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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').
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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"

37512 results found.

  1. GRB 251209A: Fermi GBM observation
  2. GRB 251205A: 1.3m DFOT optical upper limit
  3. GRB 251209A: AstroSat CZTI detection
  4. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  5. EP251124a: Mondy optical upper limit
  6. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  7. EP251130a: Mondy and AbAO optical observations
  8. GRB 251208A: AstroSat CZTI detection
  9. Fermi GBM Sub-Threshold Detection of GRB 251205A
  10. GRB 251208A: Glowbug gamma-ray detection
  11. GRB 251208B: COLIBRÍ optical upper limits
  12. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  13. GRB 251208C: GECAM-B observation of a short burst
  14. GRB 251208A: GECAM-B observation of a short burst
  15. Fermi GRB 251209A: Global MASTER-Net observations report
  16. Fermi GRB 251208C: Global MASTER-Net observations report
  17. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. GRB 251208B: Swift-XRT afterglow detection
  19. GRB 251208D: LAST optical upper limit
  20. GRB 251209A: Fermi GBM Final Real-time Localization
  21. GRB 251208D: LCO analysis of the XRT sources
  22. GRB 251208B: Fermi GBM Observation
  23. GRB 251208B: GROWTH-India Telescope optical upper limits
  24. GRB 251205A: J-band detection with WINTER
  25. GRB 251208D: Swift-XRT observations
  26. GRB 251208A: SVOM/GRM observation of a short burst
  27. GRB 251208C: SVOM/GRM observation of a short burst
  28. GRB 251129A: e-MERLIN C-band observations
  29. GRB 251205A: Liverpool Telescope further optical follow-up observations
  30. GRB 251208D: LCO optical upper limits
  31. GRB 251208B: Swift ToO observations
  32. GRB 251208B: Fermi-LAT detection
  33. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  34. GRB 251208D: SVOM possible detection of a faint burst
  35. GRB 251206A: SVOM detection of a burst through offline search
  36. GRB 251208C: Fermi GBM Final Real-time Localization
  37. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  38. GRB 251208B: Fermi GBM Final Real-time Localization
  39. GRB 251208A: Fermi GBM Final Real-time Localization
  40. GRB 251205A: FTW optical and NIR observations
  41. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  42. GRB 251205A: Liverpool Telescope further optical follow-up observations
  43. GRB 251205A: ZTF and ATLAS optical afterglow detections
  44. GRB 251205A: GROWTH-India Telescope optical observations
  45. GRB 251205A: Swift-BAT refined analysis
  46. GRB 251205A: Swift-XRT refined Analysis
  47. GRB 251205A: Swift/UVOT Detection
  48. GRB 251205A: Liverpool Telescope optical follow-up observations
  49. GRB 251203C: Swift/UVOT Upper Limit
  50. Konus-Wind detection of GRB 251118A
  51. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  52. GRB 251205A: COLIBRÍ optical observations
  53. GRB 251205A: GOTO optical afterglow detection
  54. GRB 251205A: NOT optical observations
  55. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  56. GRB 251205A: Enhanced Swift-XRT position
  57. Swift GRB 251205A : MASTER OT detection with host galaxy
  58. GRB 251205A: Swift detection of a burst with an optical afterglow
  59. GRB 251126B: Fermi GBM Final Localization
  60. GRB 251203A: Insight-HXMT/HE detection
  61. GRB 251203C: SVOM/ECLAIRs refined analysis
  62. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  63. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. GRB 251202A: SVOM/GRM observation
  65. GRB 251203A: GECAM-B observation of a burst
  66. GRB 251203A: SVOM/GRM observation
  67. GRB 251201B: SALT spectroscopic redshift z = 1.599
  68. GRB 251203C: J-band observations with WINTER
  69. GRB 251129B: Glowbug gamma-ray detection of a short burst
  70. GRB 251203A: AstroSat CZTI detection
  71. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  72. GRB 251203C: LCO optical afterglow confirmation
  73. GRB 251203C: SVOM/VT optical counterpart
  74. GRB 251203C: EP-FXT follow-up observation
  75. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  76. GRB 251129B: GECAM-B observation of a burst
  77. GRB 251203B: Swift-XRT observations
  78. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  79. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  80. GRB 251203C: LCO optical upper limits
  81. GRB 251203B: LCO optical upper limits
  82. GRB 251203B: SVOM/VT optical observation
  83. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  84. GRB 251203C: SVOM detection of a burst
  85. GRB 251203B: SVOM detection of a burst
  86. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  87. GRB 251201B: Insight-HXMT/HE detection
  88. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  89. GRB 251203A: Fermi GBM Final Real-time Localization
  90. EP251202a / GRB251202A: AstroSat CZTI detection
  91. GRB 251202A / EP251202a: SVOM/VT optical observation
  92. GRB 251201B: Fermi GBM Observation
  93. EP251202a/GRB 251202A: KAIT optical observations
  94. Fermi GRB 251202B: Global MASTER-Net observations report
  95. GRB 251202B: Fermi GBM Final Real-time Localization
  96. IPN triangulation of GRB 251129B (short/hard)
  97. GRB251129A/EP251129a: Swift UVOT detection
  98. GRB 251129B: AstroSat CZTI detection
  99. GRB 251202A: Fermi GBM Observation
  100. GRB 251202A: Swift/UVOT Detection

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