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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"

14323 results found.

  1. GRB 250205A / EP250205A: radio detection with the VLA
  2. IceCube-250207A: One candidate from the Zwicky Transient Facility
  3. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  4. Konus-Wind detection of GRB 250207A
  5. Konus-Wind detection of GRB 250206A
  6. EP250207b: Liverpool Telescope possible optical counterpart
  7. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  8. GRB 250207A: Skynet optical afterglow observations
  9. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  10. GRB 241128A: VIRT Optical Upper Limit
  11. GRB 250210A: INTEGRAL SPI-ACS detection
  12. GRB 250210A: AstroSat CZTI detection
  13. EP250207b: a new X-ray transient detected by Einstein Probe
  14. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  15. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  16. GRB 250210A: Fermi GBM Final Real-time Localization
  17. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  18. GRB 250204B: GRBAlpha detection
  19. GRB 250204A: GRBAlpha detection
  20. GRB 250207A: 1.3m DFOT Optical observations
  21. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  22. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  23. GRB 250129A: GRANDMA Continued Afterglow Detection
  24. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  25. GRB 250205A: 1.3m DFOT optical upper limit
  26. GRB 250206A: EIRSAT-1 GMOD Detection
  27. GRB 250206A: Fermi-LAT detection
  28. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  29. GRB 250208A: Fermi GBM Final Real-time Localization
  30. EP250207a: EP-WXT detection and XRT follow-up observation
  31. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  32. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  33. GRB 250207A: REM IR afterglow detection
  34. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  35. GRB 250207A: FRAM-Auger optical detection
  36. Konus-Wind detection of GRB 250204B
  37. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 250207A: REM optical afterglow detection
  39. GRB 250207A: Swift/UVOT Detection
  40. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  41. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  42. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  43. GRB 250207B: MAXI/GSC detection
  44. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  45. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  46. GRB 250207A: Swift detection of a burst with optical counterpart
  47. GRB 250207A: Fermi GBM Final Real-time Localization
  48. GRB 250206A: Fermi GBM Final Real-time Localization
  49. EP250205a/GRB 250205A: Einstein Probe observation
  50. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  51. GRB 250205A: Swift/XRT detection
  52. GRB250205A: SVOM/VT optical afterglow detection
  53. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  54. GRB 250205A: SVOM detection of a burst
  55. Konus-Wind detection of GRB 250201A
  56. IPN triangulation of GRB 250201A
  57. Konus-Wind detection of GRB 250202B
  58. IPN triangulation of GRB 250204B (short/hard)
  59. IPN triangulation of GRB 250202B
  60. GRB 250204B: AstroSat CZTI detection of a short burst
  61. GRB 250204B: Fermi GBM Final Localization
  62. GRB 250129A: LCO late afterglow detection
  63. GRB 250204A: Fermi GBM Final Real-time Localization
  64. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  65. GRB 250202B: NuSTAR detection of the prompt emission
  66. GRB 250202C: GRBAlpha detection
  67. GRB 250202B: Fermi GBM Detection
  68. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 250129a: Liverpool Telescope optical follow-up
  70. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  71. GRB 250202C: Fermi GBM Final Real-time Localization
  72. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  73. LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate
  74. GRB 250202B: Fermi GBM Final Real-time Localization
  75. GRB 250202A: Fermi GBM Final Real-time Localization
  76. GRB 250201A: INTEGRAL SPI/ACS detection
  77. Konus-Wind detection of GRB 250129A
  78. GRB 250129A: 1.3m DFOT Optical observations
  79. GRB 250201A: Fermi GBM Final Real-time Localization
  80. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  81. GRB 250129A: optical photometry from Konkoly
  82. GRB 250128B: VLA possible radio detection
  83. GRB 250129a: Liverpool Telescope optical follow-up
  84. GRB 250129A: TNG NIR afterglow detection
  85. GRB 250129A: AKO Optical Afterglow Detection
  86. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  87. Ep250125A: 1.3m DFOT optical upper limit
  88. GRB 250129A: Skynet optical observations
  89. GRB 250128B: Gemini-North optical extended source detection
  90. GRB 250129A: Swift/UVOT Detection
  91. GRB 250129A: REM optical/NIR afterglow detection
  92. GRB 250129A: Early afterglow detection by LCO.
  93. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  94. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  95. GRB 250129A: Swift detection of a burst with an optical counterpart
  96. Swift GRB 250129A: Global MASTER-Net OT detection
  97. GRB 250128B: Swift detection of a short burst
  98. GRB 250128B: Fermi GBM Final Real-time Localization
  99. GRB 250127B: DDOTI Upper Limit on the Afterglow
  100. GRB 250127A: EP-FXT afterglow detection

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