Skip to main content
Retirement of GCN Classic VOEvent Brokers. 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"

26959 results found.

  1. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  2. EP260316a: Xinglong optical upper limit
  3. EP260316a: optical upper limit with Kinder observations
  4. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  5. GRB 260314A: Glowbug gamma-ray detection
  6. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  7. IceCube-260315A: COLIBRÍ optical observations
  8. EP260314a: Xinglong optical upper limit
  9. EP260314a: optical upper limit with Kinder observations
  10. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  11. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  12. GRB 260310A / AT 2026fgk: iTelescope optical observations
  13. EP260314a: COLIBRÍ optical upper limit
  14. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  15. EP260314a: Global MASTER-Net observations report
  16. EP260314a: SVOM/VT optical candidate
  17. Fermi trigger No 795185313: Global MASTER-Net observations report
  18. IceCube Alert 260315A: Global MASTER-Net observations report
  19. EP260314a: Einstein Probe detection of an X-ray transient
  20. GRB 260310A / AT2026fgk: SAO RAS optical observations
  21. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  22. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  23. Fermi GRB 260314A: Global MASTER-Net observations report
  24. Fermi GRB 260313A: Global MASTER-Net observations report
  25. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  26. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  27. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  28. GRB 260312B: AstroSat CZTI detection
  29. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  30. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  31. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  32. GRB 260312B: Glowbug gamma-ray detection
  33. GRB 260310A: Fermi GBM Observation
  34. GRB 260310A: potential optical counterpart
  35. Fermi GRB 260312B: Global MASTER-Net observations report
  36. Fermi GRB 260311B: Global MASTER-Net observations report
  37. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  38. GRB 260131A/B: radio detection with the VLA
  39. EP260302a: MeerKAT radio counterpart
  40. GRB 260308A: SVOM/GRM observation of a short GRB
  41. EP260306a: Mondy optical upper limit
  42. Fermi GRB 260310B: Global MASTER-Net observations report
  43. Fermi GRB 260310A: Global MASTER-Net observations report
  44. GRB 260208A: radio detection with the VLA
  45. GRB 260307A: Glowbug gamma-ray detection
  46. Fermi GBM Sub-Threshold Detection of GRB 260307B
  47. GRB 260307B: Mephisto optical upper limits
  48. GRB 260307B: possible NOT optical counterpart
  49. GRB 260307B: SVOM/VT upper limit with X band data analysis
  50. Fermi GRB 260307A: Global MASTER-Net observations report
  51. GRB260307B: GROWTH-India Telescope optical upper limit
  52. GRB 260307B: SVOM/VT optical candidate
  53. GRB 260307B: SVOM/C-GFT upper limit
  54. GRB 260307B: SVOM detection of a burst
  55. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  56. GRB 260207A: TESS Detection and Possible VLA Counterpart
  57. EP260302a: SVOM/VT optical observation
  58. EP260306a: Gemini-North redshift z = 4.773
  59. EP260306a: SVOM/VT optical observation
  60. EP260302a: Gemini-South redshift z = 1.535
  61. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  62. EP260306a: Einstein Probe detection of an X-ray transient
  63. EP260302a: Optical afterglow rebrightening
  64. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  65. GRB 260303A: 1.3m DFOT optical upper limit
  66. Fermi GRB 260305A: Global MASTER-Net observations report
  67. GRB 260303B: AstroSat CZTI detection
  68. GRB 260303A: SVOM/VT optical observations
  69. GRB 260303A: J-band observations with WINTER
  70. GRB 260303B: NuSTAR detection of prompt emission
  71. EP260302a: Global MASTER-Net observations report
  72. Fermi GRB 260303B: Global MASTER-Net observations report
  73. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  74. EP260302a: analysis of the follow-up EP-FXT observation
  75. EP260302a: LCO observations
  76. EP260302a: BOOTES-7 optical counterpart detection at early times
  77. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  78. GRB 260303A: SVOM detection of a burst
  79. GRB 260228A: EP-FXT follow-up observation
  80. EP260302a: Einstein Probe detection of an X-ray transient
  81. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  82. GRB 251130B: TERI Gamma-ray detection
  83. GRB 260208A: TERI Gamma-ray detection
  84. EP260227a: Mondy optical observations
  85. GRB 260228A: CAHA 2.2m telescope optical upper limit
  86. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. EP260227a: Mephisto optical detection
  88. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  89. EP260227a: SVOM/VT optical observation
  90. GRB 260228A: SVOM/VT optical upper limits
  91. GRB 260225D: SVOM/GRM observation
  92. EP260227A: 3.6m DOT optical afterglow detection
  93. GRB 260225B: SVOM/GRM observation
  94. EP260227a: Liverpool Telescope optical observations
  95. EP260227a: LCOGT Optical Observations
  96. GRB 260226A: Asiago r-band upper limit
  97. EP260227a: Liverpool Telescope observations
  98. EP260227a: COLIBRÍ optical observations
  99. EP260227a: NOT optical observations
  100. EP260227a: Global MASTER-Net observations report

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