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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"

42981 results found.

  1. GRB 251208A: Fermi GBM Final Real-time Localization
  2. GRB 251205A: FTW optical and NIR observations
  3. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  4. GRB 251205A: Liverpool Telescope further optical follow-up observations
  5. SVOM GRB251206.86: Global MASTER-Net observations report
  6. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  7. The EP-WXT trigger 01709249380 is likely a flaring star
  8. GRB 251205A: ZTF and ATLAS optical afterglow detections
  9. GRB 251205A: GROWTH-India Telescope optical observations
  10. GRB 251205A: Swift-BAT refined analysis
  11. GRB 251205A: Swift-XRT 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. GRB 251205A: Enhanced Swift-XRT position
  22. Swift GRB 251205A : MASTER OT detection with host galaxy
  23. GRB 251205A: Swift detection of a burst with an optical afterglow
  24. Swift GRB251205A: Global MASTER-Net observations report
  25. GRB 251126B: Fermi GBM Final Localization
  26. GRB 251203A: Insight-HXMT/HE detection
  27. GRB 251203C: SVOM/ECLAIRs refined analysis
  28. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  29. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  30. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 251202A: SVOM/GRM observation
  32. GRB 251203A: GECAM-B observation of a burst
  33. GRB 251203A: SVOM/GRM observation
  34. GRB 251201B: SALT spectroscopic redshift z = 1.599
  35. GRB 251203C: J-band observations with WINTER
  36. GRB 251129B: Glowbug gamma-ray detection of a short burst
  37. GRB 251203A: AstroSat CZTI detection
  38. EP251130a: JinShan near-infrared observations
  39. GRB 251203C: LCO optical afterglow confirmation
  40. GRB 251203C: SVOM/VT optical counterpart
  41. GRB 251203C: EP-FXT follow-up observation
  42. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  43. GRB 251129B: GECAM-B observation of a burst
  44. GRB 251203B: Swift-XRT observations
  45. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  46. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  47. GRB 251203C: LCO optical upper limits
  48. GRB 251203B: LCO optical upper limits
  49. GRB 251203B: SVOM/VT optical observation
  50. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  51. GRB 251203C: SVOM detection of a burst
  52. SVOM GRB251203.77: Global MASTER-Net observations report
  53. SVOM GRB251203B: Global MASTER-Net observations report
  54. GRB 251203B: SVOM detection of a burst
  55. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  56. GRB 251201B: Insight-HXMT/HE detection
  57. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  58. EP251130a: MAO/AZT-22 optical observations
  59. GRB 251203A: Fermi GBM Final Real-time Localization
  60. EP251202a / GRB251202A: AstroSat CZTI detection
  61. GRB 251202A / EP251202a: SVOM/VT optical observation
  62. GRB 251201B: Fermi GBM Observation
  63. EP251202a/GRB 251202A: KAIT optical observations
  64. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  65. Fermi GRB 251202B: Global MASTER-Net observations report
  66. GRB 251202B: Fermi GBM Final Real-time Localization
  67. IPN triangulation of GRB 251129B (short/hard)
  68. GRB251129A/EP251129a: Swift UVOT detection
  69. GRB 251129B: AstroSat CZTI detection
  70. GRB 251202A: Fermi GBM Observation
  71. GRB 251202A: Swift/UVOT Detection
  72. GRB 251201B: Kilonova-Catcher optical afterglow detection
  73. GRB 251201B: Swift/UVOT Detection
  74. GRB 251130B: Glowbug gamma-ray detection
  75. GRB 251201B: GECAM-B observation of a long burst
  76. EP251130a: continued NOT optical observations indicate steep fading phase
  77. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  78. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  79. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  80. GRB 251202A: GOTO optical afterglow detection
  81. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  82. GRB 251201A: GECAM-B observation of a burst
  83. GRB 251126A: SAO RAS optical marginal detection
  84. GRB 251202A: Swift-XRT afterglow detection
  85. EP251129a/GRB 251129A: NOWT Detection
  86. GRB 251126A: SVOM/VT optical observation
  87. EP251130a: SVOM/VT optical observation
  88. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  89. Fermi GRB 251202A: Global MASTER-Net observations report
  90. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  91. GRB 251201B: Swift-XRT refined Analysis
  92. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  93. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  94. GRB 251202A: Fermi GBM Final Real-time Localization
  95. GRB 251201A: SVOM/GRM observation of a burst
  96. GRB 251201B: SVOM/VT optical fading
  97. Swift GRB 251201B : MASTER optical counterpart detection
  98. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  99. Swift GRB 251201B: Global MASTER-Net observations report
  100. GRB 251201B: Enhanced Swift-XRT position

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