Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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 200925B: Swift/UVOT Detection
  2. GRB 200925B: Swift-BAT refined analysis
  3. GRB 200922A: Chilescope optical observations
  4. IceCube-200926A: IceCube observation of a high-energy neutrino candidate event
  5. GRB 200925B: Enhanced Swift-XRT position
  6. Swift GRB 200925B: Global MASTER-Net OT detection
  7. GRB 200925B: OSN Afterglow Candidate Discovery
  8. GRB 200925B: Prompt enhanced Swift-XRT position
  9. GRB 200925B: Swift detection of a burst
  10. Swift GRB200925.91: Global MASTER-Net observations report
  11. Fermi GRB 200925A: Global MASTER-Net observations report
  12. GRB 200925A: Fermi GBM Final Real-time Localization
  13. Konus-Wind observation of GRB 200914A
  14. Fermi GRB 200924A: Global MASTER-Net observations report
  15. GRB 200924B: Fermi GBM Final Localization
  16. GRB 200922A: chance superposition between optical afterglow and archival star
  17. Fermi trigger No 622618714: Global MASTER-Net observations report
  18. GRB 200922A: Insight-HXMT/HE detection
  19. GRB 200924A: Fermi GBM Final Real-time Localization
  20. Fermi GRB 200923A: Global MASTER-Net observations report
  21. IceCube Alert 200921.80: Global MASTER-Net observations report
  22. GRB 200923A: Fermi GBM Final Real-time Localization
  23. IceCube-200921A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 200922A: Swift-BAT refined analysis
  25. Improved enhanced Swift-XRT position of GRB 200922A
  26. GRB 200922A: Swift/UVOT Detection
  27. Fermi-LAT Gamma-ray Observations of IceCube-200921A and detection of a new gamma-ray source, Fermi J1256.9+2630
  28. IceCube-200921A: no significant detection in HAWC observations
  29. Fermi GRB 200922B: Global MASTER-Net observations report
  30. GRB 200922A: LCO observations
  31. Swift GRB 200922A: Global MASTER-Net observations report
  32. GRB 200922A: Swift-XRT refined Analysis
  33. GRB 200917A: Swift/UVOT Upper Limits
  34. GRB 200922B: Fermi GBM Final Real-time Localization
  35. GRB 200922A: Enhanced Swift-XRT position
  36. GRB 200919C: Insight-HXMT/HE detection
  37. GRB 200922A: Swift detection of a burst with possible optical counterpart
  38. IceCube-200921A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  39. IceCube-200921A: Upper limits from Fermi-GBM Observations
  40. IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
  41. IPN triangulation of GRB 200920B (short)
  42. GRB 200914A: Swift-XRT further observations
  43. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  44. GRB 200920B: AGILE/MCAL detection of a burst
  45. GRB 200920A: Fermi GBM Final Real-time Localization
  46. Fermi GRB 200919C: Global MASTER-Net observations report
  47. GRB 200919C: Fermi GBM Final Real-time Localization
  48. GRB 200919A: CrAO/ZTSh early optical upper limit
  49. Fermi GRB 200919B: Global MASTER-Net observations report
  50. GRB 200919A: Swift-BAT refined analysis
  51. GRB 200919B: Fermi GBM Final Real-time Localization
  52. GRB 200916B: MASTER optical observation
  53. Swift GRB200919.08: Global MASTER-Net observations report
  54. GRB 200919A: Swift detection of a burst
  55. IceCube-200916A: AbAO observations of optical candidates ZTF20acaapwk/AT2020tno, ZTF20acaapwo/AT2020tnp
  56. IceCube-200916A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 200916B: AstroSat CZTI detection
  58. GRB 200917A: GROWTH-India Telescope optical upper limit.
  59. Swift-XRT observations of IceCube 200916A
  60. IceCube-200916A: No significant detection in HAWC
  61. GRB 200917A: Swift-BAT refined analysis
  62. IceCube-200916A: No neutrino counterpart candidates in ANTARES search
  63. Fermi-GBM Sub-Threshold Detection of GRB 200917A
  64. GRB 200917A: Swift-XRT refined Analysis
  65. IceCube-200916A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  66. Swift GRB 200917A: Global MASTER-Net observations report
  67. IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
  68. IPN triangulation of GRB 200916B (short)
  69. IceCube-200916A: Upper limits from Fermi-GBM Observations
  70. Fermi-LAT Gamma-ray Observations of IceCube-200916A
  71. IceCube Alert 200916.86: Global MASTER-Net observations report
  72. GRB 200917A: Enhanced Swift-XRT position
  73. GRB 200917A: Swift detection of a burst
  74. Swift-XRT observations of IceCube 200911A
  75. IceCube-200916A - IceCube observation of a high-energy neutrino candidate track-like event
  76. Fermi GRB 200916A: Global MASTER-Net observations report
  77. GRB 200916A: Fermi GBM Final Real-time Localization
  78. Fermi trigger No 621893860: Global MASTER-Net observations report
  79. Fermi trigger No 621833240: Global MASTER-Net observations report
  80. Integral GRB200914.53: Global MASTER-Net observations report
  81. Fermi GRB 200914A: Global MASTER-Net observations report
  82. GRB 200914A: AGILE detection
  83. GRB 200914A: Swift-XRT observations
  84. GRB 200914A: Fermi GBM observation
  85. IceCube Alert 200914.00: Global MASTER-Net observations report
  86. IceCube-200911A: No significant detection in HAWC
  87. Fermi-LAT Gamma-ray Observations of IceCube-200911A and detection of a new gamma-ray source, Fermi J0330.1+3743
  88. GRB 200914A: Swift ToO observations
  89. GRB 200914A : A long GRB detected by INTEGRAL
  90. GRB 200914A: BALROG localization (Fermi Trigger 621780515 / GRB 200914534)
  91. GRB 200914A: Fermi GBM Final Real-time Localization
  92. IceCube-200911A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-200911A: No neutrino counterpart candidates in ANTARES search
  94. IceCube Alert 200911.60: Global MASTER-Net observations report
  95. IceCube-200911A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  96. IceCube-200911A: not observable by Fermi-GBM
  97. IceCube-200911A: IceCube observation of a high-energy neutrino candidate event
  98. GRB 200826A: uGMRT radio upper limit at 1.25 GHz
  99. IPN triangulation of GRB 200907A (short)
  100. GRB 200909B: Swift-BAT refined analysis

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