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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"

28088 results found.

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

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