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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"

19588 results found.

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

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