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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"

28083 results found.

  1. GRB 251208A: SVOM/GRM observation of a short burst
  2. GRB 251208C: SVOM/GRM observation of a short burst
  3. GRB 251129A: e-MERLIN C-band observations
  4. LAT GRB251208.43: Global MASTER-Net observations report
  5. GRB 251205A: Liverpool Telescope further optical follow-up observations
  6. GRB 251208D: LCO optical upper limits
  7. SVOM GRB251208D: Global MASTER-Net observations report
  8. GRB 251208B: Fermi-LAT detection
  9. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  10. GRB 251208D: SVOM possible detection of a faint burst
  11. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  12. GRB 251205A: Liverpool Telescope further optical follow-up observations
  13. SVOM GRB251206.86: Global MASTER-Net observations report
  14. GRB 251205A: GROWTH-India Telescope optical observations
  15. GRB 251205A: Swift-BAT refined analysis
  16. GRB 251205A: Swift-XRT refined Analysis
  17. GRB 251205A: Swift/UVOT Detection
  18. GRB 251205A: Liverpool Telescope optical follow-up observations
  19. GRB 251203C: Swift/UVOT Upper Limit
  20. GRB 251205A: COLIBRÍ optical observations
  21. GRB 251205A: NOT optical observations
  22. GRB 251205A: Enhanced Swift-XRT position
  23. Swift GRB 251205A : MASTER OT detection with host galaxy
  24. GRB 251205A: Swift detection of a burst with an optical afterglow
  25. Swift GRB251205A: Global MASTER-Net observations report
  26. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  27. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  28. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 251202A: SVOM/GRM observation
  30. GRB 251203A: GECAM-B observation of a burst
  31. GRB 251203A: SVOM/GRM observation
  32. GRB 251203C: J-band observations with WINTER
  33. GRB 251129B: Glowbug gamma-ray detection of a short burst
  34. GRB 251203A: AstroSat CZTI detection
  35. GRB 251203C: SVOM/VT optical counterpart
  36. GRB 251203C: EP-FXT follow-up observation
  37. GRB 251203B: Swift-XRT observations
  38. GRB 251203C: LCO optical upper limits
  39. GRB 251203B: LCO optical upper limits
  40. GRB 251203B: SVOM/VT optical observation
  41. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  42. SVOM GRB251203.77: Global MASTER-Net observations report
  43. SVOM GRB251203B: Global MASTER-Net observations report
  44. GRB 251203B: SVOM detection of a burst
  45. EP251130a: MAO/AZT-22 optical observations
  46. GRB 251201B: Fermi GBM Observation
  47. EP251202a/GRB 251202A: KAIT optical observations
  48. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  49. Fermi GRB 251202B: Global MASTER-Net observations report
  50. IPN triangulation of GRB 251129B (short/hard)
  51. GRB251129A/EP251129a: Swift UVOT detection
  52. GRB 251202A: Fermi GBM Observation
  53. GRB 251202A: Swift/UVOT Detection
  54. GRB 251201B: Kilonova-Catcher optical afterglow detection
  55. GRB 251201B: Swift/UVOT Detection
  56. GRB 251130B: Glowbug gamma-ray detection
  57. EP251130a: continued NOT optical observations indicate steep fading phase
  58. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  59. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  60. GRB 251126A: SAO RAS optical marginal detection
  61. GRB 251202A: Swift-XRT afterglow detection
  62. EP251129a/GRB 251129A: NOWT Detection
  63. GRB 251126A: SVOM/VT optical observation
  64. EP251130a: SVOM/VT optical observation
  65. Fermi GRB 251202A: Global MASTER-Net observations report
  66. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  67. GRB 251201B: Swift-XRT refined Analysis
  68. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 251201A: SVOM/GRM observation of a burst
  70. GRB 251201B: SVOM/VT optical fading
  71. Swift GRB 251201B : MASTER optical counterpart detection
  72. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  73. Swift GRB 251201B: Global MASTER-Net observations report
  74. GRB 251201B: Enhanced Swift-XRT position
  75. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  76. GRB 251201B: Swift detection of a burst with an optical counterpart
  77. GRB 251201B: Fermi GBM Final Real-time Localization
  78. EP251130a: Mondy optical observations
  79. EP251130a: Optical detections with Kinder observations
  80. SVOM GRB251201.19: Global MASTER-Net observations report
  81. EP251130a: SAO RAS optical observations
  82. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  83. EP251130A: Optical observation from 1.3m DFOT
  84. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP251130a: JinShan optical observations
  86. GRB 251201A: MAXI/GSC detection
  87. Fermi GRB 251130B: Global MASTER-Net observations report
  88. GRB 251127A: SVOM/GRM observation
  89. IceCube Alert 251130.75: Global MASTER-Net observations report
  90. EP251130a: Swift-XRT counterpart detection
  91. EP251130a: Global MASTER-Net observations report
  92. EP251130a: COLIBRÍ optical counterpart candidate
  93. EP251130a: Einstein Probe detection of an X-ray transient
  94. GRB 251129A / EP251129a: SAO RAS optical observations
  95. GRB 251126A: SAO RAS optical observations
  96. GRB 251128A: SVOM/GRM observation of a long burst
  97. SVOM GRB 251129A : MASTER optical counterpart detection
  98. GRB 251129A: Swift-XRT afterglow detection
  99. EP251129a: Global MASTER-Net observations report
  100. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient

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