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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"

35335 results found.

  1. GRB 251203A: AstroSat CZTI detection
  2. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  3. GRB 251203C: LCO optical afterglow confirmation
  4. GRB 251203C: SVOM/VT optical counterpart
  5. GRB 251203C: EP-FXT follow-up observation
  6. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  7. GRB 251129B: GECAM-B observation of a burst
  8. GRB 251203B: Swift-XRT observations
  9. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  10. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  11. GRB 251203C: LCO optical upper limits
  12. GRB 251203B: LCO optical upper limits
  13. GRB 251203B: SVOM/VT optical observation
  14. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  15. GRB 251203C: SVOM detection of a burst
  16. GRB 251203B: SVOM detection of a burst
  17. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  18. GRB 251201B: Insight-HXMT/HE detection
  19. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  20. GRB 251203A: Fermi GBM Final Real-time Localization
  21. EP251202a / GRB251202A: AstroSat CZTI detection
  22. GRB 251202A / EP251202a: SVOM/VT optical observation
  23. GRB 251201B: Fermi GBM Observation
  24. EP251202a/GRB 251202A: KAIT optical observations
  25. Fermi GRB 251202B: Global MASTER-Net observations report
  26. GRB 251202B: Fermi GBM Final Real-time Localization
  27. IPN triangulation of GRB 251129B (short/hard)
  28. GRB251129A/EP251129a: Swift UVOT detection
  29. GRB 251129B: AstroSat CZTI detection
  30. GRB 251202A: Fermi GBM Observation
  31. GRB 251202A: Swift/UVOT Detection
  32. GRB 251201B: Kilonova-Catcher optical afterglow detection
  33. GRB 251201B: Swift/UVOT Detection
  34. GRB 251130B: Glowbug gamma-ray detection
  35. GRB 251201B: GECAM-B observation of a long burst
  36. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  37. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  38. GRB 251202A: GOTO optical afterglow detection
  39. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  40. GRB 251201A: GECAM-B observation of a burst
  41. GRB 251126A: SAO RAS optical marginal detection
  42. GRB 251202A: Swift-XRT afterglow detection
  43. EP251129a/GRB 251129A: NOWT Detection
  44. GRB 251126A: SVOM/VT optical observation
  45. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  46. Fermi GRB 251202A: Global MASTER-Net observations report
  47. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  48. GRB 251201B: Swift-XRT refined Analysis
  49. GRB 251202A: Fermi GBM Final Real-time Localization
  50. GRB 251201A: SVOM/GRM observation of a burst
  51. GRB 251201B: SVOM/VT optical fading
  52. Swift GRB 251201B : MASTER optical counterpart detection
  53. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  54. Swift GRB 251201B: Global MASTER-Net observations report
  55. GRB 251201B: Enhanced Swift-XRT position
  56. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  57. GRB 251130B: AstroSat CZTI detection
  58. GRB 251201B: Swift detection of a burst with an optical counterpart
  59. GRB 251201B: Fermi GBM Final Real-time Localization
  60. EP251130a: Mondy optical observations
  61. EP251130a: SAO RAS optical observations
  62. EP251130a: KAIT optical observations
  63. GRB 251201A: MAXI/GSC detection
  64. Fermi GRB 251130B: Global MASTER-Net observations report
  65. GRB 251127A: SVOM/GRM observation
  66. GRB 251130B: Fermi GBM Final Localization Correction
  67. GRB 251130B: Fermi GBM Final Real-time Localization
  68. EP251129a/GRB 251129A: EP-FXT follow-up observations
  69. GRB 251130A: Fermi GBM Final Real-time Localization
  70. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  71. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  72. GRB 251128A: AstroSat CZTI detection
  73. GRB 251129A / EP251129a: SAO RAS optical observations
  74. GRB 251126A: SAO RAS optical observations
  75. GRB 251128A: GECAM-B detection
  76. GRB 251128A: SVOM/GRM observation of a long burst
  77. GRB 251128A: Insight-HXMT/HE detection
  78. SVOM GRB 251129A : MASTER optical counterpart detection
  79. GRB 251129A: Swift-XRT afterglow detection
  80. GRB 251129A: Swift ToO observations
  81. GRB 251129A / EP251129a: SVOM/VT optical fading
  82. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  83. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  84. GRB 251129A: Correction to the position of the optical counterpar
  85. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  86. GRB 251128A: Fermi GBM Observation
  87. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  88. GRB 251129A: SVOM detection of a burst
  89. GRB 251129A: SVOM detection of a burst
  90. GRB 251126A: Swift-BAT refined analysis
  91. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  92. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  93. Fermi GRB 251128A: Global MASTER-Net observations report
  94. GRB 251127A: Glowbug gamma-ray detection
  95. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  96. GRB 251126A: further SAO RAS optical observations
  97. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  98. GRB 251126A NUTTelA-TAO Early Measurements
  99. GRB251126A: MAO/AZT-22 optical observations
  100. GRB 251128A: Fermi GBM Final Real-time Localization

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