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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"

19596 results found.

  1. GRB 250129A: Enhanced Swift-XRT position
  2. GRB 250128B: NOT optical upper limit
  3. GRB 250129A: REM optical/NIR afterglow detection
  4. GRB 250129A: Early afterglow detection by LCO.
  5. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  6. GRB 250129A: LCO optical observations
  7. GRB 250129A: GOTO optical observations show brightening afterglow
  8. Swift GRB 250129A: Global MASTER-Net observations report
  9. GRB 250128B: Enhanced Swift-XRT position
  10. GRB 250129A: Swift detection of a burst with an optical counterpart
  11. Swift GRB 250129A: Global MASTER-Net OT detection
  12. GRB 250128B: Swift-XRT refined Analysis
  13. GRB 250128B: Fermi GBM Observation
  14. GRB 250128B: GOTO optical upper limit
  15. Swift GRB 250128B: Global MASTER-Net observations report
  16. EP250125a: Upper limits from Swift/BAT-GUANO
  17. GRB 250128B: LCO optical observations
  18. GRB 250128B: Swift detection of a short burst
  19. GRB 250127A: Swift-XRT observations
  20. GRB 250127A: EP-FXT afterglow detection
  21. GRB 250117A: Fermi GBM Observation
  22. GRB 250127A: SVOM/VT upper limit
  23. IPN triangulation of GRB 250119C
  24. GRB 250127A: Swift ToO observations
  25. GRB 250118A: Fermi GBM Observation
  26. EP250125a: REM optical counterpart detection
  27. GRB 250119C: Fermi GBM Observation
  28. EP250125a: Swift/XRT detection of a fading counterpart
  29. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  30. IPN triangulation of GRB 250118B
  31. Konus-Wind detection of GRB 250119B
  32. IPN triangulation of GRB 250119B
  33. Improved IPN triangulation of GRB 250107C
  34. GRB 250114A: Swift-BAT refined analysis
  35. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  36. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  37. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  38. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  39. Konus-Wind detection of GRB 250117A
  40. IPN triangulation of GRB 250117A (short)
  41. GRB 250117A: SVOM/GRM observation of a short burst
  42. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  43. Swift Trigger 1282245 is not a GRB
  44. GRB 250114B: Swift-XRT afterglow detection
  45. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  46. IPN triangulation of GRB 250113A
  47. GRB 250114B: Swift-XRT observations
  48. GRB 250114A: LCO optical counterpart detection.
  49. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  50. GRB 250114A: Swift-XRT refined Analysis
  51. GRB 250114A: LCOGT optical afterglow i-band detection
  52. GRB 250114B: Swift ToO observations
  53. EP250111a: SAO RAS optical upper limit
  54. GRB 250114A: Enhanced Swift-XRT position
  55. GRB 250114A: REM detection of the optical and NIR counterpart
  56. Swift GRB250114A: Global MASTER-Net OT detection
  57. GRB 250114A: LCO optical observations
  58. GRB 250114A: TRT optical observations
  59. Swift GRB 250114A: Global MASTER-Net observations report
  60. GRB 250114A: Swift detection of a burst with an optical counterpart
  61. GRB 250107A: VZLUSAT-2 detection
  62. GRB 250109A / EP250109a: GRBAlpha detection
  63. GRB 250106A: Swift-XRT afterglow detection
  64. GRB 250109A / EP250109a: Mephisto optical upper limits
  65. EP250111a: Swift/XRT detection and fading
  66. EP250108a / AT 2025kg: Swift UVOT detections
  67. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  68. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  69. GRB 250108A: Swift/XRT afterglow fading
  70. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  71. EP250109a: Swift/UVOT non-detection
  72. IPN triangulation of GRB 250107D (short/hard)
  73. IPN triangulation of GRB 250107C
  74. GRB 250108B: Swift-BAT refined analysis
  75. GRB 250108B: 1.3m DFOT upper limit
  76. GRB 250108B: REM optical/NIR upper limits
  77. EP250109a: GOTO optical upper limits
  78. EP250109a: Swift/XRT non-detection
  79. GRB 250108A: Swift/UVOT Upper Limits
  80. GRB 250108A: NOT optical upper limit
  81. GRB 250108B: Swift-XRT refined Analysis
  82. Swift GRB 250108B: Global MASTER-Net observations report
  83. GRB 250108A: Swift-XRT afterglow detection
  84. GRB 250108B: Swift/UVOT Upper Limits
  85. GRB 250103A: Swift-XRT afterglow detection
  86. GRB 250108B: Enhanced Swift-XRT position
  87. GRB 250108B: Swift detection of a burst
  88. GRB 250108A: Swift ToO observations
  89. GRB 250107A: Fermi GBM Observation
  90. GRB 241228B: Fermi-LAT detection
  91. GRB 250107A: Swift ToO observations
  92. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  93. GRB 250106A: NOT optical observations
  94. GRB 250103B: REM optical/NIR upper limits
  95. GRB 250101A: REM optical/NIR counterpart detection
  96. GRB 250106A: Swift-XRT observations
  97. GRB 250106A: Swift ToO observations
  98. GRB 241229A: SVOM/VT optical upperlimit
  99. GRB 250103B: Swift-XRT refined Analysis
  100. GRB 250103B: LCO/1m optical afterglow candidate detection

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