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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"

28095 results found.

  1. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  2. Konus-Wind detection of GRB 250207A
  3. Konus-Wind detection of GRB 250206A
  4. EP250207b: Liverpool Telescope possible optical counterpart
  5. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  6. GRB 250207A: Skynet optical afterglow observations
  7. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  8. GRB 241128A: VIRT Optical Upper Limit
  9. GRB 250210A: INTEGRAL SPI-ACS detection
  10. GRB 250210A: AstroSat CZTI detection
  11. EP250207b: a new X-ray transient detected by Einstein Probe
  12. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  13. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  14. GRB 250210A: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  16. GRB 250204B: GRBAlpha detection
  17. GRB 250204A: GRBAlpha detection
  18. GRB 250207A: 1.3m DFOT Optical observations
  19. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  20. GRB 250206A: Swift-XRT observations
  21. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  22. GRB 250129A: GRANDMA Continued Afterglow Detection
  23. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  24. GRB 250205A: 1.3m DFOT optical upper limit
  25. GRB 250206A: Tiled Swift observations
  26. GRB 250206A: EIRSAT-1 GMOD Detection
  27. GRB 250206A: Fermi-LAT detection
  28. GRB 250207B: Swift-XRT observations
  29. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  30. GRB 250208A: Fermi GBM Final Real-time Localization
  31. EP250207a: EP-WXT detection and XRT follow-up observation
  32. GRB 250207A: Swift-XRT refined Analysis
  33. GRB 250207A: Enhanced Swift-XRT position
  34. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  35. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  36. GRB 250207A: REM IR afterglow detection
  37. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  38. GRB 250207A: FRAM-Auger optical detection
  39. GRB 250207B: Tiled Swift observations
  40. Konus-Wind detection of GRB 250204B
  41. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 250207A: REM optical afterglow detection
  43. GRB 250207A: Swift/UVOT Detection
  44. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  45. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  46. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  47. GRB 250207B: MAXI/GSC detection
  48. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  49. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  50. GRB 250207A: Swift detection of a burst with optical counterpart
  51. GRB 250207A: Fermi GBM Final Real-time Localization
  52. GRB 250206A: Fermi GBM Final Real-time Localization
  53. GRB 250205A: Fermi GBM Observation
  54. GRB 250205A: REM NIR upper limit
  55. GRB 250205A: Swift/UVOT Upper Limits
  56. EP250205a/GRB 250205A: Einstein Probe observation
  57. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  58. GRB 250205A: Swift/XRT detection
  59. GRB250205A: SVOM/VT optical afterglow detection
  60. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  61. GRB 250205A: SVOM detection of a burst
  62. Konus-Wind detection of GRB 250201A
  63. IPN triangulation of GRB 250201A
  64. Konus-Wind detection of GRB 250202B
  65. IPN triangulation of GRB 250204B (short/hard)
  66. IPN triangulation of GRB 250202B
  67. GRB 250204B: AstroSat CZTI detection of a short burst
  68. GRB 250204B: Fermi GBM Final Localization
  69. GRB 250129A: LCO late afterglow detection
  70. GRB 250204A: Fermi GBM Final Real-time Localization
  71. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  72. GRB 250202B: NuSTAR detection of the prompt emission
  73. GRB 250202C: GRBAlpha detection
  74. GRB 250202B: Fermi GBM Detection
  75. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 250129a: Liverpool Telescope optical follow-up
  77. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  78. GRB 250202C: Fermi GBM Final Real-time Localization
  79. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  80. LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate
  81. GRB 250202B: Fermi GBM Final Real-time Localization
  82. GRB 250202A: Fermi GBM Final Real-time Localization
  83. GRB 250201A: INTEGRAL SPI/ACS detection
  84. Konus-Wind detection of GRB 250129A
  85. GRB 250129A: 1.3m DFOT Optical observations
  86. GRB 250201A: Fermi GBM Final Real-time Localization
  87. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  88. GRB 250129A: optical photometry from Konkoly
  89. GRB 250129A: COLIBRÍ Optical Observations
  90. GRB 250128B: VLA possible radio detection
  91. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  92. GRB 250129A: iTelescope optical observation
  93. GRB 250129A: NOT optical observations of continuining activity
  94. GRB 250129a: Liverpool Telescope optical follow-up
  95. GRB 250129A: TNG NIR afterglow detection
  96. GRB 250129A: AKO Optical Afterglow Detection
  97. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  98. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  99. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  100. GRB 250128B: VLA radio upper limit

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