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"

23559 results found.

  1. GRB 260506B: AstroSat CZTI detection
  2. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  3. EP260507a: REM optical/NIR observations
  4. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  5. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  6. EP260507a: SVOM/VT optical observations
  7. GRB 260507A: Fermi GBM Final Real-time Localization
  8. EP260507a: TRT optical counterpart detection
  9. GRB 260504B: SVOM/ECLAIRs refined analysis
  10. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  11. GRB 260506B: Fermi GBM Final Real-time Localization
  12. EP260502a is likely a flaring star
  13. Fermi GRB 260506A: Global MASTER-Net observations report
  14. GRB 260506A: Fermi GBM Final Real-time Localization
  15. IceCube Alert 260505A: Global MASTER-Net observations report
  16. GRB 260504B: SVOM/VT optical upper limits
  17. Konus-Wind detection of GRB 260504B (short/hard)
  18. GRB 260504B: GECAM-B detection
  19. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  20. GRB 260504B: SVOM/GRM spectral analysis
  21. GRB 260504B: SVOM/MXT refined analysis and potential detection
  22. GRB 260504B: EP-FXT upper limit
  23. GRB 260502A: SVOM/GRM observation of a short GRB
  24. GRB 260503A: SVOM/GRM observation of a GRB
  25. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  26. Konus-Wind detection of GRB 260415C
  27. Konus-Wind detection of GRB 260411C
  28. GRB 260504B: REM optical/NIR observations
  29. IPN triangulation of GRB 260429A
  30. IPN triangulation of GRB 260428A
  31. GRB 260504B: AST3-2 i-band upper limit
  32. GRB 260504B: LCO z-band upper limit
  33. SVOM GRB 260504B: MASTER-OAFA optical observations
  34. GRB 260504B: SVOM detection of a short burst
  35. Fermi GRB 260504A: Global MASTER-Net observations report
  36. GRB 260504A: Fermi GBM Final Real-time Localization
  37. GRB 260503A: Fermi GBM Final Real-time Localization
  38. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  39. IPN triangulation of a bright burst from SGR 1E1841-045
  40. GRB 260502A: Fermi GBM Final Localization
  41. The EP-WXT trigger 01709261576 is likely a flaring star
  42. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  43. EP260502a: BOOTES-7: early optical upper limit
  44. GRB 260429A: SVOM/GRM observation of a short burst
  45. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  46. EP260429a: Global MASTER-Net observations report
  47. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  48. GRB 260429A: Fermi GBM Detection
  49. Fermi GRB 260429A: Global MASTER-Net observations report
  50. EP260430a: Global MASTER-Net observations report
  51. GRB 260429A: Fermi GBM Final Real-time Localization
  52. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  53. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  54. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  55. Fermi GRB 260428A: Global MASTER-Net observations report
  56. Konus-Wind detection of GRB 260424B
  57. GRB 260428A: Fermi GBM Final Real-time Localization
  58. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  59. GRB 260424C: Fermi GBM Final Localization
  60. IPN triangulation of GRB 260424B (short)
  61. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  62. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  63. IceCube Alert 260425A: Global MASTER-Net observations report
  64. Fermi trigger No 798737427: Global MASTER-Net observations report
  65. GRB 260401A: cubesat Avion detection
  66. GRB 260424A: AstroSat CZTI detection of a long burst
  67. GRB 260421B: SVOM/ECLAIRs refined analysis
  68. GRB 260421B: 3.6m DOT optical observation
  69. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  71. GRB 260421B: SVOM/GRM observation
  72. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  73. GRB 260421B: EP-FXT follow-up observation
  74. The EP-WXT trigger 01709260362 is likely a flaring star
  75. GRB 260421B: Fermi GBM Observation
  76. GRB 260412A: SVOM/ECLAIRs refined analysis
  77. GRB 260421B: SVOM/VT optical observations
  78. GRB 260310A: Late-time Chandra X-ray Detection
  79. EP260416a: 1.3m DFOT optical observation
  80. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  82. Fermi GRB 260421C: Global MASTER-Net observations report
  83. GRB 260421C: Fermi GBM Final Real-time Localization
  84. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  85. Fermi GRB 260421B: Global MASTER-Net observations report
  86. GRB 260421B: LCO optical afterglow confirmation
  87. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  88. GRB 260421B: TRT optical counterpart detection
  89. GRB 260421B: SVOM detection of a long burst
  90. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  91. GRB 260421B: Fermi GBM Final Real-time Localization
  92. Fermi GRB 260421A: Global MASTER-Net observations report
  93. GRB 260421A: Fermi GBM Final Real-time Localization
  94. GRB 260412A: LCOGT Optical Upper Limits
  95. The EP-WXT trigger 01709260314 is likely a flaring star
  96. The EP-WXT trigger 01709260303 is likely a flaring star
  97. GRB 260417A: SVOM/GRM observation
  98. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  99. GRB 260419B: Fermi GBM Final Real-time Localization
  100. GRB 260419A: Fermi GBM Final Real-time Localization

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