Skip to main content
Retirement of GCN Classic VOEvent Brokers. 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 201227A: Tiled Swift observations
  2. GRB 201227A: Swift ToO observations
  3. GRB 201228A: Fermi GBM Final Real-time Localization
  4. IPN triangulation of GRB 201227A (short)
  5. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  6. GRB 201223A: AROMA-N Optical Observation
  7. GRB 201227A: AGILE detection of a burst
  8. Fermi trigger No 630681391: Global MASTER-Net observations report
  9. GRB 201223A: Swift/UVOT Detection
  10. GRB 201223A: HCT optical upper limit
  11. Baksan Neutrino Observatory Alert 201225.54: Global MASTER-Net observations report
  12. GRB 201223A: AbAO optical observations
  13. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  14. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  15. GRB 201223A: Swift-XRT refined Analysis
  16. GRB 201223A: Enhanced Swift-XRT position
  17. GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
  18. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  19. GRB 201223A: Mondy and Kitab optical observations
  20. GRB 201223A: GWAC-F60A optical afterglow observations
  21. GRB 201223A: iTelescope optical afterglow observations
  22. GRB 201223A: MITSuME Akeno optical observation
  23. GRB 201223A: Swift-BAT refined analysis
  24. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  25. GRB 201223A: Fermi GBM Detection
  26. GRB 201223A: BOOTES-4/MET early optical observation
  27. GRB 201223A: Nanshan/NEXT early optical afterglow detection
  28. GRB 201223A: Swift detection of a burst with a bright optical counterpart
  29. Swift GRB201223.75: Global MASTER-Net OT detection
  30. Swift GRB201223.75: Global MASTER-Net observations report
  31. Swift-XRT observations of Icecube 201222A
  32. IceCube-201222A: Upper limits from a search for additional neutrino events in IceCube
  33. IceCube-201221A: Upper limits from a search for additional neutrino events in IceCube
  34. IceCube-201222A: No significant detection in HAWC
  35. IceCube-201221A: No significant detection in HAWC
  36. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  37. GRB 201221A: REM early-time afterglow detection
  38. GRB 201221D: 3.6m DOT optical observations
  39. GRB 201221B: Insight-HXMT/HE detection
  40. IceCube-201221A: Upper limits from Insight-HXMT/HE observations
  41. Fermi trigger No 630389391: Global MASTER-Net observations report
  42. GRB 201221D: SMA submm observation
  43. Fermi GRB 201222B: Global MASTER-Net observations report
  44. GRB 201221D: MMT MMIRS detection of marginally extended source
  45. GRB 201221D: LCOGT upper limits
  46. GRB 201221D: Fermi GBM detection
  47. GRB 201221D: Swift-BAT refined analysis
  48. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  49. GRB 201216A - further Swift-XRT observations
  50. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  51. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  52. IceCube-201222A: not observable by Fermi-GBM
  53. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  54. Short GRB201221D: High Redshift from OSIRIS/GTC
  55. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  56. Konus-Wind detection of GRB 201221D (short)
  57. GRB 201221D: Swift/UVOT Upper Limits
  58. GRB 201221D: Lowell Discovery Telescope afterglow observations
  59. GRB 201222B: BALROG localization (Fermi Trigger / GRB 201222461)
  60. GRB 201222B: Fermi GBM Final Real-time Localization
  61. GRB 201221D: FRAM-ORM optical limit
  62. GRB 201221D: Swift-XRT refined Analysis
  63. IceCube Alert 201222.04: Global MASTER-Net observations report
  64. Swift GRB 201221D: Global MASTER-Net observations report
  65. Fermi GRB 201221E: Global MASTER-Net observations report
  66. IceCube-201222A: IceCube observation of a high-energy neutrino candidate event
  67. GRB 201221D: Enhanced Swift-XRT position
  68. GRB 201221D: Nanshan/NEXT early optical upper limit
  69. GRB 201221D: candidate optical counterpart from the NOT
  70. GRB 201221A: Swift-BAT refined analysis
  71. GRB 201222A: Fermi GBM Final Real-time Localization
  72. GRB 201221E: Fermi GBM Final Real-time Localization
  73. GRB 201221D: Prompt enhanced Swift-XRT position
  74. GRB 201221D: Swift detection of a bright short burst
  75. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  76. Fermi GBM Sub-Threshold Detection of GRB 201221A
  77. GRB 201221A: Swift/UVOT Upper Limits
  78. GRB 201221A: Swift-XRT refined Analysis
  79. GRB 201221C: MASTER optical observtion
  80. Swift Trigger 1014012: possible GRB 201221C
  81. GRB 201221A: Enhanced Swift-XRT position
  82. IceCube-201221A: not observable by Fermi-GBM
  83. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  84. IceCube-201221A: IceCube observation of a high-energy neutrino candidate event
  85. GRB 201221B: Fermi GBM Final Real-time Localization
  86. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  87. GRB 201221A: FRAM-Auger optical limit
  88. Swift GRB 201221A: Global MASTER-Net observations report
  89. GRB 201221A: Prompt enhanced Swift-XRT position
  90. GRB 201221A: Swift detection of a burst
  91. Konus-Wind observation of GRB 201218A
  92. GRB 201209A: Mondy optical observations, afterglow confirmation
  93. GRB 201214A: TSHAO optical upper limit
  94. GRB 201214A: Swift-XRT afterglow detection
  95. GRB 201214A: 1.3m DFOT, optical upper limits
  96. IPN triangulation of GRB 201218A
  97. Fermi GRB 201218B: Global MASTER-Net observations report
  98. GRB 201218B: Fermi GBM Final Real-time Localization
  99. Fermi GRB 201218A: Global MASTER-Net observations report
  100. GRB201216C: No significant detection in HAWC

Advanced

Download all Circulars as a .tar.gz archive:
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