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"

27343 results found.

  1. Fermi trigger No 795185313: Global MASTER-Net observations report
  2. IceCube Alert 260315A: Global MASTER-Net observations report
  3. EP260314a: Einstein Probe detection of an X-ray transient
  4. GRB 260310A / AT2026fgk: SAO RAS optical observations
  5. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  6. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  7. Fermi GRB 260314A: Global MASTER-Net observations report
  8. Fermi GRB 260313A: Global MASTER-Net observations report
  9. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  10. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  11. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  12. GRB 260312B: AstroSat CZTI detection
  13. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  14. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  15. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  16. GRB 260312B: Glowbug gamma-ray detection
  17. GRB 260310A: Fermi GBM Observation
  18. GRB 260310A: potential optical counterpart
  19. Fermi GRB 260312B: Global MASTER-Net observations report
  20. Fermi GRB 260311B: Global MASTER-Net observations report
  21. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  22. GRB 260131A/B: radio detection with the VLA
  23. EP260302a: MeerKAT radio counterpart
  24. GRB 260308A: SVOM/GRM observation of a short GRB
  25. EP260306a: Mondy optical upper limit
  26. Fermi GRB 260310B: Global MASTER-Net observations report
  27. Fermi GRB 260310A: Global MASTER-Net observations report
  28. GRB 260208A: radio detection with the VLA
  29. GRB 260307A: Glowbug gamma-ray detection
  30. Fermi GBM Sub-Threshold Detection of GRB 260307B
  31. GRB 260307B: Mephisto optical upper limits
  32. GRB 260307B: possible NOT optical counterpart
  33. GRB 260307B: SVOM/VT upper limit with X band data analysis
  34. Fermi GRB 260307A: Global MASTER-Net observations report
  35. GRB260307B: GROWTH-India Telescope optical upper limit
  36. GRB 260307B: SVOM/VT optical candidate
  37. GRB 260307B: SVOM/C-GFT upper limit
  38. GRB 260307B: SVOM detection of a burst
  39. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  40. GRB 260207A: TESS Detection and Possible VLA Counterpart
  41. EP260302a: SVOM/VT optical observation
  42. EP260306a: Gemini-North redshift z = 4.773
  43. EP260306a: SVOM/VT optical observation
  44. EP260302a: Gemini-South redshift z = 1.535
  45. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  46. EP260306a: Einstein Probe detection of an X-ray transient
  47. EP260302a: Optical afterglow rebrightening
  48. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  49. GRB 260303A: 1.3m DFOT optical upper limit
  50. Fermi GRB 260305A: Global MASTER-Net observations report
  51. GRB 260303B: AstroSat CZTI detection
  52. GRB 260303A: SVOM/VT optical observations
  53. GRB 260303A: J-band observations with WINTER
  54. GRB 260303B: NuSTAR detection of prompt emission
  55. EP260302a: Global MASTER-Net observations report
  56. Fermi GRB 260303B: Global MASTER-Net observations report
  57. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  58. EP260302a: analysis of the follow-up EP-FXT observation
  59. EP260302a: LCO observations
  60. EP260302a: BOOTES-7 optical counterpart detection at early times
  61. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  62. GRB 260303A: SVOM detection of a burst
  63. GRB 260228A: EP-FXT follow-up observation
  64. EP260302a: Einstein Probe detection of an X-ray transient
  65. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  66. GRB 251130B: TERI Gamma-ray detection
  67. GRB 260208A: TERI Gamma-ray detection
  68. EP260227a: Mondy optical observations
  69. GRB 260228A: CAHA 2.2m telescope optical upper limit
  70. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. EP260227a: Mephisto optical detection
  72. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  73. EP260227a: SVOM/VT optical observation
  74. GRB 260228A: SVOM/VT optical upper limits
  75. GRB 260225D: SVOM/GRM observation
  76. EP260227A: 3.6m DOT optical afterglow detection
  77. GRB 260225B: SVOM/GRM observation
  78. EP260227a: Liverpool Telescope optical observations
  79. EP260227a: LCOGT Optical Observations
  80. GRB 260226A: Asiago r-band upper limit
  81. EP260227a: Liverpool Telescope observations
  82. EP260227a: COLIBRÍ optical observations
  83. EP260227a: NOT optical observations
  84. EP260227a: Global MASTER-Net observations report
  85. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  86. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  87. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  88. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  89. EP260214a: VLT/FORS2 optical observations
  90. GRB 260225A: WINTER J-band upper limit
  91. GRB 260226A: COLIBRÍ optical upper limits
  92. GRB 260226A: LCOGT Optical Upper Limit
  93. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  94. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  95. GRB 260226A: Glowbug gamma-ray detection
  96. GRB 260226A: NuSTAR detection of bright prompt emission
  97. GRB 260226A : GROWTH-India Telescope optical observations
  98. GRB 260226A: LAST optical upper limit
  99. GRB 260226A: Fermi GBM observation
  100. LAT GRB260226.44: 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