Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

28209 results found.

  1. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  2. Konus-Wind detection of GRB 260209B
  3. GRB 260208A: Swift UVOT detection
  4. Konus-Wind detection of GRB 260127B
  5. GRB 260208A: LCO detection of the optical counterpart
  6. EP260209a: Einstein Probe detection of a fast X-ray transient
  7. IPN triangulation of GRB 260207B (short/hard with EE)
  8. GRB 260210C: Fermi GBM Final Real-time Localization
  9. GRB 260210A: Glowbug gamma-ray detection
  10. GRB 260210B: Fermi GBM Final Real-time Localization
  11. GRB 260210A: AstroSat CZTI detection
  12. GRB 260208C: AstroSat CZTI detection
  13. GRB 260208B: refined analysis of the EP-FXT observation
  14. EP260210a: Einstein Probe detection of an X-ray transient
  15. GRB 260207B: AstroSat CZTI detection
  16. GRB 260204A: Swift-XRT afterglow detection
  17. GRB 260208B: AstroSat CZTI detection of a bright long burst
  18. GRB 260208A: Glowbug gamma-ray detection
  19. GRB 260208A: NuSTAR detection of prompt emission
  20. GRB 260208A: Fermi GBM Observation
  21. GRB 260208B: Swift-XRT observations
  22. GRB 260204A: Swift/UVOT Upper Limits
  23. GRB 260208A: 1.3m DFOT optical detection
  24. GRB 260208B: EP-FXT observation
  25. GRB 260208A: NOT spectroscopic redshift z = 2.36
  26. GRB 260208A: Liverpool Telescope optical detection
  27. GRB 260208B: SVOM/VT optical candidate
  28. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  29. GRB 260209A: Fermi GBM Final Real-time Localization
  30. GRB 260208A: SVOM/VT optical observation
  31. GRB 260208D: Fermi GBM Final Real-time Localization
  32. GRB 260208A: Swift-XRT observations
  33. GRB 260208B: Swift ToO observations
  34. GRB 260208B: Fermi GBM Detection
  35. GRB 260208B: Fermi-LAT detection
  36. GRB 260208C: Fermi GBM Final Real-time Localization
  37. GRB 260208A: Fermi-LAT detection
  38. GRB 260208A: Swift ToO observations
  39. GRB 260208A: Fermi GBM Classification Correction
  40. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  41. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  42. GRB 260208B: Fermi GBM Final Real-time Localization
  43. GRB 260208A: Fermi GBM Final Real-time Localization
  44. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  45. GRB 260207A : MASTER optical counterpart discovery
  46. GRB 260206A: Swift-XRT observations
  47. GRB 260207B: Fermi GBM Final Real-time Localization
  48. GRB 260207A: Fermi GBM Final Localization
  49. EP260131a: VLA detection
  50. GRB 260206A: Tiled Swift observations
  51. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  52. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  53. GRB 260204A: Swift-XRT observations
  54. GRB 260204A: LCO optical afterglow detection
  55. GRB 260204A: SVOM/VT optical candidate
  56. Fermi GBM Sub-Threshold Detection of GRB 260204A
  57. GRB 260204B: Fermi GBM Final Real-time Localization
  58. GRB 260204A: SVOM detection of a burst
  59. GRB 260121A: 239Alferov CubeSat detection
  60. Konus-Wind detection of GRB 260121A
  61. GRB 260131A/B: OHP/T193 optical observations
  62. GRB 260131A: KAIT optical observations
  63. GRB 251230A: MeerLICHT afterglow detection
  64. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  65. GRID detection of GRB 260131A/B
  66. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  67. GRB 260130A: Insight-HXMT/HE detection
  68. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  69. GRB 260131A/B: EP/FXT X-ray afterglow detection
  70. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  71. GRB 260127B: Insight-HXMT/HE detection
  72. GRB 260131A: NOT spectroscopic redshift z = 1.434
  73. Konus-Wind detection of GRB 260128A / EP260128a
  74. GRB 260131A: Insight-HXMT/HE detection
  75. Konus-Wind detection of GRB 260131A/B
  76. EP260131a: Xinglong optical upper limit
  77. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  78. EP260131a: COLIBRÍ observations of slow optical fading
  79. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  80. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  81. GRB 260131B: MAXI/GSC detection
  82. GRB 260131A: Fermi GBM Final Real-time Localization
  83. EP260131a: Las Cumbres detection of an optical counterpart
  84. GRB 260127B: AstroSat CZTI detection
  85. GRB 260130A: Fermi GBM Detection
  86. EP260131a: Einstein Probe detection of an X-ray transient
  87. GRB 260127B: Fermi GBM Detection
  88. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  89. GRB 260130A: Fermi GBM Final Real-time Localization
  90. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  91. GRB 260129B: Fermi GBM Final Localization
  92. GRB 260128B: SVOM detection of a burst through offline search
  93. GRB 260129A: Fermi GBM Final Localization
  94. IPN triangulation of GRB 260127B (short)
  95. GRB 260127B: Swift-XRT observations
  96. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  97. EP260128a: NOT optical counterpart candidate
  98. EP260128a: Liverpool Telescope optical observations and possible counterpart
  99. EP260126a: SVOM/VT optical upperlimit
  100. EP260128a: Einstein Probe detection of an X-ray transient

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