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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"

28115 results found.

  1. EP250215a / GRB 250215A: AstroSat CZTI detection
  2. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  3. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  4. GRB 250215A: Fermi GBM Final Real-time Localization
  5. EP250207b: Xinglong optical upper limit
  6. GRB 250213A: Swift ToO observations
  7. GRB 250214A: Fermi GBM Final Real-time Localization
  8. EP250212a: Xinglong optical upper limit
  9. GRB 250213A: SVOM detection of a burst
  10. GRB 250205A: VIRT Optical Upper Limit
  11. GRB 250205A: Leavitt Observatory optical upper limit
  12. GRB 250210A: GRBAlpha detection
  13. EP250207B: Chandra localization of the X-ray counterpart
  14. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  15. EP250212a: Liverpool Telescope optical upper limits
  16. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  17. GRB 250211A: Swift ToO observations
  18. GRB 250212A: Fermi GBM Final Real-time Localization
  19. GRB 250205A / EP250205A: radio detection with the VLA
  20. IceCube-250207A: One candidate from the Zwicky Transient Facility
  21. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  22. Konus-Wind detection of GRB 250207A
  23. Konus-Wind detection of GRB 250206A
  24. EP250207b: Liverpool Telescope possible optical counterpart
  25. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  26. GRB 250207A: Skynet optical afterglow observations
  27. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  28. GRB 241128A: VIRT Optical Upper Limit
  29. GRB 250210A: INTEGRAL SPI-ACS detection
  30. GRB 250210A: AstroSat CZTI detection
  31. EP250207b: a new X-ray transient detected by Einstein Probe
  32. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  33. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  34. GRB 250210A: Fermi GBM Final Real-time Localization
  35. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  36. GRB 250204B: GRBAlpha detection
  37. GRB 250204A: GRBAlpha detection
  38. GRB 250207A: 1.3m DFOT Optical observations
  39. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  40. GRB 250206A: Swift-XRT observations
  41. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  42. GRB 250129A: GRANDMA Continued Afterglow Detection
  43. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  44. GRB 250205A: 1.3m DFOT optical upper limit
  45. GRB 250206A: Tiled Swift observations
  46. GRB 250206A: EIRSAT-1 GMOD Detection
  47. GRB 250206A: Fermi-LAT detection
  48. GRB 250207B: Swift-XRT observations
  49. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  50. GRB 250208A: Fermi GBM Final Real-time Localization
  51. EP250207a: EP-WXT detection and XRT follow-up observation
  52. GRB 250207A: Swift-XRT refined Analysis
  53. GRB 250207A: Enhanced Swift-XRT position
  54. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  55. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  56. GRB 250207A: REM IR afterglow detection
  57. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  58. GRB 250207A: FRAM-Auger optical detection
  59. GRB 250207B: Tiled Swift observations
  60. Konus-Wind detection of GRB 250204B
  61. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  62. GRB 250207A: REM optical afterglow detection
  63. GRB 250207A: Swift/UVOT Detection
  64. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  65. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  66. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  67. GRB 250207B: MAXI/GSC detection
  68. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  69. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  70. GRB 250207A: Swift detection of a burst with optical counterpart
  71. GRB 250207A: Fermi GBM Final Real-time Localization
  72. GRB 250206A: Fermi GBM Final Real-time Localization
  73. GRB 250205A: Fermi GBM Observation
  74. GRB 250205A: REM NIR upper limit
  75. GRB 250205A: Swift/UVOT Upper Limits
  76. EP250205a/GRB 250205A: Einstein Probe observation
  77. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  78. GRB 250205A: Swift/XRT detection
  79. GRB250205A: SVOM/VT optical afterglow detection
  80. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  81. GRB 250205A: SVOM detection of a burst
  82. Konus-Wind detection of GRB 250201A
  83. IPN triangulation of GRB 250201A
  84. Konus-Wind detection of GRB 250202B
  85. IPN triangulation of GRB 250204B (short/hard)
  86. IPN triangulation of GRB 250202B
  87. GRB 250204B: AstroSat CZTI detection of a short burst
  88. GRB 250204B: Fermi GBM Final Localization
  89. GRB 250129A: LCO late afterglow detection
  90. GRB 250204A: Fermi GBM Final Real-time Localization
  91. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  92. GRB 250202B: NuSTAR detection of the prompt emission
  93. GRB 250202C: GRBAlpha detection
  94. GRB 250202B: Fermi GBM Detection
  95. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 250129a: Liverpool Telescope optical follow-up
  97. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  98. GRB 250202C: Fermi GBM Final Real-time Localization
  99. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  100. LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate

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