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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"

26339 results found.

  1. GRB 251203B: SVOM detection of a burst
  2. EP251130a: MAO/AZT-22 optical observations
  3. GRB 251201B: Fermi GBM Observation
  4. EP251202a/GRB 251202A: KAIT optical observations
  5. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  6. Fermi GRB 251202B: Global MASTER-Net observations report
  7. IPN triangulation of GRB 251129B (short/hard)
  8. GRB251129A/EP251129a: Swift UVOT detection
  9. GRB 251202A: Fermi GBM Observation
  10. GRB 251202A: Swift/UVOT Detection
  11. GRB 251201B: Kilonova-Catcher optical afterglow detection
  12. GRB 251201B: Swift/UVOT Detection
  13. GRB 251130B: Glowbug gamma-ray detection
  14. EP251130a: continued NOT optical observations indicate steep fading phase
  15. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  16. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  17. GRB 251126A: SAO RAS optical marginal detection
  18. GRB 251202A: Swift-XRT afterglow detection
  19. EP251129a/GRB 251129A: NOWT Detection
  20. GRB 251126A: SVOM/VT optical observation
  21. EP251130a: SVOM/VT optical observation
  22. Fermi GRB 251202A: Global MASTER-Net observations report
  23. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  24. GRB 251201B: Swift-XRT refined Analysis
  25. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 251201A: SVOM/GRM observation of a burst
  27. GRB 251201B: SVOM/VT optical fading
  28. Swift GRB 251201B : MASTER optical counterpart detection
  29. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  30. Swift GRB 251201B: Global MASTER-Net observations report
  31. GRB 251201B: Enhanced Swift-XRT position
  32. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  33. GRB 251201B: Swift detection of a burst with an optical counterpart
  34. GRB 251201B: Fermi GBM Final Real-time Localization
  35. EP251130a: Mondy optical observations
  36. EP251130a: Optical detections with Kinder observations
  37. SVOM GRB251201.19: Global MASTER-Net observations report
  38. EP251130a: SAO RAS optical observations
  39. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  40. EP251130A: Optical observation from 1.3m DFOT
  41. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  42. EP251130a: JinShan optical observations
  43. GRB 251201A: MAXI/GSC detection
  44. Fermi GRB 251130B: Global MASTER-Net observations report
  45. GRB 251127A: SVOM/GRM observation
  46. IceCube Alert 251130.75: Global MASTER-Net observations report
  47. EP251130a: Swift-XRT counterpart detection
  48. EP251130a: Global MASTER-Net observations report
  49. EP251130a: COLIBRÍ optical counterpart candidate
  50. EP251130a: Einstein Probe detection of an X-ray transient
  51. GRB 251129A / EP251129a: SAO RAS optical observations
  52. GRB 251126A: SAO RAS optical observations
  53. GRB 251128A: SVOM/GRM observation of a long burst
  54. SVOM GRB 251129A : MASTER optical counterpart detection
  55. GRB 251129A: Swift-XRT afterglow detection
  56. EP251129a: Global MASTER-Net observations report
  57. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  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 251127A: Glowbug gamma-ray detection
  69. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  70. GRB 251126A: further SAO RAS optical observations
  71. GRB 251126A NUTTelA-TAO Early Measurements
  72. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  73. GRB251126A: MAO/AZT-22 optical observations
  74. GRB251126A: Continued optical observation from 1.3m DFOT
  75. GRB 251126A: Swift/UVOT Detection
  76. GRB 251126A: Mondy and SAO RAS optical observations
  77. GRB 251126A: Swift-XRT refined Analysis
  78. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  79. GRB 251126A: NOT optical observations
  80. GRB 251126A: 1.3m DFOT optical afterglow detection
  81. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  82. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  83. Fermi GRB 251127A: Global MASTER-Net observations report
  84. GRB 251126A: Enhanced Swift-XRT position
  85. GRB 251126A: Kilonova-Catcher optical afterglow detection
  86. GRB 251126A: Nanshan/HMT optical afterglow detection
  87. Swift GRB 251126A: Global MASTER-Net observations report
  88. GRB 251121A: Fermi GBM Observation
  89. GRB 251126A: GIT discovery of the likely optical afterglow
  90. GRB 251126A: Swift detection of a burst
  91. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  92. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  93. EP251124b: NOT r- and z-band optical upper limits
  94. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  95. Fermi GRB 251125B: Global MASTER-Net observations report
  96. EP251124b: Global MASTER-Net observations report
  97. EP251124b: EP-WXT detection of a fast X-ray transient
  98. EP251124a: Xinglong GWAC-F60A optical observation
  99. Fermi GRB 251125A: Global MASTER-Net observations report
  100. EP251124a: NOT r- and z-band optical upper limits

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