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 201229A: Enhanced Swift-XRT position
  2. GRB 201229A: Swift detection of a burst with a possible optical counterpart
  3. GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
  4. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  5. Fermi GRB 201228B: Global MASTER-Net observations report
  6. GRB 201228B: Fermi GBM Final Real-time Localization
  7. GRB 201227A: Insight-HXMT/HE detection
  8. GRB 201226A: Insight-HXMT/HE detection
  9. GRB 201227A: Tiled Swift observations
  10. GRB 201227A: Swift ToO observations
  11. GRB 201228A: Fermi GBM Final Real-time Localization
  12. IPN triangulation of GRB 201227A (short)
  13. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  14. GRB 201223A: AROMA-N Optical Observation
  15. GRB 201227A: AGILE detection of a burst
  16. Fermi trigger No 630681391: Global MASTER-Net observations report
  17. GRB 201223A: Swift/UVOT Detection
  18. GRB 201223A: HCT optical upper limit
  19. Baksan Neutrino Observatory Alert 201225.54: Global MASTER-Net observations report
  20. GRB 201223A: AbAO optical observations
  21. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  22. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  23. GRB 201223A: Swift-XRT refined Analysis
  24. GRB 201223A: Enhanced Swift-XRT position
  25. GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
  26. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  27. GRB 201223A: Mondy and Kitab optical observations
  28. GRB 201223A: GWAC-F60A optical afterglow observations
  29. GRB 201223A: iTelescope optical afterglow observations
  30. GRB 201223A: MITSuME Akeno optical observation
  31. GRB 201223A: Swift-BAT refined analysis
  32. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  33. GRB 201223A: Fermi GBM Detection
  34. GRB 201223A: BOOTES-4/MET early optical observation
  35. GRB 201223A: Nanshan/NEXT early optical afterglow detection
  36. GRB 201223A: Swift detection of a burst with a bright optical counterpart
  37. Swift GRB201223.75: Global MASTER-Net OT detection
  38. Swift GRB201223.75: Global MASTER-Net observations report
  39. Swift-XRT observations of Icecube 201222A
  40. IceCube-201222A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-201221A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube-201222A: No significant detection in HAWC
  43. IceCube-201221A: No significant detection in HAWC
  44. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  45. GRB 201221A: REM early-time afterglow detection
  46. GRB 201221D: 3.6m DOT optical observations
  47. GRB 201221B: Insight-HXMT/HE detection
  48. IceCube-201221A: Upper limits from Insight-HXMT/HE observations
  49. Fermi trigger No 630389391: Global MASTER-Net observations report
  50. GRB 201221D: SMA submm observation
  51. Fermi GRB 201222B: Global MASTER-Net observations report
  52. GRB 201221D: MMT MMIRS detection of marginally extended source
  53. GRB 201221D: LCOGT upper limits
  54. GRB 201221D: Fermi GBM detection
  55. GRB 201221D: Swift-BAT refined analysis
  56. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  57. GRB 201216A - further Swift-XRT observations
  58. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  59. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  60. IceCube-201222A: not observable by Fermi-GBM
  61. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  62. Short GRB201221D: High Redshift from OSIRIS/GTC
  63. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  64. Konus-Wind detection of GRB 201221D (short)
  65. GRB 201221D: Swift/UVOT Upper Limits
  66. GRB 201221D: Lowell Discovery Telescope afterglow observations
  67. GRB 201222B: BALROG localization (Fermi Trigger / GRB 201222461)
  68. GRB 201222B: Fermi GBM Final Real-time Localization
  69. GRB 201221D: FRAM-ORM optical limit
  70. GRB 201221D: Swift-XRT refined Analysis
  71. IceCube Alert 201222.04: Global MASTER-Net observations report
  72. Swift GRB 201221D: Global MASTER-Net observations report
  73. Fermi GRB 201221E: Global MASTER-Net observations report
  74. IceCube-201222A: IceCube observation of a high-energy neutrino candidate event
  75. GRB 201221D: Enhanced Swift-XRT position
  76. GRB 201221D: Nanshan/NEXT early optical upper limit
  77. GRB 201221D: candidate optical counterpart from the NOT
  78. GRB 201221A: Swift-BAT refined analysis
  79. GRB 201222A: Fermi GBM Final Real-time Localization
  80. GRB 201221E: Fermi GBM Final Real-time Localization
  81. GRB 201221D: Prompt enhanced Swift-XRT position
  82. GRB 201221D: Swift detection of a bright short burst
  83. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  84. Fermi GBM Sub-Threshold Detection of GRB 201221A
  85. GRB 201221A: Swift/UVOT Upper Limits
  86. GRB 201221A: Swift-XRT refined Analysis
  87. GRB 201221C: MASTER optical observtion
  88. Swift Trigger 1014012: possible GRB 201221C
  89. GRB 201221A: Enhanced Swift-XRT position
  90. IceCube-201221A: not observable by Fermi-GBM
  91. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  92. IceCube-201221A: IceCube observation of a high-energy neutrino candidate event
  93. GRB 201221B: Fermi GBM Final Real-time Localization
  94. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  95. GRB 201221A: FRAM-Auger optical limit
  96. Swift GRB 201221A: Global MASTER-Net observations report
  97. GRB 201221A: Prompt enhanced Swift-XRT position
  98. GRB 201221A: Swift detection of a burst
  99. Konus-Wind observation of GRB 201218A
  100. GRB 201209A: Mondy optical observations, afterglow confirmation

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