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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"

18635 results found.

  1. GRB 250207B: Swift-XRT observations
  2. EP250207a: EP-WXT detection and XRT follow-up observation
  3. GRB 250207A: Swift-XRT refined Analysis
  4. GRB 250207A: Enhanced Swift-XRT position
  5. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  6. GRB 250207A: REM IR afterglow detection
  7. GRB 250207A: FRAM-Auger optical detection
  8. GRB 250207B: Tiled Swift observations
  9. GRB 250207A: REM optical afterglow detection
  10. GRB 250207A: Swift/UVOT Detection
  11. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  12. GRB 250207A: Swift detection of a burst with optical counterpart
  13. GRB 250205A: Fermi GBM Observation
  14. GRB 250205A: Swift/UVOT Upper Limits
  15. GRB 250205A: Swift/XRT detection
  16. IPN triangulation of GRB 250201A
  17. GRB 250129A: Swift-BAT refined analysis
  18. IPN triangulation of GRB 250204B (short/hard)
  19. IPN triangulation of GRB 250202B
  20. GRB 250129A: LCO late afterglow detection
  21. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  22. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  23. GRB 250129A: SVOM/C-GFT optical observations
  24. Swift GRB250129A: MASTER 4 days observations report
  25. Konus-Wind detection of GRB 250129A
  26. GRB 250129A: 1.3m DFOT Optical observations
  27. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  28. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  29. GRB 250129A: COLIBRÍ Optical Observations
  30. GRB 250129A: TNG NIR afterglow detection
  31. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  32. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  33. GRB 250128B: VLA radio upper limit
  34. Ep250125A: 1.3m DFOT optical upper limit
  35. GRB 250129A: Skynet optical observations
  36. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  37. GRB 250129A: Swift-XRT refined Analysis
  38. GRB 250128B: TNG optical upper limit
  39. GRB 250129A: Swift/UVOT Detection
  40. GRB 250127A: CrAO and Terskol optical upper limits
  41. GRB 250129A: Enhanced Swift-XRT position
  42. GRB 250128B: NOT optical upper limit
  43. GRB 250129A: REM optical/NIR afterglow detection
  44. GRB 250129A: Early afterglow detection by LCO.
  45. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  46. GRB 250129A: LCO optical observations
  47. GRB 250129A: GOTO optical observations show brightening afterglow
  48. Swift GRB 250129A: Global MASTER-Net observations report
  49. GRB 250128B: Enhanced Swift-XRT position
  50. GRB 250129A: Swift detection of a burst with an optical counterpart
  51. Swift GRB 250129A: Global MASTER-Net OT detection
  52. GRB 250128B: Swift-XRT refined Analysis
  53. GRB 250128B: Fermi GBM Observation
  54. GRB 250128B: GOTO optical upper limit
  55. Swift GRB 250128B: Global MASTER-Net observations report
  56. EP250125a: Upper limits from Swift/BAT-GUANO
  57. GRB 250128B: LCO optical observations
  58. GRB 250128B: Swift detection of a short burst
  59. GRB 250127A: Swift-XRT observations
  60. GRB 250127A: EP-FXT afterglow detection
  61. GRB 250117A: Fermi GBM Observation
  62. GRB 250127A: SVOM/VT upper limit
  63. IPN triangulation of GRB 250119C
  64. GRB 250127A: Swift ToO observations
  65. GRB 250118A: Fermi GBM Observation
  66. EP250125a: REM optical counterpart detection
  67. GRB 250119C: Fermi GBM Observation
  68. EP250125a: Swift/XRT detection of a fading counterpart
  69. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  70. IPN triangulation of GRB 250118B
  71. Konus-Wind detection of GRB 250119B
  72. IPN triangulation of GRB 250119B
  73. Improved IPN triangulation of GRB 250107C
  74. GRB 250114A: Swift-BAT refined analysis
  75. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  76. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  77. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  78. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  79. Konus-Wind detection of GRB 250117A
  80. IPN triangulation of GRB 250117A (short)
  81. GRB 250117A: SVOM/GRM observation of a short burst
  82. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  83. Swift Trigger 1282245 is not a GRB
  84. GRB 250114B: Swift-XRT afterglow detection
  85. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  86. IPN triangulation of GRB 250113A
  87. GRB 250114B: Swift-XRT observations
  88. GRB 250114A: LCO optical counterpart detection.
  89. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  90. GRB 250114A: Swift-XRT refined Analysis
  91. GRB 250114A: LCOGT optical afterglow i-band detection
  92. GRB 250114B: Swift ToO observations
  93. EP250111a: SAO RAS optical upper limit
  94. GRB 250114A: Enhanced Swift-XRT position
  95. GRB 250114A: REM detection of the optical and NIR counterpart
  96. Swift GRB250114A: Global MASTER-Net OT detection
  97. GRB 250114A: LCO optical observations
  98. GRB 250114A: TRT optical observations
  99. Swift GRB 250114A: Global MASTER-Net observations report
  100. GRB 250114A: Swift detection of a burst with an optical counterpart

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