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"

36194 results found.

  1. GRB 260208B: COLIBRÍ optical observations
  2. GRB 260208A: Mondy optical observations (duplicate submission)
  3. GRB 260208A: Mondy optical observations
  4. GRB 260208A: 1.3m DFOT optical detection
  5. GRB 260208A: COLIBRÍ optical observations
  6. GRB 260208B: EP-FXT observation
  7. GRB 260208A: NOT spectroscopic redshift z = 2.36
  8. GRB 260208A: Liverpool Telescope optical detection
  9. Fermi GRB 260208C: Global MASTER-Net observations report
  10. GRB 260208B: SVOM/VT optical candidate
  11. GRB 260208A: GECAM-B observation of a bright burst
  12. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  13. GRB 260209A: Fermi GBM Final Real-time Localization
  14. GRB 260208A: SVOM/VT optical observation
  15. Fermi GRB 260208D: Global MASTER-Net observations report
  16. GRB 260208D: Fermi GBM Final Real-time Localization
  17. GRB 260208A: Swift-XRT observations
  18. GRB 260208B: Swift ToO observations
  19. GRB 260208B: SVOM/GRM observation of a bright burst
  20. GRB 260208B: Fermi GBM Detection
  21. LAT GRB 260208B: Global MASTER-Net observations report
  22. GRB 260208B: Fermi-LAT detection
  23. GRB 260208C: Fermi GBM Final Real-time Localization
  24. GRB 260208A: Fermi-LAT detection
  25. GRB 260207B: GECAM-B observation
  26. GRB 260208A: Swift ToO observations
  27. GRB 260208A: Fermi GBM Classification Correction
  28. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  29. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  30. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  31. GRB 260208B: Fermi GBM Final Real-time Localization
  32. Fermi GRB 260208A: Global MASTER-Net observations report
  33. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  34. GRB 260208A: Fermi GBM Final Real-time Localization
  35. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  36. GRB 260207A : MASTER optical counterpart discovery
  37. GRB 260131A/B: Mondy and Terskol optical observations
  38. Fermi GRB 260207B: Global MASTER-Net observations report
  39. GRB 260206A: Swift-XRT observations
  40. GRB 260207B: Fermi GBM Final Real-time Localization
  41. GRB 260207A: Fermi GBM Final Localization
  42. EP260131a: VLA detection
  43. GRB 260206A: Tiled Swift observations
  44. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  45. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  46. GRB 260204A: Swift-XRT observations
  47. GRB 260204A: LCO optical afterglow detection
  48. GRB 260204A: SVOM/VT optical candidate
  49. GRB 260204A : MASTER Global robotic net optical observations
  50. Fermi GBM Sub-Threshold Detection of GRB 260204A
  51. GRB 260204A: GOTO optical upper limit
  52. GRB 260204A: LCO optical upper limits
  53. GRB 260204B: Fermi GBM Final Real-time Localization
  54. GRB 260204A: SVOM detection of a burst
  55. GRB 260121A: 239Alferov CubeSat detection
  56. Konus-Wind detection of GRB 260121A
  57. GRB 260131A/B: OHP/T193 optical observations
  58. GRB 260131A: KAIT optical observations
  59. GRB 251230A: MeerLICHT afterglow detection
  60. GRB 260131A: FTW optical and NIR observations
  61. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  62. GRID detection of GRB 260131A/B
  63. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  64. GRB 260130A: Insight-HXMT/HE detection
  65. GRB 260130A: GECAM-B observation of a short burst
  66. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  67. GRB 260131A/B: EP/FXT X-ray afterglow detection
  68. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  69. GRB 260127B: Insight-HXMT/HE detection
  70. GRB 260127B: GECAM-B observation of a short burst
  71. GRB 260127A: GECAM-B observation
  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. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  77. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  78. GRB 260131A/B: Fermi GBM Observation
  79. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  80. GRB 260131B: MAXI/GSC detection
  81. GRB 260131A: Fermi GBM Final Real-time Localization
  82. GRB 260127B: AstroSat CZTI detection
  83. GRB 260130A: Fermi GBM Detection
  84. GRB 260127B: Fermi GBM Detection
  85. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  86. Fermi GRB 260130A: Global MASTER-Net observations report
  87. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  88. GRB 260130A: Fermi GBM Final Real-time Localization
  89. Fermi GRB 260129A: Global MASTER-Net observations report
  90. GRB 260128B: LCO optical upper limits
  91. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  92. IPN triangulation of GRB 260121A
  93. GRB 260127A: Swift-BAT refined analysis
  94. GRB 260129B: Fermi GBM Final Localization
  95. GRB 260128B: SVOM detection of a burst through offline search
  96. GRB 260129A: Fermi GBM Final Localization
  97. IPN triangulation of GRB 260127B (short)
  98. GRB 260127B: Swift-XRT observations
  99. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  100. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection

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