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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"

27774 results found.

  1. GRB 251205A: GOTO optical afterglow detection
  2. GRB 251205A: Enhanced Swift-XRT position
  3. Swift GRB 251205A : MASTER OT detection with host galaxy
  4. GRB 251205A: Swift detection of a burst with an optical afterglow
  5. Swift GRB251205A: Global MASTER-Net observations report
  6. GRB 251126B: Fermi GBM Final Localization
  7. GRB 251203A: Insight-HXMT/HE detection
  8. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  9. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  10. GRB 251202A: SVOM/GRM observation
  11. GRB 251201B: SALT spectroscopic redshift z = 1.599
  12. GRB 251129B: Glowbug gamma-ray detection of a short burst
  13. GRB 251203A: AstroSat CZTI detection
  14. GRB 251203B: Swift-XRT observations
  15. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  16. GRB 251203B: LCO optical upper limits
  17. GRB 251203C: SVOM detection of a burst
  18. GRB 251203B: SVOM detection of a burst
  19. GRB 251201B: Insight-HXMT/HE detection
  20. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  21. EP251130a: MAO/AZT-22 optical observations
  22. GRB 251203A: Fermi GBM Final Real-time Localization
  23. EP251202a / GRB251202A: AstroSat CZTI detection
  24. GRB 251202A / EP251202a: SVOM/VT optical observation
  25. GRB 251201B: Fermi GBM Observation
  26. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  27. GRB 251202B: Fermi GBM Final Real-time Localization
  28. IPN triangulation of GRB 251129B (short/hard)
  29. GRB251129A/EP251129a: Swift UVOT detection
  30. GRB 251129B: AstroSat CZTI detection
  31. GRB 251202A: Fermi GBM Observation
  32. GRB 251202A: Swift/UVOT Detection
  33. GRB 251201B: Kilonova-Catcher optical afterglow detection
  34. GRB 251201B: Swift/UVOT Detection
  35. GRB 251130B: Glowbug gamma-ray detection
  36. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  37. GRB 251202A: GOTO optical afterglow detection
  38. GRB 251126A: SAO RAS optical marginal detection
  39. GRB 251202A: Swift-XRT afterglow detection
  40. EP251129a/GRB 251129A: NOWT Detection
  41. GRB 251126A: SVOM/VT optical observation
  42. EP251130a: SVOM/VT optical observation
  43. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  44. GRB 251201B: Swift-XRT refined Analysis
  45. GRB 251202A: Fermi GBM Final Real-time Localization
  46. GRB 251201B: SVOM/VT optical fading
  47. Swift GRB 251201B : MASTER optical counterpart detection
  48. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  49. Swift GRB 251201B: Global MASTER-Net observations report
  50. GRB 251201B: Enhanced Swift-XRT position
  51. GRB 251130B: AstroSat CZTI detection
  52. GRB 251201B: Swift detection of a burst with an optical counterpart
  53. GRB 251201B: Fermi GBM Final Real-time Localization
  54. EP251130a: Mondy optical observations
  55. EP251130a: Optical detections with Kinder observations
  56. EP251130a: SAO RAS optical observations
  57. EP251130A: Optical observation from 1.3m DFOT
  58. GRB 251201A: MAXI/GSC detection
  59. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  60. EP251130a: Swift-XRT counterpart detection
  61. GRB 251130B: Fermi GBM Final Localization Correction
  62. GRB 251130B: Fermi GBM Final Real-time Localization
  63. EP251130a: Einstein Probe detection of an X-ray transient
  64. GRB 251130A: Fermi GBM Final Real-time Localization
  65. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  66. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  67. GRB 251128A: AstroSat CZTI detection
  68. GRB 251129A / EP251129a: SAO RAS optical observations
  69. GRB 251126A: SAO RAS optical observations
  70. GRB 251128A: GECAM-B detection
  71. GRB 251128A: Insight-HXMT/HE detection
  72. SVOM GRB 251129A : MASTER optical counterpart detection
  73. GRB 251129A: Swift-XRT afterglow detection
  74. Swift trigger 1418333 is not an astrophysical source
  75. GRB 251129A: Swift ToO observations
  76. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  77. GRB 251128A: Fermi GBM Observation
  78. GRB 251129A: SVOM detection of a burst
  79. GRB 251129A: SVOM detection of a burst
  80. GRB 251126A: Swift-BAT refined analysis
  81. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  82. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 251127A: Glowbug gamma-ray detection
  84. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  85. GRB 251126A: further SAO RAS optical observations
  86. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  87. GRB 251126A NUTTelA-TAO Early Measurements
  88. GRB251126A: MAO/AZT-22 optical observations
  89. GRB 251128A: Fermi GBM Final Real-time Localization
  90. GRB251126A: Continued optical observation from 1.3m DFOT
  91. GRB 251126A: Swift/UVOT Detection
  92. EP251124a: Pan-STARRS ri-band imaging and photometry
  93. GRB 251126A: Mondy and SAO RAS optical observations
  94. GRB 251126A: Swift-XRT refined Analysis
  95. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  96. GRB 251126A: NOT optical observations
  97. GRB 251126A: 1.3m DFOT optical afterglow detection
  98. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  99. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  100. GRB 251125B: GECAM-B detection

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