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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"

28234 results found.

  1. IPN triangulation of GRB 251129B (short/hard)
  2. GRB251129A/EP251129a: Swift UVOT detection
  3. GRB 251202A: Fermi GBM Observation
  4. GRB 251202A: Swift/UVOT Detection
  5. GRB 251201B: Kilonova-Catcher optical afterglow detection
  6. GRB 251201B: Swift/UVOT Detection
  7. GRB 251130B: Glowbug gamma-ray detection
  8. EP251130a: continued NOT optical observations indicate steep fading phase
  9. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  10. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  11. GRB 251126A: SAO RAS optical marginal detection
  12. GRB 251202A: Swift-XRT afterglow detection
  13. EP251129a/GRB 251129A: NOWT Detection
  14. GRB 251126A: SVOM/VT optical observation
  15. EP251130a: SVOM/VT optical observation
  16. Fermi GRB 251202A: Global MASTER-Net observations report
  17. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  18. GRB 251201B: Swift-XRT refined Analysis
  19. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 251201A: SVOM/GRM observation of a burst
  21. GRB 251201B: SVOM/VT optical fading
  22. Swift GRB 251201B : MASTER optical counterpart detection
  23. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  24. Swift GRB 251201B: Global MASTER-Net observations report
  25. GRB 251201B: Enhanced Swift-XRT position
  26. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  27. GRB 251201B: Swift detection of a burst with an optical counterpart
  28. GRB 251201B: Fermi GBM Final Real-time Localization
  29. EP251130a: Mondy optical observations
  30. EP251130a: Optical detections with Kinder observations
  31. SVOM GRB251201.19: Global MASTER-Net observations report
  32. EP251130a: SAO RAS optical observations
  33. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  34. EP251130A: Optical observation from 1.3m DFOT
  35. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  36. EP251130a: JinShan optical observations
  37. GRB 251201A: MAXI/GSC detection
  38. Fermi GRB 251130B: Global MASTER-Net observations report
  39. GRB 251127A: SVOM/GRM observation
  40. IceCube Alert 251130.75: Global MASTER-Net observations report
  41. EP251130a: Swift-XRT counterpart detection
  42. EP251130a: Global MASTER-Net observations report
  43. EP251130a: COLIBRÍ optical counterpart candidate
  44. EP251130a: Einstein Probe detection of an X-ray transient
  45. GRB 251129A / EP251129a: SAO RAS optical observations
  46. GRB 251126A: SAO RAS optical observations
  47. GRB 251128A: SVOM/GRM observation of a long burst
  48. SVOM GRB 251129A : MASTER optical counterpart detection
  49. GRB 251129A: Swift-XRT afterglow detection
  50. EP251129a: Global MASTER-Net observations report
  51. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  52. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  53. GRB 251128A: Fermi GBM Observation
  54. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  55. GRB 251129A: SVOM detection of a burst
  56. SVOM GRB251129A: Global MASTER-Net observations report
  57. GRB 251129A: SVOM detection of a burst
  58. GRB 251126A: Swift-BAT refined analysis
  59. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  60. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  61. Fermi GRB 251128A: Global MASTER-Net observations report
  62. GRB 251127A: Glowbug gamma-ray detection
  63. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  64. GRB 251126A: further SAO RAS optical observations
  65. GRB 251126A NUTTelA-TAO Early Measurements
  66. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  67. GRB251126A: MAO/AZT-22 optical observations
  68. GRB251126A: Continued optical observation from 1.3m DFOT
  69. GRB 251126A: Swift/UVOT Detection
  70. GRB 251126A: Mondy and SAO RAS optical observations
  71. GRB 251126A: Swift-XRT refined Analysis
  72. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  73. GRB 251126A: NOT optical observations
  74. GRB 251126A: 1.3m DFOT optical afterglow detection
  75. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  76. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  77. Fermi GRB 251127A: Global MASTER-Net observations report
  78. GRB 251126A: Enhanced Swift-XRT position
  79. GRB 251126A: Kilonova-Catcher optical afterglow detection
  80. GRB 251126A: Nanshan/HMT optical afterglow detection
  81. Swift GRB 251126A: Global MASTER-Net observations report
  82. GRB 251121A: Fermi GBM Observation
  83. GRB 251126A: GIT discovery of the likely optical afterglow
  84. GRB 251126A: Swift detection of a burst
  85. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  86. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  87. EP251124b: NOT r- and z-band optical upper limits
  88. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  89. Fermi GRB 251125B: Global MASTER-Net observations report
  90. EP251124b: Global MASTER-Net observations report
  91. EP251124b: EP-WXT detection of a fast X-ray transient
  92. EP251124a: Xinglong GWAC-F60A optical observation
  93. Fermi GRB 251125A: Global MASTER-Net observations report
  94. EP251124a: NOT r- and z-band optical upper limits
  95. EP251124a: Global MASTER-Net observations report
  96. EP251124a: Swift-XRT observations
  97. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  98. EP251124a: Optical upper limit with Kinder observations
  99. Fermi GRB 251124a: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901

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