Skip to main content
Due to the lapse in federal government funding, NASA is not updating this website. See the Operations FAQ for GCN impacts.
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"
  1. GRB 230218A is not a GRB
  2. GRB 230218A: Fermi GBM Final Real-time Localization
  3. GRB 230217A: AGILE/MCAL detection
  4. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  5. GRB 230216B: AstroSat CZTI detection
  6. GRB 230216A: SVOM/C-GFT optical upper limit
  7. GRB 230217A: Swift detection of a short burst
  8. GRB 230217A: Fermi GBM Final Real-time Localization
  9. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 230216A: Swift-BAT refined analysis
  11. GRB 230216A: Swift-XRT refined Analysis
  12. GRB 230205A: Lowell Discovery Telescope Observations
  13. GRB 230204B: Lowell Discovery Telescope Observations
  14. Swift GRB 230216A: Global MASTER-Net observations report
  15. GRB 230216A: Enhanced Swift-XRT position
  16. GRB 230216A: AKO Upper Limit
  17. GRB 230216A: Zadko observatory - Gingin optical observations
  18. GRB 230216A: Swift detection of a burst
  19. Fermi GRB 230215A: Global MASTER-Net observations report
  20. GRB 230215A: Fermi GBM Final Real-time Localization
  21. GRB 230209B: AGILE detection
  22. GRB 230209B: Fermi GBM Observation
  23. IPN triangulation of GRB 230209B
  24. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  25. GRB 230204B: ATCA radio detection
  26. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  27. Fermi trigger No 697926015: Global MASTER-Net observations report
  28. Fermi trigger No 697904388: Global MASTER-Net observations report
  29. 230211A is not a GRB
  30. GRB 230211A: Fermi GBM Final Real-time Localization
  31. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  32. Fermi trigger No 697678542: Global MASTER-Net observations report
  33. Swift Trigger 1153670 is probably not a GRB
  34. GRB 230210A: Fermi GBM Final Real-time Localization
  35. Fermi GRB 230209B: Global MASTER-Net observations report
  36. GRB 230209B: Fermi GBM Final Real-time Localization
  37. GRB 230205A: 6 GHz VLA observations
  38. GRB 230209A is not a GRB
  39. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  40. GRB 230209A: Fermi GBM Final Real-time Localization
  41. GRB 221009A: Continued Swift Observations
  42. Fermi Gamma-ray Burst Monitor trigger 230208382/697540213 is not a GRB
  43. GRB 230207B: Detection by GRBAlpha
  44. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  45. GRB 230204B: MASTER early OT detection
  46. GRB 230208A: Fermi GBM Final Real-time Localization
  47. Fermi Gamma-ray Burst Monitor triggers 230206723/697396830 and 230206797/697403223 are not GRBs
  48. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  49. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  50. GRB 230207B: AGILE detection of a burst
  51. Fermi GRB 230207A: Global MASTER-Net observations report
  52. GRB 230207A: Fermi GBM Final Real-time Localization
  53. GRB 230204B: LCOGT Optical Upper Limits
  54. GRB 230204B: Swift/UVOT Upper Limits
  55. Fermi trigger No 697403223: Global MASTER-Net observations report
  56. Fermi trigger No 697396830: Global MASTER-Net observations report
  57. GRB 230205A: Swift/UVOT Upper Limits
  58. GRB 230204B: Fermi GBM detection
  59. Fermi Gamma-ray Burst Monitor triggers due to recent activity of RX J0440.9+4431 (LS V +44 17)
  60. GRB 230205A: LCOGT Optical Upper Limits
  61. GRB 230204B: Swift-XRT afterglow detection
  62. GRB 230204B: 3.6m DOT optical observation
  63. GRB 230205A: SVOM/C-GFT optical upper limit
  64. GRB 230205A: OHP/T193 optical observations
  65. GRB 230204B: VLT/X-shooter redshift
  66. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  67. GRB 230204A: Swift-BAT refined analysis
  68. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  69. GRB 230205A: Swift-XRT refined Analysis
  70. GRB 230204B: Swift ToO observations
  71. GRB 230205A: Enhanced Swift-XRT position
  72. GRB 230205A: BOOTES-5/JGT early optical upper limit
  73. GRB 230204B: Detection by GRBAlpha
  74. GRB 230204B: AGILE detection
  75. GRB 230205A: Swift detection of a burst
  76. IceCube-230201A: BOOTES-4/MET Optical Upper Limits
  77. GRB 230204B: GIT discovery of the likely optical afterglow
  78. GRB 230204B: AstroSat CZTI detection
  79. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  80. GRB 230204A: Swift/UVOT Upper Limits
  81. GRB 230204B: MAXI/GSC detection
  82. GRB 230204A: Swift-XRT refined Analysis
  83. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  84. Fermi trigger No 697208885: Global MASTER-Net observations report
  85. GRB 230204A: Enhanced Swift-XRT position
  86. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  87. GRB 230201B: TURBO Optical Upper Limits
  88. Fermi Gamma-ray Burst Monitor trigger 230203275 / 697098930 is not a GRB
  89. Fermi trigger No 697098930: Global MASTER-Net observations report
  90. IceCube-230201A: Upper limits from a search for additional neutrino events in IceCube
  91. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  92. GRB 221216A: Swift-BAT refined analysis
  93. ZTF23aabmzlp/AT2023azs: VLA radio detection
  94. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  95. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  96. IceCube Alert 230201.26: Global MASTER-Net observations report
  97. Fermi GRB 230201B: Global MASTER-Net observations report
  98. Fermi-LAT gamma-ray observations of IceCube-230201A
  99. GRB 230201B: Fermi GBM Final Real-time Localization
  100. GRB 230126A: Detection by VZLUSAT-2

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