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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"

18633 results found.

  1. GRB 250207A: Swift-XRT refined Analysis
  2. GRB 250207A: Enhanced Swift-XRT position
  3. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  4. GRB 250207A: REM IR afterglow detection
  5. GRB 250207A: FRAM-Auger optical detection
  6. GRB 250207B: Tiled Swift observations
  7. GRB 250207A: REM optical afterglow detection
  8. GRB 250207A: Swift/UVOT Detection
  9. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  10. GRB 250207A: Swift detection of a burst with optical counterpart
  11. GRB 250205A: Fermi GBM Observation
  12. GRB 250205A: Swift/UVOT Upper Limits
  13. GRB 250205A: Swift/XRT detection
  14. IPN triangulation of GRB 250201A
  15. GRB 250129A: Swift-BAT refined analysis
  16. IPN triangulation of GRB 250204B (short/hard)
  17. IPN triangulation of GRB 250202B
  18. GRB 250129A: LCO late afterglow detection
  19. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  20. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  21. GRB 250129A: SVOM/C-GFT optical observations
  22. Swift GRB250129A: MASTER 4 days observations report
  23. Konus-Wind detection of GRB 250129A
  24. GRB 250129A: 1.3m DFOT Optical observations
  25. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  26. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  27. GRB 250129A: COLIBRÍ Optical Observations
  28. GRB 250129A: TNG NIR afterglow detection
  29. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  30. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  31. GRB 250128B: VLA radio upper limit
  32. Ep250125A: 1.3m DFOT optical upper limit
  33. GRB 250129A: Skynet optical observations
  34. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  35. GRB 250129A: Swift-XRT refined Analysis
  36. GRB 250128B: TNG optical upper limit
  37. GRB 250129A: Swift/UVOT Detection
  38. GRB 250127A: CrAO and Terskol optical upper limits
  39. GRB 250129A: Enhanced Swift-XRT position
  40. GRB 250128B: NOT optical upper limit
  41. GRB 250129A: REM optical/NIR afterglow detection
  42. GRB 250129A: Early afterglow detection by LCO.
  43. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  44. GRB 250129A: LCO optical observations
  45. GRB 250129A: GOTO optical observations show brightening afterglow
  46. Swift GRB 250129A: Global MASTER-Net observations report
  47. GRB 250128B: Enhanced Swift-XRT position
  48. GRB 250129A: Swift detection of a burst with an optical counterpart
  49. Swift GRB 250129A: Global MASTER-Net OT detection
  50. GRB 250128B: Swift-XRT refined Analysis
  51. GRB 250128B: Fermi GBM Observation
  52. GRB 250128B: GOTO optical upper limit
  53. Swift GRB 250128B: Global MASTER-Net observations report
  54. EP250125a: Upper limits from Swift/BAT-GUANO
  55. GRB 250128B: LCO optical observations
  56. GRB 250128B: Swift detection of a short burst
  57. GRB 250127A: Swift-XRT observations
  58. GRB 250127A: EP-FXT afterglow detection
  59. GRB 250117A: Fermi GBM Observation
  60. GRB 250127A: SVOM/VT upper limit
  61. IPN triangulation of GRB 250119C
  62. GRB 250127A: Swift ToO observations
  63. GRB 250118A: Fermi GBM Observation
  64. EP250125a: REM optical counterpart detection
  65. GRB 250119C: Fermi GBM Observation
  66. EP250125a: Swift/XRT detection of a fading counterpart
  67. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  68. IPN triangulation of GRB 250118B
  69. Konus-Wind detection of GRB 250119B
  70. IPN triangulation of GRB 250119B
  71. Improved IPN triangulation of GRB 250107C
  72. GRB 250114A: Swift-BAT refined analysis
  73. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  74. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  75. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  76. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  77. Konus-Wind detection of GRB 250117A
  78. IPN triangulation of GRB 250117A (short)
  79. GRB 250117A: SVOM/GRM observation of a short burst
  80. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  81. Swift Trigger 1282245 is not a GRB
  82. GRB 250114B: Swift-XRT afterglow detection
  83. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  84. IPN triangulation of GRB 250113A
  85. GRB 250114B: Swift-XRT observations
  86. GRB 250114A: LCO optical counterpart detection.
  87. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  88. GRB 250114A: Swift-XRT refined Analysis
  89. GRB 250114A: LCOGT optical afterglow i-band detection
  90. GRB 250114B: Swift ToO observations
  91. EP250111a: SAO RAS optical upper limit
  92. GRB 250114A: Enhanced Swift-XRT position
  93. GRB 250114A: REM detection of the optical and NIR counterpart
  94. Swift GRB250114A: Global MASTER-Net OT detection
  95. GRB 250114A: LCO optical observations
  96. GRB 250114A: TRT optical observations
  97. Swift GRB 250114A: Global MASTER-Net observations report
  98. GRB 250114A: Swift detection of a burst with an optical counterpart
  99. GRB 250107A: VZLUSAT-2 detection
  100. GRB 250109A / EP250109a: GRBAlpha detection

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