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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"

27817 results found.

  1. EP250207b: Xinglong optical upper limit
  2. GRB 250213A: Swift ToO observations
  3. GRB 250214A: Fermi GBM Final Real-time Localization
  4. EP250212a: Xinglong optical upper limit
  5. GRB 250213A: SVOM detection of a burst
  6. GRB 250205A: VIRT Optical Upper Limit
  7. GRB 250205A: Leavitt Observatory optical upper limit
  8. GRB 250210A: GRBAlpha detection
  9. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  10. EP250212a: Liverpool Telescope optical upper limits
  11. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  12. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  13. GRB 250211A: Swift ToO observations
  14. GRB 250212A: Fermi GBM Final Real-time Localization
  15. GRB 250207A: Fermi GBM Observation
  16. GRB 250205A / EP250205A: radio detection with the VLA
  17. IceCube-250207A: One candidate from the Zwicky Transient Facility
  18. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  19. Konus-Wind detection of GRB 250207A
  20. Konus-Wind detection of GRB 250206A
  21. EP250207b: Liverpool Telescope possible optical counterpart
  22. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  23. GRB 250207A: Skynet optical afterglow observations
  24. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  25. GRB 241128A: VIRT Optical Upper Limit
  26. GRB 250210A: INTEGRAL SPI-ACS detection
  27. GRB 250210A: AstroSat CZTI detection
  28. EP250207b: a new X-ray transient detected by Einstein Probe
  29. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  30. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  31. GRB 250210A: Fermi GBM Final Real-time Localization
  32. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  33. GRB 250204B: GRBAlpha detection
  34. GRB 250204A: GRBAlpha detection
  35. GRB 250207A: 1.3m DFOT Optical observations
  36. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  37. GRB 250206A: Swift-XRT observations
  38. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  39. GRB 250129A: GRANDMA Continued Afterglow Detection
  40. GRB 250207A: Swift-BAT refined analysis
  41. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  42. GRB 250205A: 1.3m DFOT optical upper limit
  43. GRB 250206A: Tiled Swift observations
  44. GRB 250206A: EIRSAT-1 GMOD Detection
  45. GRB 250206A: Fermi-LAT detection
  46. GRB 250207B: Swift-XRT observations
  47. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  48. GRB 250208A: Fermi GBM Final Real-time Localization
  49. EP250207a: EP-WXT detection and XRT follow-up observation
  50. GRB 250207A: Swift-XRT refined Analysis
  51. GRB 250207A: Enhanced Swift-XRT position
  52. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  53. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  54. GRB 250207A: REM IR afterglow detection
  55. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  56. GRB 250207A: FRAM-Auger optical detection
  57. GRB 250207B: Tiled Swift observations
  58. Konus-Wind detection of GRB 250204B
  59. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB 250207A: REM optical afterglow detection
  61. GRB 250207A: Swift/UVOT Detection
  62. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  63. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  64. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  65. GRB 250207B: MAXI/GSC detection
  66. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  67. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  68. GRB 250207A: Swift detection of a burst with optical counterpart
  69. GRB 250207A: Fermi GBM Final Real-time Localization
  70. GRB 250206A: Fermi GBM Final Real-time Localization
  71. GRB 250205A: Fermi GBM Observation
  72. GRB 250205A: Swift/UVOT Upper Limits
  73. EP250205a/GRB 250205A: Einstein Probe observation
  74. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  75. GRB 250205A: Swift/XRT detection
  76. GRB250205A: SVOM/VT optical afterglow detection
  77. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  78. GRB 250205A: SVOM detection of a burst
  79. Konus-Wind detection of GRB 250201A
  80. IPN triangulation of GRB 250201A
  81. Konus-Wind detection of GRB 250202B
  82. GRB 250129A: Swift-BAT refined analysis
  83. IPN triangulation of GRB 250204B (short/hard)
  84. IPN triangulation of GRB 250202B
  85. GRB 250204B: AstroSat CZTI detection of a short burst
  86. GRB 250204B: Fermi GBM Final Localization
  87. GRB 250129A: LCO late afterglow detection
  88. GRB 250204A: Fermi GBM Final Real-time Localization
  89. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  90. GRB 250202B: NuSTAR detection of the prompt emission
  91. GRB 250202C: GRBAlpha detection
  92. GRB 250202B: Fermi GBM Detection
  93. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  94. GRB 250129a: Liverpool Telescope optical follow-up
  95. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  96. GRB 250202C: Fermi GBM Final Real-time Localization
  97. GRB 250129A: SVOM/C-GFT optical observations
  98. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  99. LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate
  100. GRB 250202B: Fermi GBM Final Real-time Localization

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