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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"

35424 results found.

  1. GRB 250206A: Fermi GBM Observation
  2. GRB 250205A / EP250205A: radio detection with the VLA
  3. Konus-Wind detection of GRB 250207A
  4. Konus-Wind detection of GRB 250206A
  5. GRB 250210A: SVOM/GRM observation of a long burst
  6. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  7. GRB 250207A: Skynet optical afterglow observations
  8. GRB 241128A: VIRT Optical Upper Limit
  9. EP250207A: Upper limits from Fermi-GBM Observations
  10. GRB 250210A: INTEGRAL SPI-ACS detection
  11. GRB 250210A: AstroSat CZTI detection
  12. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  13. Fermi GRB 250210A: Global MASTER-Net observations report
  14. GRB 250210A: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  16. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 250204B: GRBAlpha detection
  18. GRB 250204A: GRBAlpha detection
  19. GRB 250207A: 1.3m DFOT Optical observations
  20. GRB 250206A: Swift-XRT observations
  21. GRB 250129A: GRANDMA Continued Afterglow Detection
  22. GRB 250207A: Swift-BAT refined analysis
  23. GRB 250205A: 1.3m DFOT optical upper limit
  24. GRB 250206A: Tiled Swift observations
  25. GRB 250206A: EIRSAT-1 GMOD Detection
  26. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  27. GRB 250206A: Fermi-LAT detection
  28. GRB 250207B: Swift-XRT observations
  29. GRB 250208A: Fermi GBM Final Real-time Localization
  30. GRB 250207A: Swift-XRT refined Analysis
  31. GRB 250207A: Enhanced Swift-XRT position
  32. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  33. GRB 250207A: REM IR afterglow detection
  34. GRB 250207A: FRAM-Auger optical detection
  35. GRB 250207B: Tiled Swift observations
  36. Konus-Wind detection of GRB 250204B
  37. GRB 250207A: REM optical afterglow detection
  38. GRB 250207A: Swift/UVOT Detection
  39. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  40. GRB 250129A: Continued AbAO and Mondy optical observations
  41. GRB 250207B: MAXI/GSC detection
  42. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  43. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  44. GRB 250207A: Swift detection of a burst with optical counterpart
  45. GRB 250207A: Fermi GBM Final Real-time Localization
  46. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  47. GRB 250206A: Fermi GBM Final Real-time Localization
  48. GRB 250205A: Fermi GBM Observation
  49. GRB 250205A: REM NIR upper limit
  50. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  51. GRB 250205A: Swift/UVOT Upper Limits
  52. EP250205a/GRB 250205A: correction to the source localization
  53. EP250205a/GRB 250205A: Einstein Probe observation
  54. GRB 250127C: SVOM/GRM observation of a burst
  55. GRB 250204B: SVOM/GRM observation of a likely short burst
  56. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  57. GRB 250205A: Swift/XRT detection
  58. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  59. GRB250205A: SVOM/VT optical afterglow detection
  60. GRB 250205A: GOTO optical upper limits
  61. GRB 250205A: OHP/T193 optical counterpart candidate
  62. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  63. GRB 250205A: SVOM detection of a burst
  64. Konus-Wind detection of GRB 250201A
  65. IPN triangulation of GRB 250201A
  66. Konus-Wind detection of GRB 250202B
  67. GRB 250129A: Swift-BAT refined analysis
  68. EP 250108A: Upper limits from Fermi-GBM Observations
  69. IPN triangulation of GRB 250204B (short/hard)
  70. IPN triangulation of GRB 250202B
  71. GRB 250204B: AstroSat CZTI detection of a short burst
  72. GRB 250204B: Fermi GBM Final Localization
  73. GRB 250129A: LCO late afterglow detection
  74. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  75. GRB 250204A: Fermi GBM Final Real-time Localization
  76. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  77. GRB 250202B: NuSTAR detection of the prompt emission
  78. GRB 250202C: GRBAlpha detection
  79. GRB 250202B: Fermi GBM Detection
  80. GRB 250129a: Liverpool Telescope optical follow-up
  81. GRB 240129A: further SAO RAS optical observations
  82. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  83. GRB 250202C: Fermi GBM Final Real-time Localization
  84. GRB 250129A: SVOM/C-GFT optical observations
  85. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  86. GRB 250202B: Fermi GBM Final Real-time Localization
  87. Swift GRB250129A: MASTER 4 days observations report
  88. GRB 250202A: Fermi GBM Final Real-time Localization
  89. GRB 250201A: INTEGRAL SPI/ACS detection
  90. Konus-Wind detection of GRB 250129A
  91. GRB 250129A: 1.3m DFOT Optical observations
  92. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  93. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  94. GRB 250201A: Fermi GBM Final Real-time Localization
  95. GRB 250129A: Skynet Continued Optical Observations
  96. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  97. GRB 250129A: SAO RAS optical observations
  98. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  99. GRB 250129A: optical photometry from Konkoly
  100. GRB 250129A: COLIBRÍ Optical Observations

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