Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

19603 results found.

  1. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  2. GRB 250128B: VLA radio upper limit
  3. Ep250125A: 1.3m DFOT optical upper limit
  4. GRB 250129A: Skynet optical observations
  5. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  6. GRB 250129A: Swift-XRT refined Analysis
  7. GRB 250128B: TNG optical upper limit
  8. GRB 250129A: Swift/UVOT Detection
  9. GRB 250127A: CrAO and Terskol optical upper limits
  10. GRB 250129A: Enhanced Swift-XRT position
  11. GRB 250128B: NOT optical upper limit
  12. GRB 250129A: REM optical/NIR afterglow detection
  13. GRB 250129A: Early afterglow detection by LCO.
  14. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  15. GRB 250129A: LCO optical observations
  16. GRB 250129A: GOTO optical observations show brightening afterglow
  17. Swift GRB 250129A: Global MASTER-Net observations report
  18. GRB 250128B: Enhanced Swift-XRT position
  19. GRB 250129A: Swift detection of a burst with an optical counterpart
  20. Swift GRB 250129A: Global MASTER-Net OT detection
  21. GRB 250128B: Swift-XRT refined Analysis
  22. GRB 250128B: Fermi GBM Observation
  23. GRB 250128B: GOTO optical upper limit
  24. Swift GRB 250128B: Global MASTER-Net observations report
  25. EP250125a: Upper limits from Swift/BAT-GUANO
  26. GRB 250128B: LCO optical observations
  27. GRB 250128B: Swift detection of a short burst
  28. GRB 250127A: Swift-XRT observations
  29. GRB 250127A: EP-FXT afterglow detection
  30. GRB 250117A: Fermi GBM Observation
  31. GRB 250127A: SVOM/VT upper limit
  32. IPN triangulation of GRB 250119C
  33. GRB 250127A: Swift ToO observations
  34. GRB 250118A: Fermi GBM Observation
  35. EP250125a: REM optical counterpart detection
  36. GRB 250119C: Fermi GBM Observation
  37. EP250125a: Swift/XRT detection of a fading counterpart
  38. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  39. IPN triangulation of GRB 250118B
  40. Konus-Wind detection of GRB 250119B
  41. IPN triangulation of GRB 250119B
  42. Improved IPN triangulation of GRB 250107C
  43. GRB 250114A: Swift-BAT refined analysis
  44. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  45. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  46. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  47. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  48. Konus-Wind detection of GRB 250117A
  49. IPN triangulation of GRB 250117A (short)
  50. GRB 250117A: SVOM/GRM observation of a short burst
  51. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  52. Swift Trigger 1282245 is not a GRB
  53. GRB 250114B: Swift-XRT afterglow detection
  54. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  55. IPN triangulation of GRB 250113A
  56. GRB 250114B: Swift-XRT observations
  57. GRB 250114A: LCO optical counterpart detection.
  58. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  59. GRB 250114A: Swift-XRT refined Analysis
  60. GRB 250114A: LCOGT optical afterglow i-band detection
  61. GRB 250114B: Swift ToO observations
  62. EP250111a: SAO RAS optical upper limit
  63. GRB 250114A: Enhanced Swift-XRT position
  64. GRB 250114A: REM detection of the optical and NIR counterpart
  65. Swift GRB250114A: Global MASTER-Net OT detection
  66. GRB 250114A: LCO optical observations
  67. GRB 250114A: TRT optical observations
  68. Swift GRB 250114A: Global MASTER-Net observations report
  69. GRB 250114A: Swift detection of a burst with an optical counterpart
  70. GRB 250107A: VZLUSAT-2 detection
  71. GRB 250109A / EP250109a: GRBAlpha detection
  72. GRB 250106A: Swift-XRT afterglow detection
  73. GRB 250109A / EP250109a: Mephisto optical upper limits
  74. EP250111a: Swift/XRT detection and fading
  75. EP250108a / AT 2025kg: Swift UVOT detections
  76. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  77. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  78. GRB 250108A: Swift/XRT afterglow fading
  79. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  80. EP250109a: Swift/UVOT non-detection
  81. IPN triangulation of GRB 250107D (short/hard)
  82. IPN triangulation of GRB 250107C
  83. GRB 250108B: Swift-BAT refined analysis
  84. GRB 250108B: 1.3m DFOT upper limit
  85. GRB 250108B: REM optical/NIR upper limits
  86. EP250109a: GOTO optical upper limits
  87. EP250109a: Swift/XRT non-detection
  88. GRB 250108A: Swift/UVOT Upper Limits
  89. GRB 250108A: NOT optical upper limit
  90. GRB 250108B: Swift-XRT refined Analysis
  91. Swift GRB 250108B: Global MASTER-Net observations report
  92. GRB 250108A: Swift-XRT afterglow detection
  93. GRB 250108B: Swift/UVOT Upper Limits
  94. GRB 250103A: Swift-XRT afterglow detection
  95. GRB 250108B: Enhanced Swift-XRT position
  96. GRB 250108B: Swift detection of a burst
  97. GRB 250108A: Swift ToO observations
  98. GRB 250107A: Fermi GBM Observation
  99. GRB 241228B: Fermi-LAT detection
  100. GRB 250107A: Swift ToO observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov