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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21770 results found.

  1. EP251212a: KAIT optical upper limit
  2. GRB 251209A: NuSTAR detection of prompt emission
  3. EP251212a : COLIBRÍ optical upper limit
  4. EP251212a: Einstein Probe detection of an X-ray transient
  5. IceCube-251210A: DDOTI Optical Upper Limit
  6. GRB 251205A: 1.3m DFOT optical upper limit
  7. GRB 251209A: AstroSat CZTI detection
  8. EP251124a: Mondy optical upper limit
  9. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  10. EP251130a: Mondy and AbAO optical observations
  11. GRB 251208B: COLIBRÍ optical upper limits
  12. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  13. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 251208B: Swift-XRT afterglow detection
  15. GRB 251208D: LAST optical upper limit
  16. GRB 251208D: LCO analysis of the XRT sources
  17. GRB 251208B: GROWTH-India Telescope optical upper limits
  18. GRB 251205A: J-band detection with WINTER
  19. GRB 251208A: SVOM/GRM observation of a short burst
  20. GRB 251208C: SVOM/GRM observation of a short burst
  21. GRB 251129A: e-MERLIN C-band observations
  22. GRB 251205A: Liverpool Telescope further optical follow-up observations
  23. GRB 251208D: LCO optical upper limits
  24. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  25. GRB 251206A: SVOM detection of a burst through offline search
  26. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  27. GRB 251205A: FTW optical and NIR observations
  28. GRB 251205A: Liverpool Telescope further optical follow-up observations
  29. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  30. GRB 251205A: ZTF and ATLAS optical afterglow detections
  31. GRB 251205A: GROWTH-India Telescope optical observations
  32. GRB 251205A: Swift/UVOT Detection
  33. GRB 251205A: Liverpool Telescope optical follow-up observations
  34. GRB 251203C: Swift/UVOT Upper Limit
  35. Konus-Wind detection of GRB 251118A
  36. GRB 251205A: COLIBRÍ optical observations
  37. GRB 251205A: NOT optical observations
  38. GRB 251205A: Enhanced Swift-XRT position
  39. Swift GRB 251205A : MASTER OT detection with host galaxy
  40. GRB 251205A: Swift detection of a burst with an optical afterglow
  41. GRB 251203A: Insight-HXMT/HE detection
  42. GRB 251203C: SVOM/ECLAIRs refined analysis
  43. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  44. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. GRB 251202A: SVOM/GRM observation
  46. GRB 251203A: SVOM/GRM observation
  47. GRB 251203C: J-band observations with WINTER
  48. GRB 251203C: SVOM/VT optical counterpart
  49. GRB 251203C: LCO optical upper limits
  50. GRB 251203B: LCO optical upper limits
  51. GRB 251203B: SVOM/VT optical observation
  52. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  53. GRB 251203B: SVOM detection of a burst
  54. EP251130a: MAO/AZT-22 optical observations
  55. EP251202a / GRB251202A: AstroSat CZTI detection
  56. EP251202a/GRB 251202A: KAIT optical observations
  57. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  58. IPN triangulation of GRB 251129B (short/hard)
  59. GRB251129A/EP251129a: Swift UVOT detection
  60. GRB 251202A: Swift/UVOT Detection
  61. GRB 251201B: Kilonova-Catcher optical afterglow detection
  62. GRB 251201B: Swift/UVOT Detection
  63. GRB 251201B: GECAM-B observation of a long burst
  64. EP251130a: continued NOT optical observations indicate steep fading phase
  65. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  66. GRB 251126A: SAO RAS optical marginal detection
  67. GRB 251202A: Swift-XRT afterglow detection
  68. EP251129a/GRB 251129A: NOWT Detection
  69. GRB 251126A: SVOM/VT optical observation
  70. EP251130a: SVOM/VT optical observation
  71. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  72. GRB 251201A: SVOM/GRM observation of a burst
  73. GRB 251201B: SVOM/VT optical fading
  74. Swift GRB 251201B : MASTER optical counterpart detection
  75. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  76. GRB 251201B: Enhanced Swift-XRT position
  77. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  78. GRB 251130B: AstroSat CZTI detection
  79. GRB 251201B: Swift detection of a burst with an optical counterpart
  80. EP251130a: Mondy optical observations
  81. EP251130a: Optical detections with Kinder observations
  82. EP251130a: SAO RAS optical observations
  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 251127A: SVOM/GRM observation
  87. EP251130a: COLIBRÍ optical counterpart candidate
  88. EP251130a: Einstein Probe detection of an X-ray transient
  89. GRB 251128A: AstroSat CZTI detection
  90. GRB 251129A / EP251129a: SAO RAS optical observations
  91. GRB 251126A: SAO RAS optical observations
  92. GRB 251128A: SVOM/GRM observation of a long burst
  93. SVOM GRB 251129A : MASTER optical counterpart detection
  94. GRB 251129A: Swift-XRT afterglow detection
  95. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  96. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  97. GRB 251129A: SVOM detection of a burst
  98. GRB 251129A: SVOM detection of a burst
  99. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  100. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst

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