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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"

42600 results found.

  1. GRB 251208B: Fermi GBM Observation
  2. GRB 251208B: GROWTH-India Telescope optical upper limits
  3. GRB 251205A: J-band detection with WINTER
  4. GRB 251208D: Swift-XRT observations
  5. GRB 251208A: SVOM/GRM observation of a short burst
  6. GRB 251208C: SVOM/GRM observation of a short burst
  7. GRB 251129A: e-MERLIN C-band observations
  8. LAT GRB251208.43: Global MASTER-Net observations report
  9. GRB 251205A: Liverpool Telescope further optical follow-up observations
  10. GRB 251208D: LCO optical upper limits
  11. SVOM GRB251208D: Global MASTER-Net observations report
  12. GRB 251208B: Swift ToO observations
  13. GRB 251208B: Fermi-LAT detection
  14. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  15. GRB 251208D: SVOM possible detection of a faint burst
  16. GRB 251206A: SVOM detection of a burst through offline search
  17. GRB 251208C: Fermi GBM Final Real-time Localization
  18. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  19. GRB 251208B: Fermi GBM Final Real-time Localization
  20. GRB 251208A: Fermi GBM Final Real-time Localization
  21. GRB 251205A: FTW optical and NIR observations
  22. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  23. GRB 251205A: Liverpool Telescope further optical follow-up observations
  24. SVOM GRB251206.86: Global MASTER-Net observations report
  25. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  26. The EP-WXT trigger 01709249380 is likely a flaring star
  27. GRB 251205A: ZTF and ATLAS optical afterglow detections
  28. GRB 251205A: GROWTH-India Telescope optical observations
  29. GRB 251205A: Swift-BAT refined analysis
  30. GRB 251205A: Swift-XRT refined Analysis
  31. GRB 251205A: Swift/UVOT Detection
  32. GRB 251205A: Liverpool Telescope optical follow-up observations
  33. Konus-Wind detection of GRB 251118A
  34. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  35. GRB 251205A: COLIBRÍ optical observations
  36. GRB 251205A: GOTO optical afterglow detection
  37. GRB 251205A: NOT optical observations
  38. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  39. GRB 251205A: Enhanced Swift-XRT position
  40. Swift GRB 251205A : MASTER OT detection with host galaxy
  41. GRB 251205A: Swift detection of a burst with an optical afterglow
  42. Swift GRB251205A: Global MASTER-Net observations report
  43. GRB 251126B: Fermi GBM Final Localization
  44. GRB 251203A: Insight-HXMT/HE detection
  45. GRB 251203C: SVOM/ECLAIRs refined analysis
  46. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  47. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  48. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. GRB 251202A: SVOM/GRM observation
  50. GRB 251203A: GECAM-B observation of a burst
  51. GRB 251203A: SVOM/GRM observation
  52. GRB 251201B: SALT spectroscopic redshift z = 1.599
  53. GRB 251203C: J-band observations with WINTER
  54. GRB 251129B: Glowbug gamma-ray detection of a short burst
  55. GRB 251203A: AstroSat CZTI detection
  56. EP251130a: JinShan near-infrared observations
  57. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  58. GRB 251203C: LCO optical afterglow confirmation
  59. GRB 251203C: SVOM/VT optical counterpart
  60. GRB 251203C: EP-FXT follow-up observation
  61. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  62. GRB 251129B: GECAM-B observation of a burst
  63. GRB 251203B: Swift-XRT observations
  64. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  65. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  66. GRB 251203C: LCO optical upper limits
  67. GRB 251203B: LCO optical upper limits
  68. GRB 251203B: SVOM/VT optical observation
  69. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  70. GRB 251203C: SVOM detection of a burst
  71. SVOM GRB251203.77: Global MASTER-Net observations report
  72. SVOM GRB251203B: Global MASTER-Net observations report
  73. GRB 251203B: SVOM detection of a burst
  74. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  75. GRB 251201B: Insight-HXMT/HE detection
  76. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  77. EP251130a: MAO/AZT-22 optical observations
  78. GRB 251203A: Fermi GBM Final Real-time Localization
  79. EP251202a / GRB251202A: AstroSat CZTI detection
  80. GRB 251202A / EP251202a: SVOM/VT optical observation
  81. GRB 251201B: Fermi GBM Observation
  82. EP251202a/GRB 251202A: KAIT optical observations
  83. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  84. Fermi GRB 251202B: Global MASTER-Net observations report
  85. GRB 251202B: Fermi GBM Final Real-time Localization
  86. IPN triangulation of GRB 251129B (short/hard)
  87. GRB 251129B: AstroSat CZTI detection
  88. GRB 251202A: Fermi GBM Observation
  89. GRB 251202A: Swift/UVOT Detection
  90. GRB 251201B: Kilonova-Catcher optical afterglow detection
  91. GRB 251201B: Swift/UVOT Detection
  92. GRB 251130B: Glowbug gamma-ray detection
  93. GRB 251201B: GECAM-B observation of a long burst
  94. EP251130a: continued NOT optical observations indicate steep fading phase
  95. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  96. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  97. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  98. GRB 251202A: GOTO optical afterglow detection
  99. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  100. GRB 251201A: GECAM-B observation of a burst

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