Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

11099 results found.

  1. GRB 260326A: Fermi GBM Final Real-time Localization
  2. Fermi Gamma-ray Burst Monitor trigger 796145512/260325647 is not a GRB
  3. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  4. IPN triangulation of GRB 260316B
  5. Fermi Gamma-ray Burst Monitor trigger 796060650/260324665 is not a GRB
  6. GRB 260310A: LBT optical observations
  7. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  8. Fermi GRB 260323A: Global MASTER-Net observations report
  9. GRB 260323A: Fermi GBM Final Real-time Localization
  10. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  11. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  12. GRB 260322A: Fermi GBM Final Localization
  13. Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
  14. GRB 260310A: continued optical observation at Mondy
  15. Fermi GBM Sub-Threshold Detection of GRB 260321A
  16. GRB 260318A: Glowbug gamma-ray detection
  17. GRB 260310A / AT 2026fgk: KAIT optical observations
  18. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  19. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  20. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  21. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  22. GRB 260310A/AT2026fgk: LBT near-infrared observations
  23. GRB 260318A: SVOM/GRM observation
  24. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  25. GRB 260318A: GECAM-B observation
  26. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  27. Fermi GRB 260318A: Global MASTER-Net observations report
  28. GRB 260318A: Fermi GBM Final Real-time Localization
  29. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  30. GRB 260310A / AT 2026fgk: radio detection with the VLA
  31. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  32. GRB 260310A / AT2026fgk: LCO optical observations
  33. GRB 260317A: Fermi GBM Final Localization
  34. GRB 260316B: GECAM-B observation
  35. GRB 260316B: SVOM/GRM observation
  36. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  37. EP260316a: COLIBRÍ faint optical counterpart candidate
  38. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  39. GRB 260316B: AstroSat CZTI detection
  40. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  41. GRB 260316B: Fermi GBM Final Real-time Localization
  42. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  43. GRB 260314A: Glowbug gamma-ray detection
  44. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  45. GRB 260310A / AT 2026fgk: iTelescope optical observations
  46. GRID detection of GRB 260312B
  47. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  48. Fermi trigger No 795185313: Global MASTER-Net observations report
  49. GRB 260314A: GECAM-B observation of a burst
  50. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  51. GRB 260310A / AT2026fgk: SAO RAS optical observations
  52. GRB 260310A/AT2026fgk: radio detection at 15GHz
  53. GRB 260310A / AT2026fgk: TNG NIR detection
  54. GRB 260310A / AT2026fgk: OASDG optical observations
  55. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  56. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  57. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  58. Fermi GRB 260314A: Global MASTER-Net observations report
  59. Fermi GRB 260313A: Global MASTER-Net observations report
  60. GRB 260314A: Fermi GBM Final Real-time Localization
  61. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  62. GRB 260313A: A Correction to the Fermi GBM Final Localization
  63. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  64. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  65. GRB 260310B: Insight-HXMT/HE detection
  66. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  67. GRB 260312B: AstroSat CZTI detection
  68. GRB 260313A: Fermi GBM Final Real-time Localization
  69. GRB 260308A: Insight-HXMT/HE detection
  70. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  71. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  72. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  73. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  74. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  75. GRB260310A / AT2026fgk: P200 Spectroscopy
  76. GRB 260312B: Glowbug gamma-ray detection
  77. GRB 260310A: Fermi GBM Observation
  78. GRB 260310A: potential optical counterpart
  79. Fermi GRB 260312B: Global MASTER-Net observations report
  80. Fermi GRB 260311B: Global MASTER-Net observations report
  81. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  82. GRB 260312B: Fermi GBM Final Real-time Localization
  83. GRB 260310B: GECAM-B observation of a burst
  84. GRB 260311B: Fermi GBM Final Real-time Localization
  85. GRB 260131A/B: radio detection with the VLA
  86. GRB260307A: GECAM-B observation of a burst
  87. GRB 260308A: SVOM/GRM observation of a short GRB
  88. GRB 260310A: AstroSat CZTI detection of a long burst
  89. GRB 260311A: Fermi GBM Final Real-time Localization
  90. Fermi GRB 260310B: Global MASTER-Net observations report
  91. GRB 260310B: Fermi GBM Final Real-time Localization
  92. Fermi GRB 260310A: Global MASTER-Net observations report
  93. GRB 260307B: SVOM/ECLAIRs refined analysis
  94. GRB 260208A: radio detection with the VLA
  95. GRB 260310A: Fermi GBM Final Real-time Localization
  96. GRB 260307A: Glowbug gamma-ray detection
  97. GRB 260308A: Fermi GBM Final Real-time Localization
  98. Fermi GBM Sub-Threshold Detection of GRB 260307B
  99. Fermi GRB 260307A: Global MASTER-Net observations report
  100. GRB 260307A: Fermi GBM Final Localization

Advanced

Download all Circulars as a .tar.gz archive:
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