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. GRB 210108A: BALROG localization (Fermi Trigger 631793415 / GRB 210108424)
  2. GRB 201216C: Swift-XRT refined Analysis
  3. GRB 210104A: SAO RAS optical observations
  4. GRB 201227A: ASIM observation
  5. GRB 210104A: GMG observations
  6. GRB210104A: VIRT optical transient detection.
  7. GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection
  8. Fermi trigger No 631602681: Global MASTER-Net observations report
  9. GRB 210102B: further Swift-XRT observations
  10. GRB 210102B: Assy optical afterglow identification
  11. GRB 210104A: iTelescope optical upper limit
  12. GRB 210104A: CALET Gamma-Ray Burst Monitor detection
  13. Fermi trigger No 631584650: Global MASTER-Net observations report
  14. GRB 210104B: Swift-BAT refined analysis
  15. GRB 210104A: Assy continued optical observations
  16. Fermi GRB 210105A: Global MASTER-Net observations report
  17. GW170817: HST observations at 3.4 years from merger
  18. GRB 210104A: early ATLAS detections of the bright afterglow
  19. GRB 210105A: Fermi GBM Final Real-time Localization
  20. GRB 210104A: Swift-XRT refined Analysis
  21. GRB 210104B: Swift/UVOT Upper Limits
  22. Konus-Wind detection of GRB 210104A
  23. GRB 210104A: 1.3m DFOT Optical Afterglow Detection
  24. GRB 210104B: Swift-XRT refined Analysis
  25. GRB 210104B: Assy optical upper limit
  26. GRB 210104A: DOAO optical afterglow observations
  27. GRB 210104B: Enhanced Swift-XRT position
  28. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  29. GRB 210104A: Swift-BAT refined analysis
  30. GRB 210104B: Nanshan/NEXT optical upper limit
  31. GRB 210104B: BOOTES network optical upper limit
  32. GRB 210104A: MASTER OT rebrightening detection
  33. GRB 210104A: Swift/UVOT Detection
  34. GRB 210104A: Fermi GBM detection
  35. GRB 210104A: Enhanced Swift-XRT position
  36. GRB 210102B: Tiled Swift observations
  37. GRB 210104B: Swift detection of a burst
  38. Swift GRB210104.88: Global MASTER-Net observations report
  39. GRB 210104A: MITSuME Ishigaki optical observation
  40. GRB 210102B: Assy optical observations
  41. Fermi GRB 210104A: Global MASTER-Net observations report
  42. GRB 210104A: Assy optical observations
  43. GRB 210104A: MITSuME Akeno optical observation
  44. GRB 210104A: BOOTES-4/MET early optical afterglow detection
  45. GRB 210104A: GWAC-F60A optical afterglow observations
  46. GRB 210104A: BALROG localization (Fermi Trigger 631452424 / GRB 210104477)
  47. GRB 210104A: Swift detection of a burst with a bright optical counterpart
  48. GRB 210104A: Fermi GBM Final Real-time Localization
  49. GRB 210102C: Swift-BAT refined analysis
  50. GRB 210102B: Swift-XRT observations
  51. Fermi GRB 210102C: Global MASTER-Net observations report
  52. GRB 210102C: Fermi GBM detection
  53. Swift GRB 210102C: Global MASTER-Net observations report
  54. GRB 210102C: Swift detection of a burst
  55. MAXI GRB210102.38: Global MASTER-Net observations report
  56. GRB 210102B: Tiled Swift observations
  57. GRB 210102B: MAXI/GSC detection
  58. Fermi GRB 210101A: Global MASTER-Net observations report
  59. INTEGRAL Weak #8913: AROMA-N Optical Observation
  60. Swift Trigger 1015615 is not a GRB
  61. Swift GRB210102.01: Global MASTER-Net observations report
  62. Fermi trigger No 631226368: Global MASTER-Net observations report
  63. Fermi trigger No 631119348: Global MASTER-Net observations report
  64. GRB 210101A: BALROG localization (Fermi Trigger 631205591 / GRB 210101620)
  65. GRB 210101A: Fermi GBM Final Real-time Localization
  66. Fermi trigger No 631113166: Global MASTER-Net observations report
  67. GRB 201229A: Swift/UVOT Detection
  68. Fermi trigger No 631118376: Global MASTER-Net observations report
  69. Fermi trigger No 631104264: Global MASTER-Net observations report
  70. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  71. Baksan Neutrino Observatory Alert 201230.40: Global MASTER-Net observations report
  72. GRB 201227A: Chilescope optical observations, possible optical counterpart
  73. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  74. GRB 201227A: Fermi GBM observation
  75. GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
  76. GRB 201229A: SAO RAS optical observations
  77. GRB 201229A: Nanshan/NEXT optical upper limit
  78. GRB 201227A: Swift-XRT observations
  79. GRB 201223A: SVOM-GWAC detected the optical counterpart during prompt emission phase
  80. GRB 201229A: Swift-XRT refined Analysis
  81. GRB 201229A: Swift-BAT refined analysis
  82. GRB 201104B: Maidanak and CrAO optical observations
  83. Fermi GRB 201229B: Global MASTER-Net observations report
  84. Konus-Wind observation of GRB 201227A
  85. GRB 201229B: BALROG localization (Fermi Trigger 630948017 / GRB 201229639)
  86. GRB 201229B: Fermi GBM Final Real-time Localization
  87. GRB 201229A: Enhanced Swift-XRT position
  88. GRB 201229A: Swift detection of a burst with a possible optical counterpart
  89. GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
  90. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  91. Fermi GRB 201228B: Global MASTER-Net observations report
  92. GRB 201228B: Fermi GBM Final Real-time Localization
  93. GRB 201227A: Insight-HXMT/HE detection
  94. GRB 201226A: Insight-HXMT/HE detection
  95. GRB 201227A: Tiled Swift observations
  96. GRB 201227A: Swift ToO observations
  97. GRB 201228A: Fermi GBM Final Real-time Localization
  98. IPN triangulation of GRB 201227A (short)
  99. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  100. GRB 201223A: AROMA-N Optical Observation

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