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. IceCube-201209A: No neutrino counterpart candidates in ANTARES search
  2. IceCube Alert 201209.43: Global MASTER-Net observations report
  3. GRB 201209A: Swift-BAT refined analysis
  4. IPN triangulation of GRB 201207A
  5. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  6. GRB 201208A: Swift-XRT afterglow detection
  7. GRB 201208A: Fermi GBM observation
  8. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  9. GRB 201208A: LCO observations
  10. GRB 201209A: Swift-XRT refined Analysis
  11. GRB 201209A: Xinglong-2.16m likely optical afterglow detection
  12. IceCube-201209A: IceCube observation of a high-energy neutrino candidate event
  13. GRB 201209A: AstroSat CZTI detection
  14. GRB 201207A: AGILE detection
  15. GRB 201209A: Enhanced Swift-XRT position
  16. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  17. GRB 201209A: KAIT Optical Upper Limit
  18. GRB 201209A: FRAM-Auger optical limit
  19. GRB 201209A: Swift detection of a burst
  20. Swift GRB201209.24: Global MASTER-Net observations report
  21. GRB 201208A: Fermi-LAT detection
  22. GRB 201208A: Swift ToO observations
  23. GRB 201208A: AstroSat CZTI detection
  24. GRB 201207A: AstroSat CZTI detection
  25. Fermi GRB 201208A: Global MASTER-Net observations report
  26. GRB 201208A: Fermi GBM Final Real-time Localization
  27. Fermi GRB 201207A: Global MASTER-Net observations report
  28. GRB 201207A: Fermi GBM Final Real-time Localization
  29. GRB 201203A: Swift-BAT refined analysis
  30. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  31. GRB 201203A: GROWTH-India Telescope optical upper limit.
  32. GRB 201203A: MITSuME Okayama optical upper limits
  33. Swift GRB 201203A: Global MASTER-Net observations report
  34. GRB 201203A: Swift-XRT afterglow detection
  35. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  36. GRB 201203A: KAIT Optical Upper Limit
  37. GRB 201203A: DDOTI Observations
  38. GRB 201203A: FRAM-Auger optical limit
  39. GRB 201203A: Swift detection of a burst
  40. IceCube-201130A: No significant detection in HAWC
  41. IceCube-201130A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  43. GRB201130A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 628407054)
  44. GRB 201128B: Swift-XRT observations
  45. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  46. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  47. IceCube-201130A: Not observable by Fermi-GBM
  48. GRB 201201A: DDOTI Observations
  49. Fermi GRB 201201A: Global MASTER-Net observations report
  50. GRB 201128B: Swift ToO observations
  51. Swift-XRT observations of IceCube 201130A
  52. GRB 201201A: Fermi GBM Final Real-time Localization
  53. GRB 201128B: Swift/BAT-GUANO detection and arcminute localization
  54. GRB 201128A: Swift/UVOT Upper Limits
  55. IceCube-201130A: IceCube observation of a high-energy neutrino candidate event
  56. IceCube Alert 201130.85: Global MASTER-Net observations report
  57. GRB 201130A: DDOTI Observations
  58. Fermi GRB 201130A: Global MASTER-Net observations report
  59. GRB 201130A: Fermi GBM Final Real-time Localization
  60. Baksan Neutrino Observatory Alert 201128.90: Global MASTER-Net observations report
  61. GRB 201128A: Swift-BAT refined analysis
  62. GRB 201128A: Swift-XRT refined Analysis
  63. Fermi trigger No 628278856: Global MASTER-Net observations report
  64. GRB 201128A: Enhanced Swift-XRT position
  65. GRB 201128A: DDOTI Observations
  66. GRB 201128A: Swift detection of a burst
  67. Fermi trigger No 628140709: DDOTI/OAN optical observations report
  68. Fermi trigger No 628140709: Global MASTER-Net observations report
  69. IceCube-201114A: Updated photometry for three DECam candidate optical counterparts
  70. GRB 201121A: Insight-HXMT/HE detection
  71. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  72. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  73. IceCube Alert 201124.34: Global MASTER-Net observations report
  74. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-201124A
  75. GRB 200826A: TNG and LBT constraints on a supernova bump
  76. GRB 201122A: Insight-HXMT/HE detection
  77. IceCube-201114A: DECam observations and candidate optical counterpart
  78. IceCube-201120A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 201015A L-band observations with e-MERLIN
  80. INTEGRAL Weak #8831 and #8832: AROMA-N Optical Observation
  81. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  82. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  83. Fermi trigger No 627645769: Global MASTER-Net observations report
  84. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  85. GRB 201015A radio afterglow with e-MERLIN
  86. Fermi GRB 201121A: Global MASTER-Net observations report
  87. GRB 201121B: Fermi GBM Final Real-time Localization
  88. GRB 201121A: BALROG localization (Fermi Trigger 627614994 / GRB 201121062)
  89. GRB 201121A: Fermi GBM Final Real-time Localization
  90. Fermi GRB 201120B: Global MASTER-Net observations report
  91. GRB 201120B: Fermi GBM Final Localization
  92. GRB 201120A: Fermi GBM Final Localization
  93. IceCube-201120A: Upper limits from Fermi-GBM Observations
  94. Fermi trigger No 627557935: Global MASTER-Net observations report
  95. Baksan Neutrino Observatory Alert 201120.43: Global MASTER-Net observations report
  96. IceCube Alert 201120.41: Global MASTER-Net observations report
  97. IceCube-201120A: IceCube observation of a high-energy neutrino candidate event
  98. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  99. ZTF20acozryr/AT2020yxz (GRB 201103B): correction to the GCN #28883 CrAO/ZTSh optical observations
  100. IceCube 201114A: Swift followup of Fermi J0703.5+0505

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