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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"

32725 results found.

  1. GRB 251208B: Fermi-LAT detection
  2. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  3. GRB 251208D: SVOM possible detection of a faint burst
  4. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  5. GRB 251205A: FTW optical and NIR observations
  6. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  7. GRB 251205A: Liverpool Telescope further optical follow-up observations
  8. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  9. GRB 251205A: ZTF and ATLAS optical afterglow detections
  10. GRB 251205A: GROWTH-India Telescope optical observations
  11. GRB 251205A: Swift-BAT refined analysis
  12. GRB 251205A: Swift/UVOT Detection
  13. GRB 251205A: Liverpool Telescope optical follow-up observations
  14. GRB 251203C: Swift/UVOT Upper Limit
  15. Konus-Wind detection of GRB 251118A
  16. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  17. GRB 251205A: COLIBRÍ optical observations
  18. GRB 251205A: GOTO optical afterglow detection
  19. GRB 251205A: NOT optical observations
  20. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  21. Swift GRB 251205A : MASTER OT detection with host galaxy
  22. GRB 251203A: Insight-HXMT/HE detection
  23. GRB 251203C: SVOM/ECLAIRs refined analysis
  24. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  25. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. GRB 251202A: SVOM/GRM observation
  27. GRB 251203A: GECAM-B observation of a burst
  28. GRB 251203A: SVOM/GRM observation
  29. GRB 251201B: SALT spectroscopic redshift z = 1.599
  30. GRB 251203C: J-band observations with WINTER
  31. GRB 251129B: Glowbug gamma-ray detection of a short burst
  32. GRB 251203A: AstroSat CZTI detection
  33. EP251130a: JinShan near-infrared observations
  34. GRB 251203C: LCO optical afterglow confirmation
  35. GRB 251203C: SVOM/VT optical counterpart
  36. GRB 251203C: EP-FXT follow-up observation
  37. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  38. GRB 251203B: Swift-XRT observations
  39. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  40. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  41. GRB 251203C: LCO optical upper limits
  42. GRB 251203B: LCO optical upper limits
  43. GRB 251203B: SVOM/VT optical observation
  44. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  45. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  46. GRB 251201B: Insight-HXMT/HE detection
  47. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  48. EP251130a: MAO/AZT-22 optical observations
  49. EP251202a / GRB251202A: AstroSat CZTI detection
  50. GRB 251202A / EP251202a: SVOM/VT optical observation
  51. GRB 251201B: Fermi GBM Observation
  52. EP251202a/GRB 251202A: KAIT optical observations
  53. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  54. Fermi GRB 251202B: Global MASTER-Net observations report
  55. IPN triangulation of GRB 251129B (short/hard)
  56. GRB251129A/EP251129a: Swift UVOT detection
  57. GRB 251202A: Fermi GBM Observation
  58. GRB 251202A: Swift/UVOT Detection
  59. GRB 251201B: Kilonova-Catcher optical afterglow detection
  60. GRB 251201B: Swift/UVOT Detection
  61. GRB 251130B: Glowbug gamma-ray detection
  62. GRB 251201B: GECAM-B observation of a long burst
  63. EP251130a: continued NOT optical observations indicate steep fading phase
  64. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  65. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  66. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  67. GRB 251202A: GOTO optical afterglow detection
  68. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  69. GRB 251201A: GECAM-B observation of a burst
  70. GRB 251126A: SAO RAS optical marginal detection
  71. GRB 251202A: Swift-XRT afterglow detection
  72. EP251129a/GRB 251129A: NOWT Detection
  73. GRB 251126A: SVOM/VT optical observation
  74. EP251130a: SVOM/VT optical observation
  75. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  76. Fermi GRB 251202A: Global MASTER-Net observations report
  77. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  78. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 251201A: SVOM/GRM observation of a burst
  80. GRB 251201B: SVOM/VT optical fading
  81. Swift GRB 251201B : MASTER optical counterpart detection
  82. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  83. Swift GRB 251201B: Global MASTER-Net observations report
  84. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  85. GRB 251130B: AstroSat CZTI detection
  86. EP251130a: Mondy optical observations
  87. EP251130a: Optical detections with Kinder observations
  88. EP251130a: SAO RAS optical observations
  89. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  90. EP251130a: KAIT optical observations
  91. EP251130A: Optical observation from 1.3m DFOT
  92. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  93. EP251130a: JinShan optical observations
  94. Fermi GRB 251130B: Global MASTER-Net observations report
  95. GRB 251127A: SVOM/GRM observation
  96. EP251130a: Swift-XRT counterpart detection
  97. EP251130a: Global MASTER-Net observations report
  98. EP251130a: COLIBRÍ optical counterpart candidate
  99. EP251129a/GRB 251129A: EP-FXT follow-up observations
  100. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460

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