Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

37755 results found.

  1. Fermi GRB 260129A: Global MASTER-Net observations report
  2. GRB 260128B: LCO optical upper limits
  3. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  4. IPN triangulation of GRB 260121A
  5. GRB 260127A: Swift-BAT refined analysis
  6. GRB 260129B: Fermi GBM Final Localization
  7. GRB 260128B: SVOM detection of a burst through offline search
  8. GRB 260129A: Fermi GBM Final Localization
  9. IPN triangulation of GRB 260127B (short)
  10. GRB 260127B: Swift-XRT observations
  11. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  12. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  13. Fermi GRB 260127A: Global MASTER-Net observations report
  14. GRB 260127A: Fermi GBM Observation
  15. GRB 260127A: COLIBRÍ optical observations
  16. GRB 260127A: NOT optical observations
  17. GRB 260127B: Swift ToO observations
  18. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  19. GRB 260127A: Swift-XRT refined Analysis
  20. GRB 260127B: GOTO candidate optical counterpart
  21. GRB 260127A: SVOM/C-GFT optical observations
  22. GRB 260127A: Enhanced Swift-XRT position
  23. Fermi GRB 260127B: Global MASTER-Net observations report
  24. GRB 260127B: Fermi GBM Final Real-time Localization
  25. GRB 260127A: Prompt enhanced Swift-XRT position
  26. Swift GRB 260127A: Global MASTER-Net observations report
  27. GRB 260127A: LCO optical afterglow discovery
  28. GRB 260127A: Swift detection of a burst
  29. GRB 260127A: Fermi GBM Final Real-time Localization
  30. GRB 260125A: Swift-XRT observations
  31. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  32. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  33. Konus-Wind detection of GRB 260120B
  34. GRB 251222A: SVOM/ECLAIRs refined analysis
  35. GRB 260125A: Swift ToO observations
  36. GRB 260125A: GOTO candidate optical counterpart
  37. Fermi GRB 260125B: Global MASTER-Net observations report
  38. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  39. GRB 260125B: Fermi GBM Final Real-time Localization
  40. GRB 260125A: Fermi GBM Final Real-time Localization
  41. GRB 260114A: SVOM/VT optical upper limits
  42. GRB 260120A: AstroSat CZTI detection
  43. GRB 260122B: Swift-BAT refined analysis
  44. GRB 260120B: SVOM/GRM observation
  45. GRB 260120A: GECAM-B observation
  46. GRB 260120B: AstroSat CZTI detection
  47. GRB 260114A: Insight-HXMT/HE detection
  48. GRB 260122B: Swift detection of a burst
  49. EP260119a: Assy AZT-20 optical observations
  50. EP260119a: Mondy and SAO RAS optical upper limits
  51. GRB 260122A: Fermi GBM Final Real-time Localization
  52. Fermi GRB 260120C: Global MASTER-Net observations report
  53. GRB 260120B: Swift-BAT refined analysis
  54. GRB 260120B: Swift-XRT refined Analysis
  55. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  56. GRB 260120B: Fermi GBM Observation
  57. GRB 260120B: Swift/UVOT Detection
  58. GRB 260120B: COLIBRÍ optical upper limits
  59. GRB 260120B: Enhanced Swift-XRT position
  60. GRB 260120B: SVOM/C-GFT optical counterpart detection
  61. GRB 260120C: Fermi GBM Final Real-time Localization
  62. GRB 260101A: 239Alferov CubeSat detection
  63. GRB 260120B: Swift detection of a burst
  64. GRB 260120B: Fermi GBM Final Real-time Localization
  65. EP260119A: Mondy I-Band Observations
  66. Fermi trigger No 790601190: Global MASTER-Net observations report
  67. Fermi trigger No 790570272: Global MASTER-Net observations report
  68. GRB 260114A: Swift/UVOT Upper Limits
  69. GRB 251202A: further radio observations with the VLA
  70. EP260119a: KAIT optical observations
  71. GRB 260120A: Fermi GBM Final Real-time Localization
  72. EP260119a: SAO RAS optical observations
  73. GRB 251208D: SVOM/ECLAIRs refined analysis
  74. GRB 251208D: SVOM/ECLAIRs refined analysis
  75. GRB 260117A: Swift-XRT afterglow detection
  76. GRB 260115A: AstroSat CZTI detection
  77. GRB 260117A: ZTSh optical upper limit
  78. GRB 260110A: SVOM detection of a burst through offline search
  79. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  80. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  81. GRB 260117A: SVOM/VT optical candidate
  82. GRB 260117A: SVOM/C-GFT upper limit
  83. GRB 260117A: Swift-XRT observations
  84. GRB 260117A: Swift ToO observations
  85. GRB 260117A: SVOM detection of a long faint burst
  86. GRB 260115A: GECAM-B observation
  87. GRB 260114A: VLT/MUSE spectroscopic observations
  88. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  89. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  90. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  92. Fermi GRB 260115A: Global MASTER-Net observations report
  93. GRB 260115A: Fermi GBM Final Real-time Localization
  94. GRB260114A: STEP/T80S optical limits
  95. GRB 251222A: radio detection with the VLA
  96. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  97. Konus-Wind detection of GRB 260114A
  98. GRB 260114A: Swift-XRT refined Analysis
  99. GRB 260114A: 6 GHz VLA observations
  100. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov