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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"

14345 results found.

  1. GRB 250620C: Fermi GBM Final Real-time Localization
  2. GRB 250620B: Fermi GBM Final Real-time Localization
  3. GRB 250620A: Fermi GBM Final Real-time Localization
  4. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  5. GRB 250619B: Fermi GBM Final Real-time Localization
  6. GRB 250619A: Fermi GBM Final Real-time Localization
  7. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  8. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  9. GRB 250617B: Swift/UVOT Detection
  10. GRB 250617B: Kilonova-Catcher optical afterglow detection
  11. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  12. GRB 250617B: NUTTelA-TAO early time optical observations
  13. GRB 250617B: Fermi GBM Final Localization
  14. GRB 250617B: Ondrejov D50 optical afterglow detection
  15. GRB 250617B: Swift detection of a burst with an optical counterpart
  16. GRB 250617A: Fermi GBM Final Real-time Localization
  17. IPN triangulation of GRB 250612C (short/hard)
  18. EP#01709178975: Swift-XRT counterpart detection
  19. Konus-Wind detection of GRB 250615A / EP250615a
  20. GRB 250615A / EP250615a: AstroSat CZTI detection
  21. GRB 250615A: COLIBRÍ optical upper limit
  22. GRB 250615A: DDOTI Optical Upper Limit
  23. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  24. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  25. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  26. GRB 250615A: Swift detection of a burst
  27. GRID detection of GRB 250612C
  28. sb25061207: Mephisto optical upper limits
  29. IceCube alert 141029_8144692 retraction
  30. GRB 250614A: Fermi GBM Final Real-time Localization
  31. sb25061207: EP-FXT follow-up observation and afterglow candidate
  32. sb25061218: SVOM detection of a X-ray transient
  33. EP 250612a: AST3-3 Yaoan Optical Observation
  34. GRB 250612C: Fermi GBM Final Real-time Localization
  35. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  36. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  37. EP250612a: Einstein Probe detection of an X-ray transient
  38. sb25061207: SVOM detection of a X-ray transient
  39. EP250610a: continuous follow-up observations with EP-FXT
  40. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  41. Fermi GBM Sub-Threshold Detection of GRB 250610B
  42. GRB 250610B: Swift/UVOT Detection
  43. EP250610a: Liverpool Telescope optical upper limits
  44. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  45. GRB 250610B: Swift-XRT counterpart detection
  46. GRB 250610B: LT detection of the optical counterpart
  47. GRB 250610C: Fermi GBM Final Real-time Localization
  48. GRB 250610B: SVOM detection of a long burst
  49. GRB 250610A: Fermi GBM Final Real-time Localization
  50. EP250610a: Swift-XRT counterpart detection
  51. EP250610a: Einstein Probe detection of an X-ray transient
  52. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  53. GRB 250609A: Fermi GBM Final Real-time Localization
  54. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  55. GRB 250607A: Fermi GBM Final Localization
  56. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  57. GRB 250606A: Fermi GBM Final Real-time Localization
  58. GRB 250602A: GECAM detection
  59. GRB 250605A: LT optical observations
  60. GRB 250605A: Swift detection of a burst
  61. Konus-Wind detection of GRB 250601A
  62. IPN triangulation of GRB 250404B
  63. IPN triangulation of GRB 250529A
  64. GRB 250601A: PRIME H band upper limit.
  65. GRB 250601A: PRIME J band upper limit.
  66. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  67. GRB 250602A: Fermi-LAT detection
  68. GRB 250601A: Swift/XRT candidate afterglow
  69. GRB 250602A: Fermi GBM Final Real-time Localization
  70. GRB 250601A: Fermi GBM Final Real-time Localization
  71. EP#01709177494: SVOM/VT optical observations
  72. GRB 250531A: Fermi GBM Final Real-time Localization
  73. EP#01709177494: Swift-XRT counterpart detection of known source
  74. GRB 250530C: BOOTES-7 optical upper limit
  75. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  76. GRB 250530C: Swift detection of a burst
  77. GRB 250530A: EP-FXT counterpart detection
  78. GRB 250530A: SVOM/VT optical upper limit
  79. GRB 250530B: Fermi GBM Final Real-time Localization
  80. GRB 250530A: Swift-XRT counterpart detection
  81. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  82. GRB 250530A: SVOM detection of a burst
  83. GRB 250527D: CALET Gamma-Ray Burst Monitor detection
  84. EP J1350.0-8622: EP-FXT follow-up observation
  85. GRB 250529B: Fermi GBM Final Real-time Localization
  86. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  87. GRB 250529A: Fermi GBM Final Real-time Localization
  88. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  89. GRB 250520A: Gemini-South optical afterglow detection
  90. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  91. GRB 250527A: Fermi GBM Final Localization
  92. EP250526a: Einstein Probe detection of a fast X-ray transient
  93. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  94. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  95. GRB 250520A: 3 GHz MeerKAT Detection
  96. GRB 250521A: GRBAlpha detection
  97. GRB 250520A: GRBAlpha detection
  98. GRB 250523A: Fermi GBM Final Real-time Localization
  99. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  100. GRB 250522B: Fermi GBM Final Localization

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