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"

41631 results found.

  1. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  2. GRB 260509A: LCO optical observations
  3. SVOM GRB 260509A: MASTER-OAFA optical observation
  4. Fermi GRB 260510A: Global MASTER-Net observations report
  5. GRB 260509A: KAIT optical observations
  6. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  7. GRB 260510A: Fermi GBM Final Real-time Localization
  8. GRB 260509A: SVOM/VT optical candidate with VHF data
  9. GRB 260509A: LCO optical counterpart detection
  10. GRB 260509A: GOTO optical counterpart candidate
  11. GRB 260509A: SVOM detection of a burst
  12. GRB 260506B: AstroSat CZTI detection
  13. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  14. EP260507a: REM optical/NIR observations
  15. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  16. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  17. EP260507a: COLIBRÍ optical observations
  18. EP260507a: SVOM/VT optical observations
  19. EP260507a: NOT optical observations
  20. EP260507a: further Liverpool Telescope observations
  21. EP260507a: Liverpool Telescope optical upper limits
  22. GRB 260507A: Fermi GBM Final Real-time Localization
  23. EP260507a: GOTO optical counterpart detection
  24. EP260507a: TRT optical counterpart detection
  25. EP260507a: Kinder optical counterpart candidate
  26. EP260507a: LCO optical counterpart
  27. EP260507a: Einstein Probe detection of an X-ray transient
  28. GRB 260504B: AstroSat CZTI detection
  29. GRB 260504B: SVOM/ECLAIRs refined analysis
  30. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  31. GRB 260506B: Fermi GBM Final Real-time Localization
  32. EP260502a is likely a flaring star
  33. Fermi GRB 260506A: Global MASTER-Net observations report
  34. GRB 260506A: Fermi GBM Final Real-time Localization
  35. GRB 260503A: GECAM-B observation of a burst
  36. IceCube Alert 260505A: Global MASTER-Net observations report
  37. GRB 260430B: Glowbug gamma-ray detection
  38. GRB 260504B: SVOM/VT optical upper limits
  39. GRB 260421B: radio observation with the VLA
  40. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  41. Konus-Wind detection of GRB 260504B (short/hard)
  42. GRB 260504B: GECAM-B detection
  43. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  44. GRB 260504C: SVOM/GRM observation of short GRB
  45. GRB 260504B: SVOM/GRM spectral analysis
  46. GRB 260430B: AstroSat CZTI detection of a long burst
  47. GRB 260504B: SVOM/MXT refined analysis and potential detection
  48. GRB 260504B: EP-FXT upper limit
  49. GRB 260502A: SVOM/GRM observation of a short GRB
  50. GRB 260503A: SVOM/GRM observation of a GRB
  51. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  52. Konus-Wind detection of GRB 260415C
  53. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  54. Konus-Wind detection of GRB 260411C
  55. GRB 260504B: REM optical/NIR observations
  56. IPN triangulation of GRB 260429A
  57. IPN triangulation of GRB 260428A
  58. GRB 260504B: AST3-2 i-band upper limit
  59. GRB 260504B: LCO z-band upper limit
  60. SVOM GRB 260504B: MASTER-OAFA optical observations
  61. GRB 260504B: SVOM detection of a short burst
  62. Fermi GRB 260504A: Global MASTER-Net observations report
  63. GRB 260504A: Fermi GBM Final Real-time Localization
  64. GRB 260503A: Fermi GBM Final Real-time Localization
  65. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  66. GRB 260502A: GECAM-B observation of a short burst
  67. IPN triangulation of a bright burst from SGR 1E1841-045
  68. GRB 260502A: Fermi GBM Final Localization
  69. The EP-WXT trigger 01709261576 is likely a flaring star
  70. GRB 260429B / EP260429a: EP-FXT follow-up observation
  71. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  72. GRB 260429B / EP260429a: AstroSat CZTI detection
  73. EP260502a: BOOTES-7: early optical upper limit
  74. EP260502a: Einstein Probe detection of an X-ray transient
  75. GRB 260429A: SVOM/GRM observation of a short burst
  76. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  77. EP260429a: Global MASTER-Net observations report
  78. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  79. GRB 260424B: AstroSat CZTI detection
  80. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  81. EP260429a: LCO optical upper limits
  82. EP260430a: LCO optical upper limits
  83. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  84. GRB 260429A: Fermi GBM Detection
  85. Fermi GRB 260429A: Global MASTER-Net observations report
  86. EP260430a: Global MASTER-Net observations report
  87. EP260430a: Einstein Probe detection of an X-ray transient
  88. EP260429a: EP-WXT detection of a fast X-ray transient
  89. GRB 260429A: Fermi GBM Final Real-time Localization
  90. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  91. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  92. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  93. GRB 260428A: AstroSat CZTI detection
  94. Fermi GRB 260428A: Global MASTER-Net observations report
  95. EP260416a: Mondy and Terskol optical upper limits
  96. GRB 260424B: Glowbug gamma-ray detection of a short burst
  97. GRB 260424B: COLIBRÍ optical upper limit
  98. Konus-Wind detection of GRB 260424B
  99. GRB 260428A: Fermi GBM Final Real-time Localization
  100. Fermi-LAT Gamma-ray Observations of IceCube-260425A

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