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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28247 results found.

  1. GRB 251203C: EP-FXT follow-up observation
  2. GRB 251203B: Swift-XRT observations
  3. GRB 251203C: LCO optical upper limits
  4. GRB 251203B: LCO optical upper limits
  5. GRB 251203B: SVOM/VT optical observation
  6. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  7. SVOM GRB251203.77: Global MASTER-Net observations report
  8. SVOM GRB251203B: Global MASTER-Net observations report
  9. GRB 251203B: SVOM detection of a burst
  10. EP251130a: MAO/AZT-22 optical observations
  11. GRB 251201B: Fermi GBM Observation
  12. EP251202a/GRB 251202A: KAIT optical observations
  13. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  14. Fermi GRB 251202B: Global MASTER-Net observations report
  15. IPN triangulation of GRB 251129B (short/hard)
  16. GRB251129A/EP251129a: Swift UVOT detection
  17. GRB 251202A: Fermi GBM Observation
  18. GRB 251202A: Swift/UVOT Detection
  19. GRB 251201B: Kilonova-Catcher optical afterglow detection
  20. GRB 251201B: Swift/UVOT Detection
  21. GRB 251130B: Glowbug gamma-ray detection
  22. EP251130a: continued NOT optical observations indicate steep fading phase
  23. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  24. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  25. GRB 251126A: SAO RAS optical marginal detection
  26. GRB 251202A: Swift-XRT afterglow detection
  27. EP251129a/GRB 251129A: NOWT Detection
  28. GRB 251126A: SVOM/VT optical observation
  29. EP251130a: SVOM/VT optical observation
  30. Fermi GRB 251202A: Global MASTER-Net observations report
  31. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  32. GRB 251201B: Swift-XRT refined Analysis
  33. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 251201A: SVOM/GRM observation of a burst
  35. GRB 251201B: SVOM/VT optical fading
  36. Swift GRB 251201B : MASTER optical counterpart detection
  37. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  38. Swift GRB 251201B: Global MASTER-Net observations report
  39. GRB 251201B: Enhanced Swift-XRT position
  40. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  41. GRB 251201B: Swift detection of a burst with an optical counterpart
  42. GRB 251201B: Fermi GBM Final Real-time Localization
  43. EP251130a: Mondy optical observations
  44. EP251130a: Optical detections with Kinder observations
  45. SVOM GRB251201.19: Global MASTER-Net observations report
  46. EP251130a: SAO RAS optical observations
  47. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  48. EP251130A: Optical observation from 1.3m DFOT
  49. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  50. EP251130a: JinShan optical observations
  51. GRB 251201A: MAXI/GSC detection
  52. Fermi GRB 251130B: Global MASTER-Net observations report
  53. GRB 251127A: SVOM/GRM observation
  54. IceCube Alert 251130.75: Global MASTER-Net observations report
  55. EP251130a: Swift-XRT counterpart detection
  56. EP251130a: Global MASTER-Net observations report
  57. EP251130a: COLIBRÍ optical counterpart candidate
  58. EP251130a: Einstein Probe detection of an X-ray transient
  59. GRB 251129A / EP251129a: SAO RAS optical observations
  60. GRB 251126A: SAO RAS optical observations
  61. GRB 251128A: SVOM/GRM observation of a long burst
  62. SVOM GRB 251129A : MASTER optical counterpart detection
  63. GRB 251129A: Swift-XRT afterglow detection
  64. EP251129a: Global MASTER-Net observations report
  65. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  66. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  67. GRB 251128A: Fermi GBM Observation
  68. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  69. GRB 251129A: SVOM detection of a burst
  70. SVOM GRB251129A: Global MASTER-Net observations report
  71. GRB 251129A: SVOM detection of a burst
  72. GRB 251126A: Swift-BAT refined analysis
  73. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  74. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  75. Fermi GRB 251128A: Global MASTER-Net observations report
  76. GRB 251127A: Glowbug gamma-ray detection
  77. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  78. GRB 251126A: further SAO RAS optical observations
  79. GRB 251126A NUTTelA-TAO Early Measurements
  80. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  81. GRB251126A: MAO/AZT-22 optical observations
  82. GRB251126A: Continued optical observation from 1.3m DFOT
  83. GRB 251126A: Swift/UVOT Detection
  84. GRB 251126A: Mondy and SAO RAS optical observations
  85. GRB 251126A: Swift-XRT refined Analysis
  86. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  87. GRB 251126A: NOT optical observations
  88. GRB 251126A: 1.3m DFOT optical afterglow detection
  89. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  90. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  91. Fermi GRB 251127A: Global MASTER-Net observations report
  92. GRB 251126A: Enhanced Swift-XRT position
  93. GRB 251126A: Kilonova-Catcher optical afterglow detection
  94. GRB 251126A: Nanshan/HMT optical afterglow detection
  95. Swift GRB 251126A: Global MASTER-Net observations report
  96. GRB 251121A: Fermi GBM Observation
  97. GRB 251126A: GIT discovery of the likely optical afterglow
  98. GRB 251126A: Swift detection of a burst
  99. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  100. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate

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