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"

11627 results found.

  1. Fermi trigger No 792537871: Global MASTER-Net observations report
  2. GRB 260208A: Swift UVOT detection
  3. Konus-Wind detection of GRB 260127B
  4. Fermi GRB 260210C: Global MASTER-Net observations report
  5. GRB 260208A: LCO detection of the optical counterpart
  6. IPN triangulation of GRB 260207B (short/hard with EE)
  7. GRB 260210C: Fermi GBM Final Real-time Localization
  8. GRB 260210B: Fermi GBM Final Real-time Localization
  9. GRB 260208C: AstroSat CZTI detection
  10. GRB 260208B: refined analysis of the EP-FXT observation
  11. GRB 260207B: AstroSat CZTI detection
  12. GRB 260208C: SVOM/GRM observation
  13. GRB 260208B: AstroSat CZTI detection of a bright long burst
  14. GRB260208A: Liverpool Telescope optical follow-up observations
  15. GRB 260208A: Glowbug gamma-ray detection
  16. GRB 260208A: NuSTAR detection of prompt emission
  17. GRB 260208A: Fermi GBM Observation
  18. Fermi GRB 260209A: Global MASTER-Net observations report
  19. GRB 260208B: Swift-XRT observations
  20. GRB 260131A/B: continued Mondy optical observations
  21. GRB 260208B: COLIBRÍ optical observations
  22. GRB 260208A: Mondy optical observations
  23. GRB 260208A: 1.3m DFOT optical detection
  24. GRB 260208A: COLIBRÍ optical observations
  25. GRB 260208B: EP-FXT observation
  26. GRB 260208A: NOT spectroscopic redshift z = 2.36
  27. GRB 260208A: Liverpool Telescope optical detection
  28. Fermi GRB 260208C: Global MASTER-Net observations report
  29. GRB 260208B: SVOM/VT optical candidate
  30. GRB 260208A: GECAM-B observation of a bright burst
  31. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  32. GRB 260209A: Fermi GBM Final Real-time Localization
  33. GRB 260208A: SVOM/VT optical observation
  34. Fermi GRB 260208D: Global MASTER-Net observations report
  35. GRB 260208D: Fermi GBM Final Real-time Localization
  36. GRB 260208A: Swift-XRT observations
  37. GRB 260208B: Swift ToO observations
  38. GRB 260208B: SVOM/GRM observation of a bright burst
  39. GRB 260208B: Fermi GBM Detection
  40. GRB 260208B: Fermi-LAT detection
  41. GRB 260208C: Fermi GBM Final Real-time Localization
  42. GRB 260208A: Fermi-LAT detection
  43. GRB 260207B: GECAM-B observation
  44. GRB 260208A: Swift ToO observations
  45. GRB 260208A: Fermi GBM Classification Correction
  46. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  47. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  48. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  49. GRB 260208B: Fermi GBM Final Real-time Localization
  50. Fermi GRB 260208A: Global MASTER-Net observations report
  51. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  52. GRB 260208A: Fermi GBM Final Real-time Localization
  53. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  54. GRB 260207A : MASTER optical counterpart discovery
  55. GRB 260131A/B: Mondy and Terskol optical observations
  56. Fermi GRB 260207B: Global MASTER-Net observations report
  57. GRB 260207B: Fermi GBM Final Real-time Localization
  58. GRB 260207A: Fermi GBM Final Localization
  59. Fermi trigger No 792135758: Global MASTER-Net observations report
  60. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  61. GRB 260204A : MASTER Global robotic net optical observations
  62. Fermi GBM Sub-Threshold Detection of GRB 260204A
  63. GRB 260204B: Fermi GBM Final Real-time Localization
  64. GRB 260131A/B: OHP/T193 optical observations
  65. GRB 260131A: KAIT optical observations
  66. GRB 260131A: FTW optical and NIR observations
  67. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  68. GRID detection of GRB 260131A/B
  69. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  70. GRB 260130A: Insight-HXMT/HE detection
  71. GRB 260130A: GECAM-B observation of a short burst
  72. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  73. GRB 260131A/B: EP/FXT X-ray afterglow detection
  74. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  75. GRB 260127B: Insight-HXMT/HE detection
  76. GRB 260127B: GECAM-B observation of a short burst
  77. GRB 260127A: GECAM-B observation
  78. GRB 260131A: NOT spectroscopic redshift z = 1.434
  79. Konus-Wind detection of GRB 260128A / EP260128a
  80. GRB 260131A: Insight-HXMT/HE detection
  81. Konus-Wind detection of GRB 260131A/B
  82. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  83. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  84. GRB 260131A/B: Fermi GBM Observation
  85. GRB 260131A: Fermi GBM Final Real-time Localization
  86. GRB 260127B: AstroSat CZTI detection
  87. GRB 260130A: Fermi GBM Detection
  88. GRB 260127B: Fermi GBM Detection
  89. Fermi GRB 260130A: Global MASTER-Net observations report
  90. GRB 260130A: Fermi GBM Final Real-time Localization
  91. Fermi GRB 260129A: Global MASTER-Net observations report
  92. IPN triangulation of GRB 260121A
  93. GRB 260129B: Fermi GBM Final Localization
  94. GRB 260129A: Fermi GBM Final Localization
  95. IPN triangulation of GRB 260127B (short)
  96. GRB 260127B: Swift-XRT observations
  97. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  98. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  99. Fermi GRB 260127A: Global MASTER-Net observations report
  100. GRB 260127A: Fermi GBM Observation

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