Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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 200521A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 200521A: AGILE/MCAL and ratemeters detection
  3. GRB 200517A: Swift-XRT Confirmation of afterglow
  4. GRB 200514B: Fermi GBM observation
  5. GRB 200519A: CALET Gamma-Ray Burst Monitor detection
  6. GRB 200519A: R-band follow-up from HCT
  7. GRB 200519A: Swift-BAT refined analysis
  8. GRB 200519A: Insight-HXMT/HE detection
  9. GRB 200519A: Swift/UVOT Detection
  10. Fermi trigger No 611676654: Global MASTER-Net observations report
  11. GRB 200519A: GROWTH-India optical follow-up
  12. GRB 200519A: AstroSat CZTI detection
  13. Swift GRB 200519A: Global MASTER-Net observations report
  14. GRB 200519A: 1.3m DFOT Optical Afterglow Detection
  15. GRB 200519A: Swift-XRT refined Analysis
  16. Fermi trigger No 611605955: Global MASTER-Net observations report
  17. GRB 200519A: Enhanced Swift-XRT position
  18. GRB 200519A: BOOTES-3/YA optical counterpart observations
  19. GRB 200519A: LCO Optical Afterglow Detection
  20. Fermi GBM Sub-Threshold Detection of GRB 200517A
  21. GRB 200519A: iTelescope optical afterglow detection
  22. GRB 200519A: Swift detection of a burst with an optical afterglow
  23. IPN triangulation of GRB 200514B (short)
  24. GRB 200517A: Swift-XRT afterglow detection
  25. GRB 200514A: AstroSat CZTI detection
  26. Fermi trigger No 611434353: Global MASTER-Net observations report
  27. GRB 200517A: Tiled Swift observations
  28. GRB 200517A: MAXI/GSC detection
  29. Swift J1818.0-1607: BOOTES-3/YA optical upper limit
  30. GRB 200514B: BALROG localization (Fermi Trigger 611140062 / GRB 200514380)
  31. Swift GRB200516.63: Global MASTER-Net observations report
  32. Swift Detection of a burst from SGR Swift J1818.0-1607
  33. GRB 200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062) - More Candidates
  34. GRB 200514A: MITSuME Akeno optical upper limits
  35. GRB 200514A: CALET Gamma-Ray Burst Monitor detection
  36. GRB 200512A: Swift-BAT refined analysis
  37. GRB200514B: YSE detection of ZTF20aazpphd
  38. Optical transient ZTF20aazpphd is unrelated to GRB 200514B
  39. GRB 200514B: GROWTH-India follow-up of ZTF20aazpphd (AT2020jww)
  40. GRB200514B: ATLAS detections of ZTF20aazpphd
  41. GRB200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062)
  42. GRB 200514B: Fermi GBM Final Real-time Localization
  43. GRB 200514A: MAXI/GSC detection
  44. Baksan Neutrino Observatory Alert 200512.: Global MASTER-Net observations report
  45. GRB 200512A: LCO Optical Upper Limits
  46. IceCube-200512A: Upper limits from a search for additional neutrino events in IceCube
  47. Fermi GBM Sub-Threshold Detection of GRB 200512A
  48. GRB 200512A: Swift/UVOT Upper Limits
  49. GRB 200512A: Swift-XRT refined Analysis
  50. GRB 200512A: Enhanced Swift-XRT position
  51. AGILE detection of a burst from SGR 1935+2154 on May 10, 2020
  52. GRB 200512A: Swift detection of a burst
  53. Fermi-LAT Gamma-ray Observations of IceCube-200512A
  54. SGR 1935+2154: AstroSat CZTI detection
  55. IceCube-200512A: not observable by Fermi-GBM
  56. IceCube Alert 200512.31: Global MASTER-Net observations report
  57. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  58. IceCube-200512A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  59. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  60. Insight-HXMT's continued observation plan for SGR J1935+2154
  61. Baksan Neutrino Observatory Alert 200511.76: Global MASTER-Net observations report
  62. GRB 200510A: AstroSat CZTI detection
  63. Konus-Wind observation of SGR 1935+2154 activity on 2020 May 10
  64. IPN triangulation of a bright burst from SGR 1935+2154 on 2020-05-10 at 06:12 UT
  65. GRB 200509A: Swift-BAT refined analysis
  66. GRB 200510A: BALROG localization (Fermi Trigger 610800081 / GRB 200510445)
  67. GRB 200510A: Fermi GBM Final Real-time Localization
  68. GRB 200509A: GROWTH-India r band upper limits
  69. GRB 200509A: Swift/UVOT Detection
  70. GRB 200509C: Fermi GBM Final Real-time Localization
  71. GRB 200509B: Fermi GBM Final Real-time Localization
  72. Swift GRB 200509A: Global MASTER-Net observations report
  73. GRB 200509A: LCO Optical Afterglow Detection
  74. GRB 200509A: Swift-XRT refined Analysis
  75. GRB 200509A: Enhanced Swift-XRT position
  76. GRB 200509A: Zadko observatory - Gingin optical upper limits
  77. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  78. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  79. GRB 200507A: Fermi GBM Final Real-time Localization
  80. GRB 200506A: AstroSat CZTI detection
  81. GRB 200506C: AstroSat CZTI detection
  82. Swift Detection of a burst from SGR Swift J1818.0-1607
  83. Swift GRB200506.73: Global MASTER-Net observations report
  84. GRB 200422A: INTEGRAL observations
  85. GRB 200505A: AGILE detection
  86. GRB 200506C: Fermi GBM Final Real-time Localization
  87. GRB 200506B: Fermi GBM Final Real-time Localization
  88. GRB 200506A: Fermi GBM Final Real-time Localization
  89. GRB 200505A: Fermi GBM Final Real-time Localization
  90. Insight-HXMT detection of a short bright burst from SGR 1935+2154
  91. AGILE detection of a short and hard X-ray burst possibly related to SGR 1935+2154
  92. GRB 200502A: AstroSat CZTI detection
  93. GRB 200503A: AGILE observations
  94. GRB 200502A: AGILE observations
  95. GRB 200503B: BALROG localization (Fermi Trigger 610219118 / GRB 200503721)
  96. GRB 200503B: Fermi GBM Final Real-time Localization
  97. Geocentric time correction for Insight-HXMT detection of the x-ray counterpart of the FRB by CHIME and STARE2 from SGR 1935+2154
  98. AstroSat CZTI detection : GRB200503A
  99. Insight-HXMT X-ray and hard X-ray upper limits to the radio burst detected by FAST from SGR 1935+2154
  100. No optical bursts detected from SGR J1935+2154 by 24 fps observations with Tomo-e Gozen

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