Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
New! BOOM Notices and Schema v7.0.0. 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 201009A: AstroSat CZTI detection
  2. GRB 201009A: AGILE detection of a burst
  3. GRB 201008A: Swift-XRT observations
  4. IceCube-200926A: Upper limits from Insight-HXMT Observations
  5. GRB 201008A: Swift ToO observations
  6. IceCube-201007A: Upper limits from Fermi-GBM Observations
  7. GRB 201008A: Swift/BAT-GUANO detection and possible arcminute localization
  8. Fermi-LAT Gamma-ray Observations of IceCube-201007A
  9. Fermi trigger No 623846261: Global MASTER-Net observations report
  10. Fermi trigger No 623873165: Global MASTER-Net observations report
  11. Swift-XRT observations of IceCube 201007A
  12. Baksan Neutrino Observatory Alert 201008.47: Global MASTER-Net observations report
  13. GRB 201008A: BALROG localization (Fermi Trigger 623846261 / GRB 201008443)
  14. IceCube-201007A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  15. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  16. IceCube Alert 201007.92: Global MASTER-Net observations report
  17. GRB 201006A: GROWTH-India Telescope optical upper limit
  18. GRB 201006A: Lowell Discovery Telescope upper limits
  19. GRB 201006A: MITSuME Akeno optical upper limits
  20. Fermi GRB 201007A: Global MASTER-Net observations report
  21. GRB 201007A: Fermi GBM Final Real-time Localization
  22. GRB 201006A: Swift-XRT refined Analysis
  23. GRB 201006A: Swift-BAT refined analysis
  24. Baksan Neutrino Observatory Alert 201006.88: Global MASTER-Net observations report
  25. GRB 201006A: Swift/UVOT Upper Limits
  26. GRB 201006A: Fermi GBM detection
  27. GRB 201006A is likely a short burst
  28. GRB 201006A: Enhanced Swift-XRT position
  29. INTEGRAL sub-threshold detection of GRB 201006A
  30. GRB 201006A: Swift detection of a burst
  31. Swift GRB201006.05: Global MASTER-Net observations report
  32. Fermi trigger No 623470566: Global MASTER-Net observations report
  33. GRB 201004A: Fermi GBM Final Localization
  34. Fermi trigger No 623493962: Global MASTER-Net observations report
  35. GRB 201001A: Swift/UVOT Upper Limits
  36. IceCube-200926A: No usable INTEGRAL data
  37. IceCube-200926B: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  38. IceCube-200929A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  39. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  40. GRB 201001A: TSHAO optical upper limit
  41. GRB 201001A: Xinglong-2.16m optical upper limit
  42. GRB 201001A: MITSuME Akeno optical upper limits
  43. IceCube-200926A: JCMT/SCUBA2 observations
  44. IceCube-200929A: No significant detection in HAWC
  45. GRB 201001A: Swift-BAT refined analysis
  46. GRB 201001A: Swift-XRT refined Analysis
  47. IceCube-200929A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 201001A: Fermi GBM observation
  49. Swift-XRT observations of IceCube 200929A
  50. GRB 201001A: Enhanced Swift-XRT position
  51. GRB 201001A: Swift detection of a burst
  52. GRB 201001A: Fermi GBM Final Real-time Localization
  53. Fermi-LAT Gamma-ray Observations of IceCube-200929A
  54. IceCube-200929A: Upper limits from Fermi-GBM Observations
  55. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  56. IceCube-200926B: No significant detection in HAWC
  57. GRB 200928B: Insight-HXMT/HE detection
  58. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  59. IceCube-200926B: Upper limits from Fermi-GBM Observations
  60. IceCube-200926A: Upper limits from Fermi-GBM Observations
  61. IceCube Alert 200929.74: Global MASTER-Net observations report
  62. IceCube-200926A: No significant detection in HAWC
  63. Fermi GRB 200929A: Global MASTER-Net observations report
  64. GRB 200928B: AstroSat CZTI detection
  65. GRB 200929A: Fermi GBM Final Real-time Localization
  66. IceCube-200926B: Upper limits from a search for additional neutrino events in IceCube
  67. IceCube-200926A: Upper limits from a search for additional neutrino events in IceCube
  68. GRB 200928B: BALROG localization (Fermi Trigger 622991684 / GRB 200928552)
  69. GRB 200928B: Fermi GBM Final Real-time Localization
  70. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  71. Fermi-LAT Gamma-ray Observations of IceCube-200926B
  72. GRB 200928A: Fermi GBM Final Localization
  73. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  74. IceCube Alert 200926.94: Global MASTER-Net observations report
  75. Swift-XRT observations of IceCube 200926A
  76. Konus-Wind detection of GRB 200920B
  77. Fermi-LAT Gamma-ray Observations of IceCube-200926A
  78. GRB 200925B: Swift-XRT refined analysis update
  79. GRB 200925B NUTTelA-TAO / BSTI Early Measurements (Preliminary)
  80. IceCube Alert 200926.33: Global MASTER-Net observations report
  81. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  82. GRB 200925B: Swift-XRT refined Analysis
  83. GRB 200925B: Swift/UVOT Detection
  84. GRB 200925B: Swift-BAT refined analysis
  85. GRB 200922A: Chilescope optical observations
  86. IceCube-200926A: IceCube observation of a high-energy neutrino candidate event
  87. GRB 200925B: Enhanced Swift-XRT position
  88. Swift GRB 200925B: Global MASTER-Net OT detection
  89. GRB 200925B: OSN Afterglow Candidate Discovery
  90. GRB 200925B: Prompt enhanced Swift-XRT position
  91. GRB 200925B: Swift detection of a burst
  92. Swift GRB200925.91: Global MASTER-Net observations report
  93. Fermi GRB 200925A: Global MASTER-Net observations report
  94. GRB 200925A: Fermi GBM Final Real-time Localization
  95. Konus-Wind observation of GRB 200914A
  96. Fermi GRB 200924A: Global MASTER-Net observations report
  97. GRB 200924B: Fermi GBM Final Localization
  98. GRB 200922A: chance superposition between optical afterglow and archival star
  99. Fermi trigger No 622618714: Global MASTER-Net observations report
  100. GRB 200922A: Insight-HXMT/HE detection

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