Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

6791 results found.

  1. GRB 260614B: Fermi GBM Observation
  2. GRB 260610B: Fermi GBM Observation
  3. GRB 260610B / AT2026owq: further SAO RAS optical observations
  4. IceCube-260610A: EP-FXT follow-up observation
  5. GRB 260610B / AT2026owq: OASDG optical observations
  6. GRB 260610B / AT2026owq: SAO RAS optical observations
  7. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  8. GRB 260608A: Fermi GRB Observation
  9. GRB 260604C: further SAO RAS optical observations
  10. EP260605a: EP-FXT follow-up observation
  11. GRB 260607B: Fermi GBM Observation
  12. GRB 260607B: Fermi-LAT detection
  13. GRB 260604C: SAO RAS optical observations
  14. EP260602d: EP-FXT follow-up observation
  15. EP260602c: EP-FXT follow-up observation
  16. GRB 260604C: Fermi GBM Observation
  17. EP260602a: EP-FXT follow-up observation
  18. EP260602d: Optical Upper limits with kinder observations
  19. GRB 260603A: EP-FXT follow-up observation
  20. EP260601a/GRB 260601B: EP-FXT follow-up observation
  21. EP260602b: EP-FXT follow-up observation
  22. EP260602a: Optical upper limits with Kinder observations
  23. GRB 260601A: Fermi GBM Observation
  24. AT2026nik: EP-FXT X-ray counterpart
  25. EP260527a/GRB 260527A: EP-FXT follow-up observation
  26. EP260526a: EP-FXT follow-up observation
  27. GRB 260522A: Fermi GBM Observation
  28. GRB 260522A: Fermi-LAT detection
  29. Konus-Wind detection of GRB 260515A
  30. GRB 260515A: EP-FXT follow-up observation
  31. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  32. GRB 260515A: NOT optical observations.
  33. GRB 260511B: Mephisto multi-band optical followup
  34. EP260512a: EP-FXT follow-up observation
  35. Konus-Wind detection of GRB 260511B
  36. GRB 260511B: SAO RAS optical observations
  37. GRB 260511B: EP-FXT follow-up observation
  38. GRB 260511B: LCO optical counterpart detection
  39. GRB 260510B: EP-FXT follow-up observation
  40. GRB 260510C: Fermi GBM Observation
  41. GRB 260509A: SAO RAS optical observations
  42. GRB 260511B: Fermi GBM Detection
  43. GRB 260511A: Fermi GBM Detection
  44. Fermi GRB 260511A: Global MASTER-Net observations report
  45. EP260507a: NOT optical observations
  46. EP260507a: Kinder optical counterpart candidate
  47. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  48. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  49. GRB 260429A: Fermi GBM Detection
  50. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  51. GRB 260421B: Fermi GBM Observation
  52. GRB 260310A: Late-time Chandra X-ray Detection
  53. EP260416a: Optical follow-up observations with Kinder
  54. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  55. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  56. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  57. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  58. GRB 260410A: Insight-HXMT/HE detection
  59. GRB 260412A: Fermi GBM Observation
  60. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  61. GRB 260411B: Fermi-LAT detection
  62. GRB 260410B: Fermi GBM Observation
  63. GRB 260409A: Insight-HXMT/HE detection
  64. GRB 260411B: Fermi GBM Detection
  65. EP-WXT01709259790: Optical Upper limits with kinder observations
  66. GRB 260410A: Fermi GBM Observation
  67. GRB 260410A: Fermi-LAT detection
  68. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  69. EP260321a: Chandra X-ray Non-detection
  70. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  71. GRB 260401A: Fermi GBM Observation
  72. EP260321a :Xinglong optical observations
  73. EP260329a: NOT optical counterpart candidate
  74. EP260329b: Optical follow-up with Kinder observations
  75. EP260329a: Optical upper limit with Kinder observations
  76. EP260329b: LCO optical observations of the counterpart
  77. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  78. GRB 260326A: Fermi GBM Detection
  79. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  80. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  81. EP260321a: further Kinder optical observations
  82. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  83. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  84. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  85. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  86. EP260316a: optical upper limit with Kinder observations
  87. EP260314a: optical upper limit with Kinder observations
  88. GRB 260310A / AT 2026fgk: iTelescope optical observations
  89. Fermi trigger No 795185313: Global MASTER-Net observations report
  90. IceCube Alert 260315A: Global MASTER-Net observations report
  91. GRB 260310A / AT2026fgk: SAO RAS optical observations
  92. GRB 260310A / AT2026fgk: OASDG optical observations
  93. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  94. Fermi GRB 260314A: Global MASTER-Net observations report
  95. GRB 260310A: Fermi GBM Observation
  96. GRB 260303A: 1.3m DFOT optical upper limit
  97. EP260302a: LCO observations
  98. EP260227a: further LCO observations
  99. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  100. GRB 260226A : GROWTH-India Telescope optical observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov