GRB 251130B: Glowbug gamma-ray detection
  71. EP251130a: continued NOT optical observations indicate steep fading phase
  72. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  73. GRB 251202A: GOTO optical afterglow detection
  74. GRB 251126A: SAO RAS optical marginal detection
  75. GRB 251202A: Swift-XRT afterglow detection
  76. EP251129a/GRB 251129A: NOWT Detection
  77. EP251130a: SVOM/VT optical observation
  78. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  79. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  80. GRB 251202A: Fermi GBM Final Real-time Localization
  81. Swift GRB 251201B : MASTER optical counterpart detection
  82. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  83. GRB 251130B: AstroSat CZTI detection
  84. GRB 251201B: Swift detection of a burst with an optical counterpart
  85. GRB 251201B: Fermi GBM Final Real-time Localization
  86. EP251130a: Mondy optical observations
  87. EP251130a: Optical detections with Kinder observations
  88. EP251130a: SAO RAS optical observations
  89. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  90. EP251130a: KAIT optical observations
  91. EP251130A: Optical observation from 1.3m DFOT
  92. EP251130a: JinShan optical observations
  93. GRB 251201A: MAXI/GSC detection
  94. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  95. EP251130a: Swift-XRT counterpart detection
  96. GRB 251130B: Fermi GBM Final Localization Correction
  97. GRB 251130B: Fermi GBM Final Real-time Localization
  98. EP251130a: Einstein Probe detection of an X-ray transient
  99. GRB 251130A: Fermi GBM Final Real-time Localization
  100. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460

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