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"

28117 results found.

  1. EP260327a: SVOM/VT optical upper limits
  2. EP260327a: WINTER J-band upper limit
  3. EP260327a: COLIBRÍ optical upper limits
  4. EP260327a: Gemini-North optical upper limits
  5. EP260324a: GROWTH-India Telescope optical observation
  6. EP260327a: Global MASTER-Net observations report
  7. EP260327a: Einstein Probe detection of an X-ray transient
  8. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  9. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  10. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  11. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  12. GRB 260326A: Fermi GBM Detection
  13. EP260321a: JinShan near-infrared observations
  14. EP260321a: Upper limits from a neutrino search with IceCube
  15. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  16. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  17. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  18. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  19. Fermi GRB 260323A: Global MASTER-Net observations report
  20. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  21. GRB 260320A: Glowbug gamma-ray detection
  22. EP260321a: COLIBRÍ further optical observations and brightening
  23. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  24. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  25. GRB 260321A: EP-FXT follow-up observation
  26. EP260321a: GOTO detection of blue variable source
  27. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  28. EP260321a: further Kinder optical observations
  29. GRB 260321A: SVOM/VT optical upper limits
  30. EP260321a: Las Cumbres upper limit
  31. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  33. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  34. EP260321a: SVOM/VT optical upper limit
  35. Fermi GBM Sub-Threshold Detection of GRB 260321A
  36. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  37. EP260321a: Global MASTER-Net observations report
  38. EP260321a: Einstein Probe detection of an X-ray transient
  39. GRB 260318A: Glowbug gamma-ray detection
  40. GRB 260310A / AT 2026fgk: KAIT optical observations
  41. GRB 260320A: NuSTAR detection of prompt emission
  42. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  43. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  44. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  45. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  46. GRB 260318A: SVOM/GRM observation
  47. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  48. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  49. Fermi GRB 260318A: Global MASTER-Net observations report
  50. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  51. GRB 260310A / AT 2026fgk: radio detection with the VLA
  52. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  53. GRB 260310A / AT2026fgk: LCO optical observations
  54. GRB 260316B: SVOM/GRM observation
  55. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  56. EP260316a: COLIBRÍ faint optical counterpart candidate
  57. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  58. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  59. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  60. EP260316a: Xinglong optical upper limit
  61. EP260316a: optical upper limit with Kinder observations
  62. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  63. GRB 260314A: Glowbug gamma-ray detection
  64. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  65. IceCube-260315A: COLIBRÍ optical observations
  66. EP260314a: Xinglong optical upper limit
  67. EP260314a: optical upper limit with Kinder observations
  68. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  69. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  70. GRB 260310A / AT 2026fgk: iTelescope optical observations
  71. EP260314a: COLIBRÍ optical upper limit
  72. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  73. EP260314a: Global MASTER-Net observations report
  74. EP260314a: SVOM/VT optical candidate
  75. Fermi trigger No 795185313: Global MASTER-Net observations report
  76. IceCube Alert 260315A: Global MASTER-Net observations report
  77. EP260314a: Einstein Probe detection of an X-ray transient
  78. GRB 260310A / AT2026fgk: SAO RAS optical observations
  79. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  80. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  81. Fermi GRB 260314A: Global MASTER-Net observations report
  82. Fermi GRB 260313A: Global MASTER-Net observations report
  83. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  84. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  85. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  86. GRB 260312B: AstroSat CZTI detection
  87. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  88. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  89. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  90. GRB 260312B: Glowbug gamma-ray detection
  91. GRB 260310A: Fermi GBM Observation
  92. GRB 260310A: potential optical counterpart
  93. Fermi GRB 260312B: Global MASTER-Net observations report
  94. Fermi GRB 260311B: Global MASTER-Net observations report
  95. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  96. GRB 260131A/B: radio detection with the VLA
  97. EP260302a: MeerKAT radio counterpart
  98. GRB 260308A: SVOM/GRM observation of a short GRB
  99. EP260306a: Mondy optical upper limit
  100. Fermi GRB 260310B: Global MASTER-Net observations report

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