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"
  1. GRB210610A: MeerLICHT multi-colour photometry
  2. Swift GRB 210610A: Global MASTER-Net observations report
  3. Swift GRB 210610A: MASTER optical counterpart observation
  4. GRB 210610A: Enhanced Swift-XRT position
  5. GRB 210610A: Xinglong-2.16m redshift
  6. GRB 210610A: GIT optical detection
  7. GRB 210610A: Xinglong-2.16m optical afterglow observations
  8. GRB 210610A: MITSuME Akeno optical observation
  9. GRB 210610A: Swift detection of a burst with an optical counterpart
  10. GRB 210607B: Insight-HXMT/HE detection
  11. GRB 210605A: CALET Gamma-Ray Burst Monitor detection
  12. Konus-Wind detection of GRB 210606B
  13. Fermi-LAT Gamma-ray Observations of IceCube-210608A
  14. IceCube-210608A: not observable by Fermi-GBM
  15. IPN triangulation of GRB 210606B
  16. IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
  17. IceCube Alert 210608.15: Global MASTER-Net observations report
  18. Fermi Gamma-ray Burst Monitor trigger 644793834 / 210607892 is not a GRB
  19. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  20. MAXI GRB210607.82: Global MASTER-Net observations report
  21. Fermi trigger No 644793834: Global MASTER-Net observations report
  22. GRB 210606B: Fermi GBM detection
  23. GRB 210605B: Swift-XRT observations
  24. Konus-Wind detection of GRB 210602A
  25. Konus-Wind detection of GRB 210605A (short/hard)
  26. IPN triangulation of GRB 210605A (short)
  27. GRB 210606B: AGILE detection
  28. GRB 210606A: 1.5m OSN optical upper limit
  29. GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402
  30. GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
  31. GRB 210606B: GECAM detection
  32. Fermi trigger No 644712030: Global MASTER-Net observations report
  33. GRB 210606A: Swift ToO observations
  34. Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
  35. GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
  36. GRB 210605B: Swift ToO observations
  37. Fermi GRB 210606A: Global MASTER-Net observations report
  38. GRB 210606A: Fermi GBM Final Real-time Localization
  39. GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
  40. GRB 210605B: Fermi GBM Final Real-time Localization
  41. Fermi GRB 210605A: Global MASTER-Net observations report
  42. GRB 210605A: Fermi GBM Final Real-time Localization
  43. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  44. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  45. SGR J1555.2-5402: Swift-BAT refined analysis
  46. Fermi trigger No 644449593: Global MASTER-Net observations report
  47. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  48. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  49. Swift Detection of probable new Swift SGR J1555.2-5402
  50. MAXI GRB210602.50: Global MASTER-Net observations report
  51. Swift GRB210603.41: Global MASTER-Net observations report
  52. GRB 210602A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 210602B: GECAM detection
  54. GRB 210529A: GECAM detection
  55. Fermi trigger No 644359567: Global MASTER-Net observations report
  56. GRB 210602A: MAXI/GSC detection
  57. Fermi GRB 210601A: Global MASTER-Net observations report
  58. GRB 210601A: Fermi GBM Final Real-time Localization
  59. IPN triangulation of GRB 210531A
  60. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  61. GRB 210531A: AstroSat CZTI detection
  62. Fermi trigger No 644155206: Global MASTER-Net observations report
  63. GRB 210531A: AGILE/MCAL detection (Fermi Trigger 644155206 / GRB 210531500)
  64. GRB 210531A: BALROG localization (Fermi Trigger 644155206 / GRB 210531500)
  65. GRB 210529B: DDOTI Upper Limits on the Afterglow
  66. Fermi GRB 210529A: Global MASTER-Net observations report
  67. Fermi GRB 210529B: Global MASTER-Net observations report
  68. GRB 210529B: Fermi GBM Final Real-time Localization
  69. GRB 210529A: Fermi GBM Final Real-time Localization
  70. GRB 210528A: Fermi GBM detection
  71. GRB 210528A: AstroSat CZTI detection
  72. GRB 210528B: DDOTI Upper Limits on the Afterglow
  73. GRB 210528B: MITSuME Akeno optical upper limits
  74. MAXI GRB210528.95: Global MASTER-Net observations report
  75. GRB 210528B: MAXI/GSC detection
  76. Fermi GRB 210528A: Global MASTER-Net observations report
  77. GRB 210527A: Swift-BAT refined analysis
  78. GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
  79. GRB 210528A: Fermi GBM Final Real-time Localization
  80. GRB 210527A: Swift/UVOT Observations
  81. GRB 210527A: GIT optical upper limit
  82. GRB 210527A: MITSuME Akeno optical upper limits
  83. Swift GRB 210527A: Global MASTER-Net observations report
  84. GRB 210527A: Swift-XRT refined Analysis
  85. GRB 210527A: RATIR Optical and NIR Observations
  86. GRB 210527A: Enhanced Swift-XRT position
  87. GRB 210527A: Swift-XRT observations
  88. GRB 210527A: Swift detection of a burst
  89. GRB 210306A: LBT observations of the likely host galaxy
  90. ZTF21aayokph (AT2021lfa): LBT optical observations
  91. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  92. Konus-Wind detection of GRB 210524A
  93. IPN triangulation of GRB 210524A
  94. Fermi trigger No 643548039: Global MASTER-Net observations report
  95. GRB 210524B: Fermi GBM Final Real-time Localization
  96. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  97. Fermi GRB 210524A: Global MASTER-Net observations report
  98. GRB 210524A: Fermi GBM Final Real-time Localization
  99. GRB 210522A: GECAM detection
  100. GRB 210520A: Swift-XRT observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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