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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"

18572 results found.

  1. GRB 250221A: Swift detection of a burst with an optical counterpart
  2. Swift GRB250221.15: Global MASTER-Net OT detection
  3. Swift GRB250221.15: Global MASTER-Net observations report
  4. GRB 250219A: Swift/UVOT Upper Limits
  5. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  6. GRB 250219A: 1.6m Mephisto optical upper limits
  7. GRB 250219A: SVOM/VT optical counterpart
  8. GRB 250219A: Swift-XRT observations
  9. GRB 250219A: Swift ToO observations
  10. GRB 250217C: Swift-XRT observations
  11. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  12. GRB 250217C: Tiled Swift observations
  13. IPN triangulation of GRB 250217C (short)
  14. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  15. SVOM/sb25021804: SVOM detection of a long X-ray transient
  16. GRB 250213A: Swift-XRT observations
  17. GRB 250215A / EP250215a: LCO detection of the afterglow
  18. GRB 250215A: Swift/UVOT Upper Limits
  19. GRB 250215A: Fermi GBM Observation
  20. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  21. GRB 250215A: Swift-XRT refined Analysis
  22. GRB 250213A: Swift ToO observations
  23. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  24. GRB 250211A: Swift ToO observations
  25. GRB 250207A: Fermi GBM Observation
  26. Konus-Wind detection of GRB 250207A
  27. GRB 250207A: Skynet optical afterglow observations
  28. GRB 250207A: 1.3m DFOT Optical observations
  29. GRB 250206A: Swift-XRT observations
  30. GRB 250129A: GRANDMA Continued Afterglow Detection
  31. GRB 250207A: Swift-BAT refined analysis
  32. GRB 250205A: 1.3m DFOT optical upper limit
  33. GRB 250206A: Tiled Swift observations
  34. GRB 250206A: Fermi-LAT detection
  35. GRB 250207B: Swift-XRT observations
  36. EP250207a: EP-WXT detection and XRT follow-up observation
  37. GRB 250207A: Swift-XRT refined Analysis
  38. GRB 250207A: Enhanced Swift-XRT position
  39. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  40. GRB 250207A: REM IR afterglow detection
  41. GRB 250207A: FRAM-Auger optical detection
  42. GRB 250207B: Tiled Swift observations
  43. GRB 250207A: REM optical afterglow detection
  44. GRB 250207A: Swift/UVOT Detection
  45. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  46. GRB 250207A: Swift detection of a burst with optical counterpart
  47. GRB 250205A: Fermi GBM Observation
  48. GRB 250205A: Swift/UVOT Upper Limits
  49. GRB 250205A: Swift/XRT detection
  50. IPN triangulation of GRB 250201A
  51. GRB 250129A: Swift-BAT refined analysis
  52. IPN triangulation of GRB 250204B (short/hard)
  53. IPN triangulation of GRB 250202B
  54. GRB 250129A: LCO late afterglow detection
  55. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  56. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  57. GRB 250129A: SVOM/C-GFT optical observations
  58. Swift GRB250129A: MASTER 4 days observations report
  59. Konus-Wind detection of GRB 250129A
  60. GRB 250129A: 1.3m DFOT Optical observations
  61. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  62. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  63. GRB 250129A: COLIBRÍ Optical Observations
  64. GRB 250129A: TNG NIR afterglow detection
  65. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  66. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  67. GRB 250128B: VLA radio upper limit
  68. Ep250125A: 1.3m DFOT optical upper limit
  69. GRB 250129A: Skynet optical observations
  70. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  71. GRB 250129A: Swift-XRT refined Analysis
  72. GRB 250128B: TNG optical upper limit
  73. GRB 250129A: Swift/UVOT Detection
  74. GRB 250127A: CrAO and Terskol optical upper limits
  75. GRB 250129A: Enhanced Swift-XRT position
  76. GRB 250128B: NOT optical upper limit
  77. GRB 250129A: REM optical/NIR afterglow detection
  78. GRB 250129A: Early afterglow detection by LCO.
  79. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  80. GRB 250129A: LCO optical observations
  81. GRB 250129A: GOTO optical observations show brightening afterglow
  82. Swift GRB 250129A: Global MASTER-Net observations report
  83. GRB 250128B: Enhanced Swift-XRT position
  84. GRB 250129A: Swift detection of a burst with an optical counterpart
  85. Swift GRB 250129A: Global MASTER-Net OT detection
  86. GRB 250128B: Swift-XRT refined Analysis
  87. GRB 250128B: Fermi GBM Observation
  88. GRB 250128B: GOTO optical upper limit
  89. Swift GRB 250128B: Global MASTER-Net observations report
  90. EP250125a: Upper limits from Swift/BAT-GUANO
  91. GRB 250128B: LCO optical observations
  92. GRB 250128B: Swift detection of a short burst
  93. GRB 250127A: Swift-XRT observations
  94. GRB 250127A: EP-FXT afterglow detection
  95. GRB 250117A: Fermi GBM Observation
  96. GRB 250127A: SVOM/VT upper limit
  97. IPN triangulation of GRB 250119C
  98. GRB 250127A: Swift ToO observations
  99. GRB 250118A: Fermi GBM Observation
  100. EP250125a: REM optical counterpart detection

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