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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"

25655 results found.

  1. GRB 251203B: LCO optical upper limits
  2. GRB 251203B: SVOM/VT optical observation
  3. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  4. GRB 251203C: SVOM detection of a burst
  5. SVOM GRB251203.77: Global MASTER-Net observations report
  6. SVOM GRB251203B: Global MASTER-Net observations report
  7. GRB 251203B: SVOM detection of a burst
  8. GRB 251203A: Fermi GBM Final Real-time Localization
  9. GRB 251202A / EP251202a: SVOM/VT optical observation
  10. GRB 251201B: Fermi GBM Observation
  11. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  12. Fermi GRB 251202B: Global MASTER-Net observations report
  13. GRB 251202B: Fermi GBM Final Real-time Localization
  14. IPN triangulation of GRB 251129B (short/hard)
  15. GRB251129A/EP251129a: Swift UVOT detection
  16. GRB 251202A: Fermi GBM Observation
  17. GRB 251202A: Swift/UVOT Detection
  18. GRB 251201B: Kilonova-Catcher optical afterglow detection
  19. GRB 251201B: Swift/UVOT Detection
  20. GRB 251130B: Glowbug gamma-ray detection
  21. EP251130a: continued NOT optical observations indicate steep fading phase
  22. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  23. GRB 251202A: GOTO optical afterglow detection
  24. GRB 251126A: SVOM/VT optical observation
  25. EP251130a: SVOM/VT optical observation
  26. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  27. Fermi GRB 251202A: Global MASTER-Net observations report
  28. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  29. GRB 251201B: Swift-XRT refined Analysis
  30. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  31. GRB 251202A: Fermi GBM Final Real-time Localization
  32. GRB 251201A: SVOM/GRM observation of a burst
  33. GRB 251201B: SVOM/VT optical fading
  34. Swift GRB 251201B : MASTER optical counterpart detection
  35. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  36. Swift GRB 251201B: Global MASTER-Net observations report
  37. GRB 251201B: Swift detection of a burst with an optical counterpart
  38. GRB 251201B: Fermi GBM Final Real-time Localization
  39. EP251130a: Optical detections with Kinder observations
  40. SVOM GRB251201.19: Global MASTER-Net observations report
  41. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  42. EP251130A: Optical observation from 1.3m DFOT
  43. Fermi GRB 251130B: Global MASTER-Net observations report
  44. IceCube Alert 251130.75: Global MASTER-Net observations report
  45. EP251130a: Swift-XRT counterpart detection
  46. GRB 251130B: Fermi GBM Final Localization Correction
  47. EP251130a: Global MASTER-Net observations report
  48. GRB 251130B: Fermi GBM Final Real-time Localization
  49. EP251130a: COLIBRÍ optical counterpart candidate
  50. GRB 251130A: Fermi GBM Final Real-time Localization
  51. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  52. GRB 251128A: AstroSat CZTI detection
  53. SVOM GRB 251129A : MASTER optical counterpart detection
  54. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  55. Swift trigger 1418333 is not an astrophysical source
  56. GRB 251129A / EP251129a: SVOM/VT optical fading
  57. EP251129a: Global MASTER-Net observations report
  58. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  59. GRB 251128A: Fermi GBM Observation
  60. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  61. GRB 251129A: SVOM detection of a burst
  62. SVOM GRB251129A: Global MASTER-Net observations report
  63. GRB 251129A: SVOM detection of a burst
  64. GRB 251126A: Swift-BAT refined analysis
  65. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  66. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  67. Fermi GRB 251128A: Global MASTER-Net observations report
  68. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  69. GRB 251126A NUTTelA-TAO Early Measurements
  70. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  71. GRB251126A: MAO/AZT-22 optical observations
  72. GRB 251128A: Fermi GBM Final Real-time Localization
  73. GRB251126A: Continued optical observation from 1.3m DFOT
  74. GRB 251126A: Swift/UVOT Detection
  75. GRB 251126A: Mondy and SAO RAS optical observations
  76. GRB 251126A: Swift-XRT refined Analysis
  77. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  78. GRB 251126A: NOT optical observations
  79. GRB 251126A: 1.3m DFOT optical afterglow detection
  80. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  81. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  82. Fermi GRB 251127A: Global MASTER-Net observations report
  83. GRB 251127A: Fermi GBM Final Real-time Localization
  84. GRB 251126A: Asiago i-band detection
  85. GRB 251126A: Nanshan/HMT optical afterglow detection
  86. Swift GRB 251126A: Global MASTER-Net observations report
  87. GRB 251121A: Fermi GBM Observation
  88. GRB 251126A: GIT discovery of the likely optical afterglow
  89. GRB 251126A: Swift detection of a burst
  90. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  91. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  92. EP251124b: NOT r- and z-band optical upper limits
  93. Fermi GRB 251125B: Global MASTER-Net observations report
  94. GRB 251125B: Fermi GBM Final Real-time Localization
  95. EP251124b: Global MASTER-Net observations report
  96. EP251124a: Xinglong GWAC-F60A optical observation
  97. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  98. Fermi GRB 251125A: Global MASTER-Net observations report
  99. GRB 251125A: Fermi GBM Final Real-time Localization
  100. EP251124a: NOT r- and z-band optical upper limits

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