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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"

26617 results found.

  1. GRB 251203B: Swift-XRT observations
  2. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  3. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  4. GRB 251203C: LCO optical upper limits
  5. GRB 251203B: LCO optical upper limits
  6. GRB 251203B: SVOM/VT optical observation
  7. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  8. GRB 251203C: SVOM detection of a burst
  9. SVOM GRB251203.77: Global MASTER-Net observations report
  10. SVOM GRB251203.76: Global MASTER-Net observations report
  11. GRB 251203B: SVOM detection of a burst
  12. GRB 251201B: Insight-HXMT/HE detection
  13. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  14. GRB 251203A: Fermi GBM Final Real-time Localization
  15. EP251202a / GRB251202A: AstroSat CZTI detection
  16. GRB 251202A / EP251202a: SVOM/VT optical observation
  17. GRB 251201B: Fermi GBM Observation
  18. EP251202a/GRB 251202A: KAIT optical observations
  19. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  20. Fermi GRB 251202B: Global MASTER-Net observations report
  21. GRB 251202B: Fermi GBM Final Real-time Localization
  22. GRB251129A/EP251129a: Swift UVOT detection
  23. GRB 251202A: Fermi GBM Observation
  24. GRB 251202A: Swift/UVOT Detection
  25. GRB 251201B: Kilonova-Catcher optical afterglow detection
  26. GRB 251201B: Swift/UVOT Detection
  27. GRB 251130B: Glowbug gamma-ray detection
  28. GRB 251201B: GECAM-B observation of a long burst
  29. EP251130a: continued NOT optical observations indicate steep fading phase
  30. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  31. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  32. GRB 251202A: GOTO optical afterglow detection
  33. GRB 251126A: SVOM/VT optical observation
  34. EP251130a: SVOM/VT optical observation
  35. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  36. Fermi GRB 251202A: Global MASTER-Net observations report
  37. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  38. GRB 251201B: Swift-XRT refined Analysis
  39. The EP-WXT trigger 01709249064: Las Cumbres discovery of the optical counterpart
  40. GRB 251202A: Fermi GBM Final Real-time Localization
  41. GRB 251201A: SVOM/GRM observation of a burst
  42. GRB 251201B: SVOM/VT optical fading
  43. Swift GRB 251201B : MASTER optical counterpart detection
  44. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  45. Swift GRB 251201B: Global MASTER-Net observations report
  46. GRB 251130B: AstroSat CZTI detection
  47. GRB 251201B: Swift detection of a burst with an optical counterpart
  48. GRB 251201B: Fermi GBM Final Real-time Localization
  49. EP251130a: Optical detections with Kinder observations
  50. SVOM GRB251201.19: Global MASTER-Net observations report
  51. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  52. EP251130A: Optical observation from 1.3m DFOT
  53. Fermi GRB 251130B: Global MASTER-Net observations report
  54. GRB 251127A: SVOM/GRM observation
  55. IceCube Alert 251130.75: Global MASTER-Net observations report
  56. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  57. EP251130a: Swift-XRT counterpart detection
  58. GRB 251130B: Fermi GBM Final Localization Correction
  59. EP251130a: Global MASTER-Net observations report
  60. GRB 251130B: Fermi GBM Final Real-time Localization
  61. EP251130a: COLIBRÍ optical counterpart candidate
  62. GRB 251130A: Fermi GBM Final Real-time Localization
  63. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  64. GRB 251128A: AstroSat CZTI detection
  65. GRB 251128A: GECAM-B detection
  66. GRB 251128A: SVOM/GRM observation of a long burst
  67. GRB 251128A: Insight-HXMT/HE detection
  68. SVOM GRB 251129A : MASTER optical counterpart detection
  69. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  70. Swift trigger 1418333 is not an astrophysical source
  71. GRB 251129A / EP251129a: SVOM/VT optical fading
  72. EP251129a: Global MASTER-Net observations report
  73. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  74. GRB 251128A: Fermi GBM Observation
  75. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  76. GRB 251129A: SVOM detection of a burst
  77. SVOM GRB251129A: Global MASTER-Net observations report
  78. GRB 251129A: SVOM detection of a burst
  79. GRB 251126A: Swift-BAT refined analysis
  80. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  81. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  82. Fermi GRB 251128A: Global MASTER-Net observations report
  83. GRB 251127A: Glowbug gamma-ray detection
  84. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  85. GRB 251126A NUTTelA-TAO Early Measurements
  86. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  87. GRB251126A: MAO/AZT-22 optical observations
  88. GRB 251128A: Fermi GBM Final Real-time Localization
  89. GRB251126A: Continued optical observation from 1.3m DFOT
  90. GRB 251126A: Swift/UVOT Detection
  91. GRB 251126A: Mondy and SAO RAS optical observations
  92. GRB 251126A: Swift-XRT refined Analysis
  93. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  94. GRB 251126A: NOT optical observations
  95. GRB 251126A: 1.3m DFOT optical afterglow detection
  96. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  97. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  98. GRB 251125B: GECAM-B detection
  99. Fermi GRB 251127A: Global MASTER-Net observations report
  100. GRB 251127A: Fermi GBM Final Real-time Localization

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