Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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"

18632 results found.

  1. GRB 250207A: Enhanced Swift-XRT position
  2. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  3. GRB 250207A: REM IR afterglow detection
  4. GRB 250207A: FRAM-Auger optical detection
  5. GRB 250207B: Tiled Swift observations
  6. GRB 250207A: REM optical afterglow detection
  7. GRB 250207A: Swift/UVOT Detection
  8. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  9. GRB 250207A: Swift detection of a burst with optical counterpart
  10. GRB 250205A: Fermi GBM Observation
  11. GRB 250205A: Swift/UVOT Upper Limits
  12. GRB 250205A: Swift/XRT detection
  13. IPN triangulation of GRB 250201A
  14. GRB 250129A: Swift-BAT refined analysis
  15. IPN triangulation of GRB 250204B (short/hard)
  16. IPN triangulation of GRB 250202B
  17. GRB 250129A: LCO late afterglow detection
  18. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  19. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  20. GRB 250129A: SVOM/C-GFT optical observations
  21. Swift GRB250129A: MASTER 4 days observations report
  22. Konus-Wind detection of GRB 250129A
  23. GRB 250129A: 1.3m DFOT Optical observations
  24. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  25. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  26. GRB 250129A: COLIBRÍ Optical Observations
  27. GRB 250129A: TNG NIR afterglow detection
  28. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  29. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  30. GRB 250128B: VLA radio upper limit
  31. Ep250125A: 1.3m DFOT optical upper limit
  32. GRB 250129A: Skynet optical observations
  33. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  34. GRB 250129A: Swift-XRT refined Analysis
  35. GRB 250128B: TNG optical upper limit
  36. GRB 250129A: Swift/UVOT Detection
  37. GRB 250127A: CrAO and Terskol optical upper limits
  38. GRB 250129A: Enhanced Swift-XRT position
  39. GRB 250128B: NOT optical upper limit
  40. GRB 250129A: REM optical/NIR afterglow detection
  41. GRB 250129A: Early afterglow detection by LCO.
  42. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  43. GRB 250129A: LCO optical observations
  44. GRB 250129A: GOTO optical observations show brightening afterglow
  45. Swift GRB 250129A: Global MASTER-Net observations report
  46. GRB 250128B: Enhanced Swift-XRT position
  47. GRB 250129A: Swift detection of a burst with an optical counterpart
  48. Swift GRB 250129A: Global MASTER-Net OT detection
  49. GRB 250128B: Swift-XRT refined Analysis
  50. GRB 250128B: Fermi GBM Observation
  51. GRB 250128B: GOTO optical upper limit
  52. Swift GRB 250128B: Global MASTER-Net observations report
  53. EP250125a: Upper limits from Swift/BAT-GUANO
  54. GRB 250128B: LCO optical observations
  55. GRB 250128B: Swift detection of a short burst
  56. GRB 250127A: Swift-XRT observations
  57. GRB 250127A: EP-FXT afterglow detection
  58. GRB 250117A: Fermi GBM Observation
  59. GRB 250127A: SVOM/VT upper limit
  60. IPN triangulation of GRB 250119C
  61. GRB 250127A: Swift ToO observations
  62. GRB 250118A: Fermi GBM Observation
  63. EP250125a: REM optical counterpart detection
  64. GRB 250119C: Fermi GBM Observation
  65. EP250125a: Swift/XRT detection of a fading counterpart
  66. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  67. IPN triangulation of GRB 250118B
  68. Konus-Wind detection of GRB 250119B
  69. IPN triangulation of GRB 250119B
  70. Improved IPN triangulation of GRB 250107C
  71. GRB 250114A: Swift-BAT refined analysis
  72. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  73. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  74. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  75. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  76. Konus-Wind detection of GRB 250117A
  77. IPN triangulation of GRB 250117A (short)
  78. GRB 250117A: SVOM/GRM observation of a short burst
  79. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  80. Swift Trigger 1282245 is not a GRB
  81. GRB 250114B: Swift-XRT afterglow detection
  82. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  83. IPN triangulation of GRB 250113A
  84. GRB 250114B: Swift-XRT observations
  85. GRB 250114A: LCO optical counterpart detection.
  86. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  87. GRB 250114A: Swift-XRT refined Analysis
  88. GRB 250114A: LCOGT optical afterglow i-band detection
  89. GRB 250114B: Swift ToO observations
  90. EP250111a: SAO RAS optical upper limit
  91. GRB 250114A: Enhanced Swift-XRT position
  92. GRB 250114A: REM detection of the optical and NIR counterpart
  93. Swift GRB250114A: Global MASTER-Net OT detection
  94. GRB 250114A: LCO optical observations
  95. GRB 250114A: TRT optical observations
  96. Swift GRB 250114A: Global MASTER-Net observations report
  97. GRB 250114A: Swift detection of a burst with an optical counterpart
  98. GRB 250107A: VZLUSAT-2 detection
  99. GRB 250109A / EP250109a: GRBAlpha detection
  100. GRB 250106A: Swift-XRT afterglow detection

Advanced

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