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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"

22855 results found.

  1. GRB 251129A: e-MERLIN C-band observations
  2. GRB 251205A: Liverpool Telescope further optical follow-up observations
  3. GRB 251208D: LCO optical upper limits
  4. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  5. GRB 251205A: Liverpool Telescope further optical follow-up observations
  6. GRB 251205A: GROWTH-India Telescope optical observations
  7. GRB 251205A: Swift/UVOT Detection
  8. GRB 251205A: Liverpool Telescope optical follow-up observations
  9. GRB 251203C: Swift/UVOT Upper Limit
  10. Konus-Wind detection of GRB 251118A
  11. GRB 251205A: COLIBRÍ optical observations
  12. GRB 251205A: NOT optical observations
  13. GRB 251205A: Enhanced Swift-XRT position
  14. Swift GRB 251205A : MASTER OT detection with host galaxy
  15. GRB 251205A: Swift detection of a burst with an optical afterglow
  16. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  17. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. GRB 251202A: SVOM/GRM observation
  19. GRB 251203A: GECAM-B observation of a burst
  20. GRB 251203A: SVOM/GRM observation
  21. GRB 251203C: J-band observations with WINTER
  22. GRB 251129B: Glowbug gamma-ray detection of a short burst
  23. GRB 251203A: AstroSat CZTI detection
  24. GRB 251203C: SVOM/VT optical counterpart
  25. GRB 251203B: Swift-XRT observations
  26. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  27. GRB 251203C: LCO optical upper limits
  28. GRB 251203B: LCO optical upper limits
  29. GRB 251203B: SVOM/VT optical observation
  30. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  31. GRB 251203B: SVOM detection of a burst
  32. EP251130a: MAO/AZT-22 optical observations
  33. EP251202a/GRB 251202A: KAIT optical observations
  34. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  35. IPN triangulation of GRB 251129B (short/hard)
  36. GRB251129A/EP251129a: Swift UVOT detection
  37. GRB 251202A: Swift/UVOT Detection
  38. GRB 251201B: Kilonova-Catcher optical afterglow detection
  39. GRB 251201B: Swift/UVOT Detection
  40. GRB 251130B: Glowbug gamma-ray detection
  41. EP251130a: continued NOT optical observations indicate steep fading phase
  42. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  43. GRB 251126A: SAO RAS optical marginal detection
  44. GRB 251202A: Swift-XRT afterglow detection
  45. EP251129a/GRB 251129A: NOWT Detection
  46. GRB 251126A: SVOM/VT optical observation
  47. EP251130a: SVOM/VT optical observation
  48. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  49. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  50. GRB 251201B: Swift-XRT refined Analysis
  51. GRB 251201A: SVOM/GRM observation of a burst
  52. GRB 251201B: SVOM/VT optical fading
  53. Swift GRB 251201B : MASTER optical counterpart detection
  54. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  55. GRB 251201B: Enhanced Swift-XRT position
  56. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  57. GRB 251130B: AstroSat CZTI detection
  58. GRB 251201B: Swift detection of a burst with an optical counterpart
  59. EP251130a: Mondy optical observations
  60. EP251130a: Optical detections with Kinder observations
  61. EP251130a: SAO RAS optical observations
  62. EP251130A: Optical observation from 1.3m DFOT
  63. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  64. EP251130a: JinShan optical observations
  65. GRB 251127A: SVOM/GRM observation
  66. EP251130a: Swift-XRT counterpart detection
  67. EP251130a: COLIBRÍ optical counterpart candidate
  68. EP251130a: Einstein Probe detection of an X-ray transient
  69. GRB 251129A / EP251129a: SAO RAS optical observations
  70. GRB 251126A: SAO RAS optical observations
  71. GRB 251128A: SVOM/GRM observation of a long burst
  72. SVOM GRB 251129A : MASTER optical counterpart detection
  73. GRB 251129A: Swift-XRT afterglow detection
  74. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  75. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  76. GRB 251129A: SVOM detection of a burst
  77. GRB 251129A: SVOM detection of a burst
  78. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  79. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  80. GRB 251127A: Glowbug gamma-ray detection
  81. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  82. GRB 251126A: further SAO RAS optical observations
  83. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  84. GRB251126A: MAO/AZT-22 optical observations
  85. GRB251126A: Continued optical observation from 1.3m DFOT
  86. GRB 251126A: Swift/UVOT Detection
  87. EP251124a: Pan-STARRS ri-band imaging and photometry
  88. GRB 251126A: Mondy and SAO RAS optical observations
  89. GRB 251126A: Swift-XRT refined Analysis
  90. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  91. GRB 251126A: 1.3m DFOT optical afterglow detection
  92. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  93. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  94. GRB 251126A: Enhanced Swift-XRT position
  95. GRB 251126A: Kilonova-Catcher optical afterglow detection
  96. GRB 251126A: Nanshan/HMT optical afterglow detection
  97. GRB 251126A: GIT discovery of the likely optical afterglow
  98. GRB 251126A: Swift detection of a burst
  99. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  100. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate

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