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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"

21786 results found.

  1. GRB 251203B: AbAO optical observations
  2. GRB 251213A: SVOM/GRM observation
  3. EP251214a: KAIT optical upper limit
  4. GRB 251214A: AstroSat CZTI detection
  5. GRB 251214B: Swift/UVOT Detection
  6. GRB 251214B: COLIBRÍ observations of the afterglow
  7. EP251214a: EP-FXT non-detection and upper limit
  8. GRB 251214B: 1.3m DFOT optical detection
  9. GRB 251214B: Enhanced Swift-XRT position
  10. GRB 251214B: Xinglong-2.16m optical observation
  11. GRB 251214B : MASTER optical afterglow detection
  12. GRB 251214B: SVOM/C-GFT optical observations
  13. EP251214a: COLIBRÍ optical upper limit
  14. EP251214.305: COLIBRÍ optical upper limit
  15. GRB 251214B: Swift detection of a burst with an optical counterpart
  16. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  17. EP251212a: KAIT optical upper limit
  18. GRB 251209A: NuSTAR detection of prompt emission
  19. EP251212a : COLIBRÍ optical upper limit
  20. EP251212a: Einstein Probe detection of an X-ray transient
  21. IceCube-251210A: DDOTI Optical Upper Limit
  22. GRB 251205A: 1.3m DFOT optical upper limit
  23. GRB 251209A: AstroSat CZTI detection
  24. EP251124a: Mondy optical upper limit
  25. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  26. EP251130a: Mondy and AbAO optical observations
  27. GRB 251208B: COLIBRÍ optical upper limits
  28. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  29. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. GRB 251208B: Swift-XRT afterglow detection
  31. GRB 251208D: LAST optical upper limit
  32. GRB 251208D: LCO analysis of the XRT sources
  33. GRB 251208B: GROWTH-India Telescope optical upper limits
  34. GRB 251205A: J-band detection with WINTER
  35. GRB 251208A: SVOM/GRM observation of a short burst
  36. GRB 251208C: SVOM/GRM observation of a short burst
  37. GRB 251129A: e-MERLIN C-band observations
  38. GRB 251205A: Liverpool Telescope further optical follow-up observations
  39. GRB 251208D: LCO optical upper limits
  40. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  41. GRB 251206A: SVOM detection of a burst through offline search
  42. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  43. GRB 251205A: FTW optical and NIR observations
  44. GRB 251205A: Liverpool Telescope further optical follow-up observations
  45. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  46. GRB 251205A: ZTF and ATLAS optical afterglow detections
  47. GRB 251205A: GROWTH-India Telescope optical observations
  48. GRB 251205A: Swift/UVOT Detection
  49. GRB 251205A: Liverpool Telescope optical follow-up observations
  50. GRB 251203C: Swift/UVOT Upper Limit
  51. Konus-Wind detection of GRB 251118A
  52. GRB 251205A: COLIBRÍ optical observations
  53. GRB 251205A: NOT optical observations
  54. GRB 251205A: Enhanced Swift-XRT position
  55. Swift GRB 251205A : MASTER OT detection with host galaxy
  56. GRB 251205A: Swift detection of a burst with an optical afterglow
  57. GRB 251203A: Insight-HXMT/HE detection
  58. GRB 251203C: SVOM/ECLAIRs refined analysis
  59. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  60. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 251202A: SVOM/GRM observation
  62. GRB 251203A: SVOM/GRM observation
  63. GRB 251203C: J-band observations with WINTER
  64. GRB 251203C: SVOM/VT optical counterpart
  65. GRB 251203C: LCO optical upper limits
  66. GRB 251203B: LCO optical upper limits
  67. GRB 251203B: SVOM/VT optical observation
  68. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  69. GRB 251203B: SVOM detection of a burst
  70. EP251130a: MAO/AZT-22 optical observations
  71. EP251202a / GRB251202A: AstroSat CZTI detection
  72. EP251202a/GRB 251202A: KAIT optical observations
  73. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  74. IPN triangulation of GRB 251129B (short/hard)
  75. GRB251129A/EP251129a: Swift UVOT detection
  76. GRB 251202A: Swift/UVOT Detection
  77. GRB 251201B: Kilonova-Catcher optical afterglow detection
  78. GRB 251201B: Swift/UVOT Detection
  79. GRB 251201B: GECAM-B observation of a long burst
  80. EP251130a: continued NOT optical observations indicate steep fading phase
  81. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  82. GRB 251126A: SAO RAS optical marginal detection
  83. GRB 251202A: Swift-XRT afterglow detection
  84. EP251129a/GRB 251129A: NOWT Detection
  85. GRB 251126A: SVOM/VT optical observation
  86. EP251130a: SVOM/VT optical observation
  87. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  88. GRB 251201A: SVOM/GRM observation of a burst
  89. GRB 251201B: SVOM/VT optical fading
  90. Swift GRB 251201B : MASTER optical counterpart detection
  91. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  92. GRB 251201B: Enhanced Swift-XRT position
  93. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  94. GRB 251130B: AstroSat CZTI detection
  95. GRB 251201B: Swift detection of a burst with an optical counterpart
  96. EP251130a: Mondy optical observations
  97. EP251130a: Optical detections with Kinder observations
  98. EP251130a: SAO RAS optical observations
  99. EP251130A: Optical observation from 1.3m DFOT
  100. EP251130a: refined analysis of the EP-WXT and EP-FXT observations

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