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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"

25630 results found.

  1. GRB 251214B: Fermi GBM Final Real-time Localization
  2. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  3. Fermi GRB 251214A: Global MASTER-Net observations report
  4. GRB 251214A: Fermi GBM Final Real-time Localization
  5. EP251212a: Global MASTER-Net observations report
  6. EP251212a / GRB 251212A: AstroSat CZTI detection
  7. GRB 251209A: NuSTAR detection of prompt emission
  8. EP251212a : COLIBRÍ optical upper limit
  9. EP251212a: Einstein Probe detection of an X-ray transient
  10. Fermi GRB 251211B: Global MASTER-Net observations report
  11. GRB 251211B: Fermi GBM Final Real-time Localization
  12. IceCube-251210A: DDOTI Optical Upper Limit
  13. SVOM GRB251211.12: Global MASTER-Net observations report
  14. GRB 251211A: Fermi GBM Final Real-time Localization
  15. GRB 251209A: Fermi GBM observation
  16. GRB 251205A: 1.3m DFOT optical upper limit
  17. IceCube Alert 251210.46: Global MASTER-Net observations report
  18. EP251130a: Mondy and AbAO optical observations
  19. Fermi GBM Sub-Threshold Detection of GRB 251205A
  20. GRB 251208B: COLIBRÍ optical upper limits
  21. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  22. Fermi GRB 251209A: Global MASTER-Net observations report
  23. Fermi GRB 251208C: Global MASTER-Net observations report
  24. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  25. GRB 251209A: Fermi GBM Final Real-time Localization
  26. GRB 251208B: Fermi GBM Observation
  27. GRB 251208B: GROWTH-India Telescope optical upper limits
  28. GRB 251205A: J-band detection with WINTER
  29. GRB 251208D: Swift-XRT observations
  30. GRB 251208A: SVOM/GRM observation of a short burst
  31. GRB 251208C: SVOM/GRM observation of a short burst
  32. LAT GRB251208.43: Global MASTER-Net observations report
  33. GRB 251205A: Liverpool Telescope further optical follow-up observations
  34. GRB 251208D: LCO optical upper limits
  35. SVOM GRB251208D: Global MASTER-Net observations report
  36. GRB 251208B: Fermi-LAT detection
  37. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  38. GRB 251208D: SVOM possible detection of a faint burst
  39. GRB 251206A: SVOM detection of a burst through offline search
  40. GRB 251208C: Fermi GBM Final Real-time Localization
  41. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  42. GRB 251208B: Fermi GBM Final Real-time Localization
  43. GRB 251208A: Fermi GBM Final Real-time Localization
  44. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  45. GRB 251205A: Liverpool Telescope further optical follow-up observations
  46. SVOM GRB251206.86: Global MASTER-Net observations report
  47. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  48. The EP-WXT trigger 01709249380 is likely a flaring star
  49. GRB 251205A: GROWTH-India Telescope optical observations
  50. GRB 251205A: Swift-BAT refined analysis
  51. GRB 251205A: Swift-XRT refined Analysis
  52. GRB 251205A: Swift/UVOT Detection
  53. GRB 251205A: Liverpool Telescope optical follow-up observations
  54. GRB 251203C: Swift/UVOT Upper Limit
  55. GRB 251205A: COLIBRÍ optical observations
  56. GRB 251205A: GOTO optical afterglow detection
  57. GRB 251205A: NOT optical observations
  58. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  59. GRB 251205A: Swift detection of a burst with an optical afterglow
  60. Swift GRB251205A: Global MASTER-Net observations report
  61. GRB 251126B: Fermi GBM Final Localization
  62. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  63. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  64. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  65. GRB 251201B: SALT spectroscopic redshift z = 1.599
  66. GRB 251203C: J-band observations with WINTER
  67. GRB 251129B: Glowbug gamma-ray detection of a short burst
  68. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  69. GRB 251203C: LCO optical afterglow confirmation
  70. GRB 251203C: SVOM/VT optical counterpart
  71. GRB 251203C: EP-FXT follow-up observation
  72. GRB 251203B: Swift-XRT observations
  73. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  74. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  75. GRB 251203C: LCO optical upper limits
  76. GRB 251203B: LCO optical upper limits
  77. GRB 251203B: SVOM/VT optical observation
  78. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  79. GRB 251203C: SVOM detection of a burst
  80. SVOM GRB251203.77: Global MASTER-Net observations report
  81. SVOM GRB251203B: Global MASTER-Net observations report
  82. GRB 251203B: SVOM detection of a burst
  83. GRB 251203A: Fermi GBM Final Real-time Localization
  84. GRB 251202A / EP251202a: SVOM/VT optical observation
  85. GRB 251201B: Fermi GBM Observation
  86. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  87. Fermi GRB 251202B: Global MASTER-Net observations report
  88. GRB 251202B: Fermi GBM Final Real-time Localization
  89. IPN triangulation of GRB 251129B (short/hard)
  90. GRB251129A/EP251129a: Swift UVOT detection
  91. GRB 251202A: Fermi GBM Observation
  92. GRB 251202A: Swift/UVOT Detection
  93. GRB 251201B: Kilonova-Catcher optical afterglow detection
  94. GRB 251201B: Swift/UVOT Detection
  95. GRB 251130B: Glowbug gamma-ray detection
  96. EP251130a: continued NOT optical observations indicate steep fading phase
  97. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  98. GRB 251202A: GOTO optical afterglow detection
  99. GRB 251126A: SVOM/VT optical observation
  100. EP251130a: SVOM/VT optical observation

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