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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"

45401 results found.

  1. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  2. GRB 251208D: SVOM possible detection of a faint burst
  3. GRB 251206A: SVOM detection of a burst through offline search
  4. GRB 251208C: Fermi GBM Final Real-time Localization
  5. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  6. GRB 251208B: Fermi GBM Final Real-time Localization
  7. GRB 251208A: Fermi GBM Final Real-time Localization
  8. GRB 251205A: FTW optical and NIR observations
  9. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  10. GRB 251205A: Liverpool Telescope further optical follow-up observations
  11. SVOM GRB251206.86: Global MASTER-Net observations report
  12. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  13. The EP-WXT trigger 01709249380 is likely a flaring star
  14. GRB 251205A: ZTF and ATLAS optical afterglow detections
  15. GRB 251205A: GROWTH-India Telescope optical observations
  16. GRB 251205A: Swift-BAT refined analysis
  17. GRB 251205A: Swift-XRT refined Analysis
  18. GRB 251205A: Swift/UVOT Detection
  19. GRB 251205A: Liverpool Telescope optical follow-up observations
  20. GRB 251203C: Swift/UVOT Upper Limit
  21. Konus-Wind detection of GRB 251118A
  22. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  23. GRB 251205A: COLIBRÍ optical observations
  24. GRB 251205A: GOTO optical afterglow detection
  25. GRB 251205A: NOT optical observations
  26. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  27. GRB 251205A: Enhanced Swift-XRT position
  28. Swift GRB 251205A : MASTER OT detection with host galaxy
  29. GRB 251205A: Swift detection of a burst with an optical afterglow
  30. Swift GRB251205A: Global MASTER-Net observations report
  31. GRB 251126B: Fermi GBM Final Localization
  32. GRB 251203A: Insight-HXMT/HE detection
  33. GRB 251203C: SVOM/ECLAIRs refined analysis
  34. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  35. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  36. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 251202A: SVOM/GRM observation
  38. GRB 251203A: GECAM-B observation of a burst
  39. GRB 251203A: SVOM/GRM observation
  40. GRB 251201B: SALT spectroscopic redshift z = 1.599
  41. GRB 251203C: J-band observations with WINTER
  42. GRB 251129B: Glowbug gamma-ray detection of a short burst
  43. GRB 251203A: AstroSat CZTI detection
  44. EP251130a: JinShan near-infrared observations
  45. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  46. GRB 251203C: LCO optical afterglow confirmation
  47. GRB 251203C: SVOM/VT optical counterpart
  48. GRB 251203C: EP-FXT follow-up observation
  49. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  50. GRB 251129B: GECAM-B observation of a burst
  51. GRB 251203B: Swift-XRT observations
  52. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  53. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  54. GRB 251203C: LCO optical upper limits
  55. GRB 251203B: LCO optical upper limits
  56. GRB 251203B: SVOM/VT optical observation
  57. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  58. GRB 251203C: SVOM detection of a burst
  59. SVOM GRB251203.77: Global MASTER-Net observations report
  60. SVOM GRB251203B: Global MASTER-Net observations report
  61. GRB 251203B: SVOM detection of a burst
  62. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  63. GRB 251201B: Insight-HXMT/HE detection
  64. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  65. EP251130a: MAO/AZT-22 optical observations
  66. GRB 251203A: Fermi GBM Final Real-time Localization
  67. EP251202a / GRB251202A: AstroSat CZTI detection
  68. GRB 251202A / EP251202a: SVOM/VT optical observation
  69. GRB 251201B: Fermi GBM Observation
  70. EP251202a/GRB 251202A: KAIT optical observations
  71. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  72. Fermi GRB 251202B: Global MASTER-Net observations report
  73. GRB 251202B: Fermi GBM Final Real-time Localization
  74. IPN triangulation of GRB 251129B (short/hard)
  75. GRB251129A/EP251129a: Swift UVOT detection
  76. GRB 251129B: AstroSat CZTI detection
  77. GRB 251202A: Fermi GBM Observation
  78. GRB 251202A: Swift/UVOT Detection
  79. GRB 251201B: Kilonova-Catcher optical afterglow detection
  80. GRB 251201B: Swift/UVOT Detection
  81. GRB 251130B: Glowbug gamma-ray detection
  82. GRB 251201B: GECAM-B observation of a long burst
  83. EP251130a: continued NOT optical observations indicate steep fading phase
  84. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  85. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  86. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  87. GRB 251202A: GOTO optical afterglow detection
  88. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  89. GRB 251201A: GECAM-B observation of a burst
  90. GRB 251126A: SAO RAS optical marginal detection
  91. GRB 251202A: Swift-XRT afterglow detection
  92. EP251129a/GRB 251129A: NOWT Detection
  93. GRB 251126A: SVOM/VT optical observation
  94. EP251130a: SVOM/VT optical observation
  95. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  96. Fermi GRB 251202A: Global MASTER-Net observations report
  97. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  98. GRB 251201B: Swift-XRT refined Analysis
  99. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  100. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart

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