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"

45717 results found.

  1. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  2. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  3. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  4. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  5. GRB 260310A/AT2026fgk: LBT near-infrared observations
  6. NOEMA Detection of GRB 260310A / AT 2026fgk
  7. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  8. GRB 260318A: SVOM/GRM observation
  9. The EP-WXT trigger 01709258989 is likely a flaring star
  10. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  11. GRB 260318A: GECAM-B observation
  12. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  13. Fermi GRB 260318A: Global MASTER-Net observations report
  14. GRB 260318A: Fermi GBM Final Real-time Localization
  15. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  16. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  17. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  18. GRB 260310A / AT 2026fgk: radio detection with the VLA
  19. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  20. GRB 260310A / AT2026fgk: LCO optical observations
  21. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  22. GRB 260317A: Fermi GBM Final Localization
  23. GRB 260316B: GECAM-B observation
  24. GRB 260316B: SVOM/GRM observation
  25. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  26. EP260316a: COLIBRÍ faint optical counterpart candidate
  27. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  28. GRB 260316B: AstroSat CZTI detection
  29. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  30. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  31. EP260316a: Xinglong optical upper limit
  32. GRB 260316B: Fermi GBM Final Real-time Localization
  33. EP260316a: optical upper limit with Kinder observations
  34. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  35. GRB 260314A: Glowbug gamma-ray detection
  36. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  37. IceCube-260315A: COLIBRÍ optical observations
  38. EP260314a: Xinglong optical upper limit
  39. EP260314a: optical upper limit with Kinder observations
  40. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  41. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  42. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  43. GRB 260310A / AT 2026fgk: iTelescope optical observations
  44. EP260314a: COLIBRÍ optical upper limit
  45. GRID detection of GRB 260312B
  46. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  47. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  48. EP260314a: BOOTES-6/DPR optical upper limits at early times
  49. EP260314a: Global MASTER-Net observations report
  50. EP260314a: SVOM/VT optical candidate
  51. Fermi trigger No 795185313: Global MASTER-Net observations report
  52. IceCube Alert 260315A: Global MASTER-Net observations report
  53. EP260314a: Einstein Probe detection of an X-ray transient
  54. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  55. GRB 260314A: GECAM-B observation of a burst
  56. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  57. GRB 260310A / AT2026fgk: SAO RAS optical observations
  58. GRB 260310A/AT2026fgk: radio detection at 15GHz
  59. GRB 260310A / AT2026fgk: TNG NIR detection
  60. GRB 260310A / AT2026fgk: OASDG optical observations
  61. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  62. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  63. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  64. Fermi GRB 260314A: Global MASTER-Net observations report
  65. Fermi GRB 260313A: Global MASTER-Net observations report
  66. GRB 260314A: Fermi GBM Final Real-time Localization
  67. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  68. GRB 260313A: A Correction to the Fermi GBM Final Localization
  69. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  70. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  71. GRB 260310B: Insight-HXMT/HE detection
  72. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  73. GRB 260310A: NOT optical polarimetry
  74. GRB 260312B: AstroSat CZTI detection
  75. Swift BAT trigger 1500295: A solar flare
  76. GRB 260313A: Fermi GBM Final Real-time Localization
  77. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  78. Swift BAT trigger 1500287: A solar flare
  79. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  80. GRB 260308A: Insight-HXMT/HE detection
  81. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  83. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  84. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  85. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  86. GRB260310A / AT2026fgk: P200 Spectroscopy
  87. GRB 260312B: Glowbug gamma-ray detection
  88. GRB 260310A: Fermi GBM Observation
  89. GRB 260310A: potential optical counterpart
  90. Fermi GRB 260312B: Global MASTER-Net observations report
  91. Fermi GRB 260311B: Global MASTER-Net observations report
  92. Swift BAT trigger 1500148: A solar flare
  93. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  94. GRB 260312B: Fermi GBM Final Real-time Localization
  95. The EP-WXT trigger 01709258843 is not a real source
  96. GRB 260310B: GECAM-B observation of a burst
  97. Retraction of GCN 43965: GRB is actually solar flare
  98. GRB 260312A: Swift detection of a burst
  99. GRB 260311B: Fermi GBM Final Real-time Localization
  100. GRB 260131A/B: radio detection with the VLA

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