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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"

28124 results found.

  1. GRB 250620A: AstroSat CZTI detection
  2. GRB 241018A: Maidanak optical observations
  3. GRB 250620C: AstroSat CZTI detection
  4. GRB 250624A: Fermi GBM Final Real-time Localization
  5. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  6. GRB 250623A: Fermi GBM Final Real-time Localization
  7. GRB 250521A: VZLUSAT-2 detection
  8. Konus-Wind detection of GRB 250620C
  9. IPN triangulation of GRB 250620C (long/bright)
  10. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  11. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  12. GRB 250621A: Fermi GBM Final Real-time Localization
  13. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  14. GRB 250620C: Fermi GBM Final Real-time Localization
  15. GRB 250620B: Fermi GBM Final Real-time Localization
  16. GRB 250620A: Fermi GBM Final Real-time Localization
  17. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  18. GRB 250617B: Nickel telescope optical observations
  19. GRB 250619B: Fermi GBM Final Real-time Localization
  20. GRB 250615A: Kilonova-Catcher optical upper limits
  21. GRB 250619A: Fermi GBM Final Real-time Localization
  22. GRB 250617B: Assy AZT-20 Optical Observations
  23. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  24. GRB 250615A/EP250615a: FTW optical and NIR observations
  25. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  26. GRB 250617B: Swift/UVOT Detection
  27. GRB 250617B: Kilonova-Catcher optical afterglow detection
  28. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  29. GRB 250617B: NOT NIR observations of the afterglow
  30. GRB 250617B: Swift-XRT refined Analysis
  31. GRB 250617B: SVOM/VT optical observation
  32. GRB 250617B: NUTTelA-TAO early time optical observations
  33. GRB 250617B: GOTO optical upper limit
  34. GRB 250617B: Enhanced Swift-XRT position
  35. GRB 250617B: Fermi GBM Final Localization
  36. GRB 250617B: Ondrejov D50 optical afterglow detection
  37. GRB 250617B: Swift detection of a burst with an optical counterpart
  38. GRB 250617A: Fermi GBM Final Real-time Localization
  39. IPN triangulation of GRB 250612C (short/hard)
  40. EP#01709178975: Swift-XRT counterpart detection
  41. Konus-Wind detection of GRB 250615A / EP250615a
  42. GRB 250615A / EP250615a: AstroSat CZTI detection
  43. GRB 250615A: COLIBRÍ optical upper limit
  44. GRB 250615A: DDOTI Optical Upper Limit
  45. GRB 250615A: Swift/UVOT Upper Limits
  46. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  47. GRB 250615A: Swift-XRT refined Analysis
  48. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  49. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  50. GRB 250615A: Enhanced Swift-XRT position
  51. GRB 250615A: Prompt enhanced Swift-XRT position
  52. GRB 250615A: Swift detection of a burst
  53. GRID detection of GRB 250612C
  54. sb25061207: Mephisto optical upper limits
  55. IceCube alert 141029_8144692 retraction
  56. GRB 250614A: Fermi GBM Final Real-time Localization
  57. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  58. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  59. sb25061218: Swift-XRT observations
  60. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  61. sb25061207: EP-FXT follow-up observation and afterglow candidate
  62. sb25061218: SVOM detection of a X-ray transient
  63. sb25061207: Swift-XRT observations
  64. EP 250612a: AST3-3 Yaoan Optical Observation
  65. GRB 250610B: Swift-XRT refined Analysis
  66. GRB 250612C: Fermi GBM Final Real-time Localization
  67. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  68. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  69. EP250612a: Einstein Probe detection of an X-ray transient
  70. sb25061207: SVOM detection of a X-ray transient
  71. EP250610a: continuous follow-up observations with EP-FXT
  72. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  73. Fermi GBM Sub-Threshold Detection of GRB 250610B
  74. GRB 250610B: Swift/UVOT Detection
  75. EP250610A: Swift/UVOT Upper limits
  76. EP250610a: TNG NIR upper limit
  77. GRB 250610B: REM optical/NIR observations
  78. EP250610a: Liverpool Telescope optical upper limits
  79. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  80. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  81. GRB 250610B: Swift-XRT counterpart detection
  82. GRB 250610B: LT detection of the optical counterpart
  83. GRB 250610B: OHP/T120 optical counterpart candidate
  84. GRB 250610C: Fermi GBM Final Real-time Localization
  85. GRB 250610B: SVOM detection of a long burst
  86. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  87. GRB 250610A: Fermi GBM Final Real-time Localization
  88. EP250610a: SVOM/VT optical upper limit
  89. EP250610a: REM optical/NIR observations
  90. EP250610a: Swift-XRT counterpart detection
  91. EP250610a: Einstein Probe detection of an X-ray transient
  92. GRB 250605A: Swift/UVOT Upper Limits
  93. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  94. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  95. GRB 250527C: CrAO Optical Upper Limit
  96. GRB 250609A: Fermi GBM Final Real-time Localization
  97. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  98. GRB 250607A: Fermi GBM Final Localization
  99. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  100. GRB 250605A: SVOM/VT optical upper limit

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