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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"

37283 results found.

  1. Fermi GRB 250214A: Global MASTER-Net observations report
  2. GRB 250213A: Swift ToO observations
  3. GRB 250214A: Fermi GBM Final Real-time Localization
  4. GRB 250213A: SVOM detection of a burst
  5. GRB 250205A: VIRT Optical Upper Limit
  6. GRB 250205A: Leavitt Observatory optical upper limit
  7. GRB 250210A: GRBAlpha detection
  8. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  9. Fermi GRB 250212A: Global MASTER-Net observations report
  10. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  11. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  12. GRB 250211B: A long GRB detected by INTEGRAL
  13. GRB 250211A: Swift ToO observations
  14. GRB 250212A: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  16. GRB 250207A: Fermi GBM Observation
  17. GRB 250206A: Fermi GBM Observation
  18. GRB 250205A / EP250205A: radio detection with the VLA
  19. IceCube-250207A: One candidate from the Zwicky Transient Facility
  20. Konus-Wind detection of GRB 250207A
  21. Konus-Wind detection of GRB 250206A
  22. GRB 250210A: SVOM/GRM observation of a long burst
  23. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  24. GRB 250207A: Skynet optical afterglow observations
  25. GRB 241128A: VIRT Optical Upper Limit
  26. EP250207A: Upper limits from Fermi-GBM Observations
  27. GRB 250210A: INTEGRAL SPI-ACS detection
  28. GRB 250210A: AstroSat CZTI detection
  29. EP250207b: a new X-ray transient detected by Einstein Probe
  30. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  31. Fermi GRB 250210A: Global MASTER-Net observations report
  32. GRB 250210A: Fermi GBM Final Real-time Localization
  33. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  34. GRB 250204B: GRBAlpha detection
  35. GRB 250204A: GRBAlpha detection
  36. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  37. GRB 250207A: 1.3m DFOT Optical observations
  38. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  39. GRB 250206A: Swift-XRT observations
  40. GRB 250129A: GRANDMA Continued Afterglow Detection
  41. GRB 250207A: Swift-BAT refined analysis
  42. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  43. GRB 250205A: 1.3m DFOT optical upper limit
  44. GRB 250206A: Tiled Swift observations
  45. GRB 250206A: EIRSAT-1 GMOD Detection
  46. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  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. GRB 250207A: Swift-XRT refined Analysis
  52. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  53. GRB 250207A: Enhanced Swift-XRT position
  54. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  55. GRB 250207A: REM IR afterglow detection
  56. GRB 250207A: FRAM-Auger optical detection
  57. GRB 250207B: Tiled Swift observations
  58. Konus-Wind detection of GRB 250204B
  59. GRB 250207A: REM optical afterglow detection
  60. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  61. GRB 250207A: Swift/UVOT Detection
  62. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  63. GRB 250129A: Continued AbAO and Mondy optical observations
  64. GRB 250207B: MAXI/GSC detection
  65. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  66. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  67. GRB 250207A: Swift detection of a burst with optical counterpart
  68. GRB 250207A: Fermi GBM Final Real-time Localization
  69. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  70. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  71. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  72. GRB 250206A: Fermi GBM Final Real-time Localization
  73. GRB 250205A: Fermi GBM Observation
  74. GRB 250205A: REM NIR upper limit
  75. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  76. GRB 250205A: Swift/UVOT Upper Limits
  77. EP250205a/GRB 250205A: correction to the source localization
  78. EP250205a/GRB 250205A: Einstein Probe observation
  79. GRB 250127C: SVOM/GRM observation of a burst
  80. GRB 250204B: SVOM/GRM observation of a likely short burst
  81. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  82. GRB 250205A: Swift/XRT detection
  83. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  84. GRB250205A: SVOM/VT optical afterglow detection
  85. GRB 250205A: GOTO optical upper limits
  86. GRB 250205A: OHP/T193 optical counterpart candidate
  87. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  88. GRB 250205A: SVOM detection of a burst
  89. Konus-Wind detection of GRB 250201A
  90. IPN triangulation of GRB 250201A
  91. Konus-Wind detection of GRB 250202B
  92. GRB 250129A: Swift-BAT refined analysis
  93. EP 250108A: Upper limits from Fermi-GBM Observations
  94. IPN triangulation of GRB 250204B (short/hard)
  95. IPN triangulation of GRB 250202B
  96. GRB 250204B: AstroSat CZTI detection of a short burst
  97. GRB 250204B: Fermi GBM Final Localization
  98. GRB 250129A: LCO late afterglow detection
  99. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  100. GRB 250204A: Fermi GBM Final Real-time Localization

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