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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"

28052 results found.

  1. GRB 251203A: SVOM/GRM observation
  2. GRB 251203C: J-band observations with WINTER
  3. GRB 251129B: Glowbug gamma-ray detection of a short burst
  4. GRB 251203A: AstroSat CZTI detection
  5. GRB 251203C: SVOM/VT optical counterpart
  6. GRB 251203C: EP-FXT follow-up observation
  7. GRB 251203B: Swift-XRT observations
  8. GRB 251203C: LCO optical upper limits
  9. GRB 251203B: LCO optical upper limits
  10. GRB 251203B: SVOM/VT optical observation
  11. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  12. SVOM GRB251203.77: Global MASTER-Net observations report
  13. SVOM GRB251203B: Global MASTER-Net observations report
  14. GRB 251203B: SVOM detection of a burst
  15. EP251130a: MAO/AZT-22 optical observations
  16. GRB 251201B: Fermi GBM Observation
  17. EP251202a/GRB 251202A: KAIT optical observations
  18. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  19. Fermi GRB 251202B: Global MASTER-Net observations report
  20. IPN triangulation of GRB 251129B (short/hard)
  21. GRB251129A/EP251129a: Swift UVOT detection
  22. GRB 251202A: Fermi GBM Observation
  23. GRB 251202A: Swift/UVOT Detection
  24. GRB 251201B: Kilonova-Catcher optical afterglow detection
  25. GRB 251201B: Swift/UVOT Detection
  26. GRB 251130B: Glowbug gamma-ray detection
  27. EP251130a: continued NOT optical observations indicate steep fading phase
  28. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  29. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  30. GRB 251126A: SAO RAS optical marginal detection
  31. GRB 251202A: Swift-XRT afterglow detection
  32. EP251129a/GRB 251129A: NOWT Detection
  33. GRB 251126A: SVOM/VT optical observation
  34. EP251130a: SVOM/VT optical observation
  35. Fermi GRB 251202A: Global MASTER-Net observations report
  36. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  37. GRB 251201B: Swift-XRT refined Analysis
  38. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 251201A: SVOM/GRM observation of a burst
  40. GRB 251201B: SVOM/VT optical fading
  41. Swift GRB 251201B : MASTER optical counterpart detection
  42. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  43. Swift GRB 251201B: Global MASTER-Net observations report
  44. GRB 251201B: Enhanced Swift-XRT position
  45. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  46. GRB 251201B: Swift detection of a burst with an optical counterpart
  47. GRB 251201B: Fermi GBM Final Real-time Localization
  48. EP251130a: Mondy optical observations
  49. EP251130a: Optical detections with Kinder observations
  50. SVOM GRB251201.19: Global MASTER-Net observations report
  51. EP251130a: SAO RAS optical observations
  52. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  53. EP251130A: Optical observation from 1.3m DFOT
  54. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP251130a: JinShan optical observations
  56. GRB 251201A: MAXI/GSC detection
  57. Fermi GRB 251130B: Global MASTER-Net observations report
  58. GRB 251127A: SVOM/GRM observation
  59. IceCube Alert 251130.75: Global MASTER-Net observations report
  60. EP251130a: Swift-XRT counterpart detection
  61. EP251130a: Global MASTER-Net observations report
  62. EP251130a: COLIBRÍ optical counterpart candidate
  63. EP251130a: Einstein Probe detection of an X-ray transient
  64. GRB 251129A / EP251129a: SAO RAS optical observations
  65. GRB 251126A: SAO RAS optical observations
  66. GRB 251128A: SVOM/GRM observation of a long burst
  67. SVOM GRB 251129A : MASTER optical counterpart detection
  68. GRB 251129A: Swift-XRT afterglow detection
  69. EP251129a: Global MASTER-Net observations report
  70. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  71. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  72. GRB 251128A: Fermi GBM Observation
  73. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  74. GRB 251129A: SVOM detection of a burst
  75. SVOM GRB251129A: Global MASTER-Net observations report
  76. GRB 251129A: SVOM detection of a burst
  77. GRB 251126A: Swift-BAT refined analysis
  78. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  79. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  80. Fermi GRB 251128A: Global MASTER-Net observations report
  81. GRB 251127A: Glowbug gamma-ray detection
  82. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  83. GRB 251126A: further SAO RAS optical observations
  84. GRB 251126A NUTTelA-TAO Early Measurements
  85. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  86. GRB251126A: MAO/AZT-22 optical observations
  87. GRB251126A: Continued optical observation from 1.3m DFOT
  88. GRB 251126A: Swift/UVOT Detection
  89. GRB 251126A: Mondy and SAO RAS optical observations
  90. GRB 251126A: Swift-XRT refined Analysis
  91. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  92. GRB 251126A: NOT optical observations
  93. GRB 251126A: 1.3m DFOT optical afterglow detection
  94. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  95. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  96. Fermi GRB 251127A: Global MASTER-Net observations report
  97. GRB 251126A: Enhanced Swift-XRT position
  98. GRB 251126A: Kilonova-Catcher optical afterglow detection
  99. GRB 251126A: Nanshan/HMT optical afterglow detection
  100. Swift GRB 251126A: Global MASTER-Net observations report

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