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"

28196 results found.

  1. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  2. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  3. GRB 260322A: Fermi GBM Final Localization
  4. GRB 260320A: Glowbug gamma-ray detection
  5. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  6. EP260321a: COLIBRÍ further optical observations and brightening
  7. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  8. EP260214b: ATCA 6 GHz detection
  9. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  10. EP260321a: GOTO detection of blue variable source
  11. EP260321a: further Kinder optical observations
  12. GRB 260320A: Insight-HXMT/HE detection
  13. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  14. Fermi GBM Sub-Threshold Detection of GRB 260321A
  15. GRB 260321A: SVOM detection of a burst
  16. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  17. EP260321a: Einstein Probe detection of an X-ray transient
  18. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  19. GRB 260318A: Glowbug gamma-ray detection
  20. GRB 260310A / AT 2026fgk: KAIT optical observations
  21. GRB 260320A: NuSTAR detection of prompt emission
  22. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  23. GRB 260310A/AT2026fgk: LBT near-infrared observations
  24. NOEMA Detection of GRB 260310A / AT 2026fgk
  25. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  26. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  27. GRB 260318A: Fermi GBM Final Real-time Localization
  28. GRB 260310A / AT 2026fgk: radio detection with the VLA
  29. GRB 260317A: Fermi GBM Final Localization
  30. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  31. GRB 260316B: AstroSat CZTI detection
  32. EP260316a: Xinglong optical upper limit
  33. GRB 260316B: Fermi GBM Final Real-time Localization
  34. EP260316a: optical upper limit with Kinder observations
  35. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  36. GRB 260314A: Glowbug gamma-ray detection
  37. EP260314a: Xinglong optical upper limit
  38. EP260314a: optical upper limit with Kinder observations
  39. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  40. GRB 260310A / AT 2026fgk: iTelescope optical observations
  41. GRID detection of GRB 260312B
  42. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  43. EP260314a: BOOTES-6/DPR optical upper limits at early times
  44. EP260314a: Einstein Probe detection of an X-ray transient
  45. GRB 260310A/AT2026fgk: radio detection at 15GHz
  46. GRB 260310A / AT2026fgk: TNG NIR detection
  47. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  48. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  49. GRB 260314A: Fermi GBM Final Real-time Localization
  50. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  51. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  52. GRB 260310B: Insight-HXMT/HE detection
  53. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  54. GRB 260312B: AstroSat CZTI detection
  55. Swift BAT trigger 1500295: A solar flare
  56. GRB 260313A: Fermi GBM Final Real-time Localization
  57. Swift BAT trigger 1500287: A solar flare
  58. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  59. GRB 260308A: Insight-HXMT/HE detection
  60. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  62. GRB260310A / AT2026fgk: P200 Spectroscopy
  63. GRB 260312B: Glowbug gamma-ray detection
  64. GRB 260310A: potential optical counterpart
  65. Swift BAT trigger 1500148: A solar flare
  66. GRB 260312B: Fermi GBM Final Real-time Localization
  67. GRB 260312A: Swift detection of a burst
  68. GRB 260311B: Fermi GBM Final Real-time Localization
  69. GRB 260131A/B: radio detection with the VLA
  70. GRB 260310A: AstroSat CZTI detection of a long burst
  71. GRB 260311A: Fermi GBM Final Real-time Localization
  72. GRB 260310B: Fermi GBM Final Real-time Localization
  73. GRB 260208A: radio detection with the VLA
  74. GRB 260310A: Fermi GBM Final Real-time Localization
  75. GRB 260307A: Glowbug gamma-ray detection
  76. GRB 260308A: Fermi GBM Final Real-time Localization
  77. Fermi GBM Sub-Threshold Detection of GRB 260307B
  78. GRB 260307B: Mephisto optical upper limits
  79. GRB 260307B: possible NOT optical counterpart
  80. GRB 260307B: SVOM/VT upper limit with X band data analysis
  81. GRB 260307B: SVOM/VT optical candidate
  82. GRB 260307B: SVOM detection of a burst
  83. GRB 260307A: Fermi GBM Final Localization
  84. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  85. GRB 260207A: TESS Detection and Possible VLA Counterpart
  86. EP260306a: Gemini-North redshift z = 4.773
  87. EP260306a: Einstein Probe detection of an X-ray transient
  88. EP260302a: Optical afterglow rebrightening
  89. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  90. GRB 260303A: 1.3m DFOT optical upper limit
  91. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  92. GRB 260305A: Fermi GBM Final Real-time Localization
  93. GRB 260303B: AstroSat CZTI detection
  94. GRB 260304A: AstroSat CZTI detection of a long burst
  95. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  96. GRB 260303A: SVOM/VT optical observations
  97. GRB 260303B: NuSTAR detection of prompt emission
  98. GRB 260303B: Fermi GBM Final Real-time Localization
  99. EP260302a: BOOTES-7 optical counterpart detection at early times
  100. GRB 260303A: SVOM detection of a burst

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