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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"

14827 results found.

  1. GRB 250404A / EP250404a: GRBAlpha detection
  2. GRB 250330B: GRBAlpha detection
  3. GRB 250424A: AstroSat CZTI detection of a bright long burst
  4. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  5. GRB 250424A: BlackGEM optical afterglow detection
  6. GRB 250424A: DDOTI Afterglow Detection
  7. GRB 250424A: REM optical/NIR afterglow detection
  8. GRB 250424A: Swift detection of a burst with an optical counterpart
  9. Swift GRB 250424A: Global MASTER-Net OT detection
  10. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  11. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  12. SVOM/sb25042207: BOOTES-2 early optical upper limit
  13. GRB 250421A: AstroSat CZTI detection
  14. SVOM/sb25042207: SVOM detection of an X-ray transient
  15. GRB250419A: VLA radio detection
  16. IceCube-250421A: DDOTI Detection of the LAST Candidate
  17. GRB 250419A: Mephisto Multi-band Optical Detection
  18. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  19. GRB 250419A: Optical Observations via Virtual Telescope Project
  20. EP250421a: Swift/XRT counterpart detection
  21. GRB 250421B: AstroSat CZTI detection of a bright long burst
  22. EP250421a: Einstein Probe detection of an X-ray transient
  23. EP250421a: Mephisto optical counterpart confirmation
  24. IceCube-250421A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 250421A: Fermi GBM Final Real-time Localization
  26. GRB 250419A: Liverpool Telescope observations
  27. GRB 250419A: LCO optical afterglow multi-band observations
  28. GRB 250419A: AKO Optical Afterglow Detection
  29. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  30. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  31. GRB 250419A: GOTO optical counterpart detection
  32. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  33. GRB 250419A: SVOM detection of a soft burst
  34. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  35. Konus-Wind detection of GRB 250403A
  36. EP20250416a: Swift/XRT counterpart detection
  37. EP250416a: Gemini South-GMOS optical counterpart
  38. EP250416a: GSP optical upper limit
  39. EP250416a: Einstein Probe detection of an X-ray transient
  40. IceCube-250416A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 250416B: Fermi GBM Final Real-time Localization
  42. GRB 250416A: Fermi GBM Final Real-time Localization
  43. SVOM/sb25041603: SVOM detection of an X-ray transient
  44. GRB 250413A: AstroSat CZTI detection
  45. GRB 250412A: AstroSat CZTI detection
  46. EP250404a: Nanshan 0.43m Telescope optical observatios
  47. GRB 250411A: Fermi GBM Final Real-time Localization
  48. GRB 250320B: cubesat Avion detection
  49. IceCube-250406A: Swift-XRT observations
  50. IPN triangulation of GRB 250407A
  51. GRB 250407A: LCO detection of a fading optical counterpart
  52. EP250407a: Swift-XRT observations
  53. Konus-Wind detection of GRB 250407A
  54. GRB 250407A: EP-WXT afterglow detection
  55. EP250407a: EP-WXT detection of a fast X-ray transient
  56. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  57. GRB 250407A: Fermi GBM Detection
  58. GRB 250407A: Swift-XRT afterglow detection
  59. GRB 250407A: SRG/ART-XC afterglow detection
  60. Konus-Wind detection of GRB 250406B (short/hard)
  61. GRB 250407A: Fermi GBM Final Real-time Localization
  62. IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
  63. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  64. GRB 250406A: AstroSat CZTI detection
  65. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  66. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  67. GRB 250406A: Fermi GBM Final Real-time Localization
  68. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  69. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  70. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  71. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  72. Konus-Wind detection of GRB 250404A / EP250404a
  73. GRB 250404A / EP250404a: Mondy optical observations
  74. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  75. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  76. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  77. GRB 250404A / EP250404a: NOT optical observations
  78. GRB 250331D: Swift-XRT afterglow detection
  79. GRB 250404B: AstroSat CZTI detection of a short burst
  80. GRB 250403A: AstroSat CZTI detection
  81. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  82. EP250404a: REM optical/NIR observations
  83. EP250404a: Seimei/TriCCS optical counterpart detection
  84. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  85. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  86. EP250404a: LCO optical counterpart detection
  87. EP250404a: Xinglong decaying optical counterpart
  88. GRB 250403A: Montarrenti Observatory optical detection
  89. GRB 250404A: Fermi GBM Detection
  90. EP250404a: AKO Optical Afterglow Detection
  91. EP250404a: LAST detection of optical counterpart
  92. EP250404a: Xinglong-2.16m spectroscopic redshift
  93. GRB 250327B: VIRT Optical Upper Limit
  94. EP250404a: Mephisto multi-band optical detection
  95. EP250404a: BOOTES-4/JGT optical afterglow detection
  96. EP250404a: Nanshan/HMT optical counterpart detection
  97. EP250404a: Einstein Probe detection of an X-ray transient
  98. GRB 250404A: Fermi GBM Final Real-time Localization
  99. GRB 250403A: Swift/UVOT Detection
  100. GRB 250402A: Swift/UVOT Upper Limits

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