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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"

25778 results found.

  1. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  2. EP251130a: Mondy and AbAO optical observations
  3. Fermi GBM Sub-Threshold Detection of GRB 251205A
  4. GRB 251208A: Glowbug gamma-ray detection
  5. GRB 251208B: COLIBRÍ optical upper limits
  6. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  7. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. GRB 251208B: Swift-XRT afterglow detection
  9. GRB 251208D: LAST optical upper limit
  10. GRB 251208D: LCO analysis of the XRT sources
  11. GRB 251208B: Fermi GBM Observation
  12. GRB 251208B: GROWTH-India Telescope optical upper limits
  13. GRB 251205A: J-band detection with WINTER
  14. GRB 251208D: Swift-XRT observations
  15. GRB 251208A: SVOM/GRM observation of a short burst
  16. GRB 251208C: SVOM/GRM observation of a short burst
  17. GRB 251205A: Liverpool Telescope further optical follow-up observations
  18. GRB 251208D: LCO optical upper limits
  19. GRB 251208D: SVOM possible detection of a faint burst
  20. GRB 251206A: SVOM detection of a burst through offline search
  21. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  22. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  23. GRB 251205A: Liverpool Telescope further optical follow-up observations
  24. The EP-WXT trigger 01709249380 is likely a flaring star
  25. GRB 251205A: GROWTH-India Telescope optical observations
  26. GRB 251205A: Swift-XRT refined Analysis
  27. GRB 251205A: Swift/UVOT Detection
  28. GRB 251205A: Liverpool Telescope optical follow-up observations
  29. GRB 251203C: Swift/UVOT Upper Limit
  30. Konus-Wind detection of GRB 251118A
  31. GRB 251205A: COLIBRÍ optical observations
  32. GRB 251205A: NOT optical observations
  33. GRB 251205A: Enhanced Swift-XRT position
  34. Swift GRB 251205A : MASTER OT detection with host galaxy
  35. GRB 251205A: Swift detection of a burst with an optical afterglow
  36. GRB 251203C: SVOM/ECLAIRs refined analysis
  37. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  38. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  39. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  40. GRB 251202A: SVOM/GRM observation
  41. GRB 251203A: SVOM/GRM observation
  42. GRB 251201B: SALT spectroscopic redshift z = 1.599
  43. GRB 251203C: J-band observations with WINTER
  44. GRB 251129B: Glowbug gamma-ray detection of a short burst
  45. GRB 251203A: AstroSat CZTI detection
  46. GRB 251203C: SVOM/VT optical counterpart
  47. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  48. GRB 251203B: Swift-XRT observations
  49. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  50. GRB 251203C: LCO optical upper limits
  51. GRB 251203B: LCO optical upper limits
  52. GRB 251203B: SVOM/VT optical observation
  53. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  54. GRB 251203C: SVOM detection of a burst
  55. GRB 251203B: SVOM detection of a burst
  56. EP251130a: MAO/AZT-22 optical observations
  57. GRB 251201B: Fermi GBM Observation
  58. EP251202a/GRB 251202A: KAIT optical observations
  59. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  60. GRB 251202B: Fermi GBM Final Real-time Localization
  61. IPN triangulation of GRB 251129B (short/hard)
  62. GRB251129A/EP251129a: Swift UVOT detection
  63. GRB 251202A: Fermi GBM Observation
  64. GRB 251202A: Swift/UVOT Detection
  65. GRB 251201B: Kilonova-Catcher optical afterglow detection
  66. GRB 251201B: Swift/UVOT Detection
  67. GRB 251130B: Glowbug gamma-ray detection
  68. EP251130a: continued NOT optical observations indicate steep fading phase
  69. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  70. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  71. GRB 251126A: SAO RAS optical marginal detection
  72. GRB 251202A: Swift-XRT afterglow detection
  73. EP251129a/GRB 251129A: NOWT Detection
  74. GRB 251126A: SVOM/VT optical observation
  75. EP251130a: SVOM/VT optical observation
  76. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  77. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  78. GRB 251201B: Swift-XRT refined Analysis
  79. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  80. GRB 251202A: Fermi GBM Final Real-time Localization
  81. GRB 251201A: SVOM/GRM observation of a burst
  82. GRB 251201B: SVOM/VT optical fading
  83. Swift GRB 251201B : MASTER optical counterpart detection
  84. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  85. GRB 251201B: Enhanced Swift-XRT position
  86. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  87. GRB 251130B: AstroSat CZTI detection
  88. GRB 251201B: Swift detection of a burst with an optical counterpart
  89. EP251130a: Mondy optical observations
  90. EP251130a: Optical detections with Kinder observations
  91. EP251130a: SAO RAS optical observations
  92. EP251130A: Optical observation from 1.3m DFOT
  93. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  94. EP251130a: JinShan optical observations
  95. GRB 251127A: SVOM/GRM observation
  96. EP251130a: Swift-XRT counterpart detection
  97. EP251130a: COLIBRÍ optical counterpart candidate
  98. EP251130a: Einstein Probe detection of an X-ray transient
  99. EP251129a/GRB 251129A: EP-FXT follow-up observations
  100. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460

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