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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"

32509 results found.

  1. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  2. GRB 251205A: COLIBRÍ optical observations
  3. GRB 251205A: GOTO optical afterglow detection
  4. GRB 251205A: NOT optical observations
  5. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  6. Swift GRB 251205A : MASTER OT detection with host galaxy
  7. GRB 251203A: Insight-HXMT/HE detection
  8. GRB 251203C: SVOM/ECLAIRs refined analysis
  9. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  10. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. GRB 251202A: SVOM/GRM observation
  12. GRB 251203A: GECAM-B observation of a burst
  13. GRB 251203A: SVOM/GRM observation
  14. GRB 251201B: SALT spectroscopic redshift z = 1.599
  15. GRB 251203C: J-band observations with WINTER
  16. GRB 251129B: Glowbug gamma-ray detection of a short burst
  17. GRB 251203A: AstroSat CZTI detection
  18. EP251130a: JinShan near-infrared observations
  19. GRB 251203C: LCO optical afterglow confirmation
  20. GRB 251203C: SVOM/VT optical counterpart
  21. GRB 251203C: EP-FXT follow-up observation
  22. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  23. GRB 251203B: Swift-XRT observations
  24. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  25. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  26. GRB 251203C: LCO optical upper limits
  27. GRB 251203B: LCO optical upper limits
  28. GRB 251203B: SVOM/VT optical observation
  29. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  30. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  31. GRB 251201B: Insight-HXMT/HE detection
  32. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  33. EP251130a: MAO/AZT-22 optical observations
  34. EP251202a / GRB251202A: AstroSat CZTI detection
  35. GRB 251202A / EP251202a: SVOM/VT optical observation
  36. GRB 251201B: Fermi GBM Observation
  37. EP251202a/GRB 251202A: KAIT optical observations
  38. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  39. Fermi GRB 251202B: Global MASTER-Net observations report
  40. IPN triangulation of GRB 251129B (short/hard)
  41. GRB251129A/EP251129a: Swift UVOT detection
  42. GRB 251202A: Fermi GBM Observation
  43. GRB 251202A: Swift/UVOT Detection
  44. GRB 251201B: Kilonova-Catcher optical afterglow detection
  45. GRB 251201B: Swift/UVOT Detection
  46. GRB 251130B: Glowbug gamma-ray detection
  47. GRB 251201B: GECAM-B observation of a long burst
  48. EP251130a: continued NOT optical observations indicate steep fading phase
  49. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  50. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  51. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  52. GRB 251202A: GOTO optical afterglow detection
  53. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  54. GRB 251201A: GECAM-B observation of a burst
  55. GRB 251126A: SAO RAS optical marginal detection
  56. GRB 251202A: Swift-XRT afterglow detection
  57. EP251129a/GRB 251129A: NOWT Detection
  58. GRB 251126A: SVOM/VT optical observation
  59. EP251130a: SVOM/VT optical observation
  60. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  61. Fermi GRB 251202A: Global MASTER-Net observations report
  62. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  63. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 251201A: SVOM/GRM observation of a burst
  65. GRB 251201B: SVOM/VT optical fading
  66. Swift GRB 251201B : MASTER optical counterpart detection
  67. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  68. Swift GRB 251201B: Global MASTER-Net observations report
  69. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  70. GRB 251130B: AstroSat CZTI detection
  71. EP251130a: Mondy optical observations
  72. EP251130a: Optical detections with Kinder observations
  73. EP251130a: SAO RAS optical observations
  74. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  75. EP251130a: KAIT optical observations
  76. EP251130A: Optical observation from 1.3m DFOT
  77. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  78. EP251130a: JinShan optical observations
  79. Fermi GRB 251130B: Global MASTER-Net observations report
  80. GRB 251127A: SVOM/GRM observation
  81. EP251130a: Swift-XRT counterpart detection
  82. EP251130a: Global MASTER-Net observations report
  83. EP251130a: COLIBRÍ optical counterpart candidate
  84. EP251129a/GRB 251129A: EP-FXT follow-up observations
  85. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  86. GRB 251128A: AstroSat CZTI detection
  87. GRB 251129A / EP251129a: SAO RAS optical observations
  88. GRB 251126A: SAO RAS optical observations
  89. GRB 251128A: GECAM-B detection
  90. GRB 251128A: SVOM/GRM observation of a long burst
  91. GRB 251128A: Insight-HXMT/HE detection
  92. SVOM GRB 251129A : MASTER optical counterpart detection
  93. GRB 251129A: Swift-XRT afterglow detection
  94. GRB 251129A: Swift ToO observations
  95. GRB 251129A / EP251129a: SVOM/VT optical fading
  96. EP251129a: Global MASTER-Net observations report
  97. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  98. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  99. GRB 251129A: Correction to the position of the optical counterpar
  100. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data

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