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"
  1. GRB 230307A: Fermi GBM Final Real-time Localization
  2. Fermi trigger No 699811746: Global MASTER-Net observations report
  3. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  4. IceCube Alert 230306.46: Global MASTER-Net observations report
  5. GRB 230304C: AstroSat CZTI detection
  6. GRB 230304B: AstroSat CZTI detection
  7. GRB 230304A: AstroSat CZTI detection
  8. GRB 230304B: Detection by GRBAlpha
  9. GRB 230304C: Fermi GBM Final Real-time Localization
  10. GRB 230304B: Fermi GBM Final Real-time Localization
  11. GRB 230304A: Fermi GBM Final Real-time Localization
  12. GRB 230228A: 6 GHz VLA radio upper limit
  13. GRB 230228A: Swift-BAT refined analysis
  14. GRB 230228A: Swift/UVOT Upper Limits
  15. Fermi GRB 230301B: Global MASTER-Net observations report
  16. GRB 230301B: Fermi GBM Final Real-time Localization
  17. GRB 230228A: Fermi GBM Observation
  18. Fermi trigger No 699294715: Global MASTER-Net observations report
  19. GRB 230228A: OSN optical upper limit
  20. Fermi trigger No 699311646: Global MASTER-Net observations report
  21. GRB 230301A: Fermi GBM Final Real-time Localization
  22. GRB 230228A: Swift-XRT refined Analysis
  23. GRB 230228A: Mondy optical upper limit
  24. GRB 230228A: Enhanced Swift-XRT position
  25. GRB 230228A: Nanshan/NEXT optical upper limit
  26. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  27. GRB 230228A: Prompt enhanced Swift-XRT position
  28. GRB 230228A: Swift detection of a possibly short burst
  29. Fermi GRB 230227A: Global MASTER-Net observations report
  30. GRB 230227A: Fermi GBM Final Real-time Localization
  31. Fermi trigger No 699029364: Global MASTER-Net observations report
  32. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  33. GRB 230216A Mondy Observations
  34. GRB 230205A: VLA radio afterglow confirmation
  35. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 230217A: Swift/UVOT Upper Limits
  37. GRB 230216A: Swift/UVOT Upper Limits
  38. GRB 230217A: Continued Gemini Observations
  39. GRB 230220A: Correction to GCN 33352
  40. GRB 230222A: Fermi GBM Final Real-time Localization
  41. GRB 230217A: Swift-XRT afterglow detection
  42. Fermi-LAT gamma-ray observations of IceCube-230220A
  43. GRB 230217A: Swift-BAT refined analysis
  44. Fermi GRB 230220B: Global MASTER-Net observations report
  45. GRB 230217A: AstroSat CZTI detection
  46. GRB 230217A: Gemini South optical upper limits
  47. GRB 230216B: CALET Gamma-Ray Burst Monitor detection
  48. GRB 230217A: 6 GHz VLA observations
  49. GRB 230220B: Fermi GBM Final Real-time Localization
  50. GRB 230217A: Gemini-South Optical Observation
  51. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  52. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  53. GRB 230217A: Fermi GBM observation
  54. GRB 230220A: MAXI/GSC detection
  55. IceCube-230217A: BOOTES-4/MET Optical Observations
  56. Fermi-LAT gamma-ray observations of IceCube-230217A
  57. Konus-Wind detection of GRB 230217A
  58. GRB 230217A: Swift-XRT observations
  59. Fermi trigger No 698427992: Global MASTER-Net observations report
  60. IceCube Alert 230217.87: Global MASTER-Net observations report
  61. GRB 230218A is not a GRB
  62. GRB 230218A: Fermi GBM Final Real-time Localization
  63. GRB 230217A: AGILE/MCAL detection
  64. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  65. GRB 230216B: AstroSat CZTI detection
  66. GRB 230216A: SVOM/C-GFT optical upper limit
  67. GRB 230217A: Swift detection of a short burst
  68. GRB 230217A: Fermi GBM Final Real-time Localization
  69. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 230216A: Swift-BAT refined analysis
  71. GRB 230216A: Swift-XRT refined Analysis
  72. GRB 230205A: Lowell Discovery Telescope Observations
  73. GRB 230204B: Lowell Discovery Telescope Observations
  74. Swift GRB 230216A: Global MASTER-Net observations report
  75. GRB 230216A: Enhanced Swift-XRT position
  76. GRB 230216A: AKO Upper Limit
  77. GRB 230216A: Zadko observatory - Gingin optical observations
  78. GRB 230216A: Swift detection of a burst
  79. Fermi GRB 230215A: Global MASTER-Net observations report
  80. GRB 230215A: Fermi GBM Final Real-time Localization
  81. GRB 230209B: AGILE detection
  82. GRB 230209B: Fermi GBM Observation
  83. IPN triangulation of GRB 230209B
  84. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  85. GRB 230204B: ATCA radio detection
  86. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  87. Fermi trigger No 697926015: Global MASTER-Net observations report
  88. Fermi trigger No 697904388: Global MASTER-Net observations report
  89. 230211A is not a GRB
  90. GRB 230211A: Fermi GBM Final Real-time Localization
  91. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  92. Fermi trigger No 697678542: Global MASTER-Net observations report
  93. Swift Trigger 1153670 is probably not a GRB
  94. GRB 230210A: Fermi GBM Final Real-time Localization
  95. Fermi GRB 230209B: Global MASTER-Net observations report
  96. GRB 230209B: Fermi GBM Final Real-time Localization
  97. GRB 230205A: 6 GHz VLA observations
  98. GRB 230209A is not a GRB
  99. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  100. GRB 230209A: 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