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"

28095 results found.

  1. GRB 201221A: Swift-XRT refined Analysis
  2. Swift Trigger 1014012: possible GRB 201221C
  3. GRB 201221A: Enhanced Swift-XRT position
  4. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  5. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  6. GRB 201221A: Swift detection of a burst
  7. GRB 201209A: Mondy optical observations, afterglow confirmation
  8. GRB 201214A: TSHAO optical upper limit
  9. GRB 201214A: Swift-XRT afterglow detection
  10. GRB 201214A: 1.3m DFOT, optical upper limits
  11. IPN triangulation of GRB 201218A
  12. GRB201216C: No significant detection in HAWC
  13. GRB 201216C: Liverpool Telescope First Hour Observations
  14. GRB 201218A: BALROG localization (Fermi Trigger 629957660 / GRB 201218177)
  15. IceCube-201209A : MAXI/GSC upper limit
  16. GRB 201216C: Swift-BAT refined analysis
  17. GRB 201216C: Fermi-LAT upper limit
  18. GRB 201216C: Fermi GBM detection
  19. GRB 201216A: Fermi GBM detection
  20. GRB 201216C: Swift/UVOT Upper Limits
  21. GRB 201216A: Swift-XRT observations
  22. GRB 201216C: Enhanced Swift-XRT position
  23. GRB 201216C: VLT afterglow candidate discovery
  24. GRB 201216C: Swift-XRT observations
  25. GRB 201216A: Swift/BAT-GUANO detection and arcminute localization
  26. GRB 201214B: MITSuME Akeno optical upper limits
  27. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  28. GRB 201214B: Lowell Discovery Telescope optical observations
  29. GRB 201214B: Swift-XRT observations
  30. GRB 201209A: Insight-HXMT/HE detection
  31. IceCube-201209A: Upper limits from Insight-HXMT/HE observations
  32. GRB 201214A: Swift-XRT observations
  33. GRB 201215A: BALROG localization (Fermi Trigger 629706213 / GRB 201215266)
  34. IceCube-201209: No significant detection in HAWC
  35. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  36. Long-lasting X-ray emission from GW170817 detected by Chandra
  37. GRB 201214A: A long GRB detected by INTEGRAL
  38. Integral GRB201214.26: Global MASTER-Net observations report
  39. GRB 201015A: optical observations and supernova identification
  40. GRB 201203A: Zeiss-1000 (Koshka observatory) optical upper limit
  41. GRB 201203A: 1.3m DFOT, optical upper limits
  42. GRB 200826A: GMOS-N detected source magnitude (Correction)
  43. GRB 201015A: 5-GHz radio afterglow detection with the EVN
  44. GRB 201209A: Swift/UVOT Upper Limits
  45. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  46. IceCube-201209A: No neutrino counterpart candidates in ANTARES search
  47. GRB 201209A: Swift-BAT refined analysis
  48. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  49. GRB 201208A: Swift-XRT afterglow detection
  50. GRB 201208A: Fermi GBM observation
  51. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  52. GRB 201208A: LCO observations
  53. GRB 201209A: Swift-XRT refined Analysis
  54. GRB 201209A: Xinglong-2.16m likely optical afterglow detection
  55. GRB 201209A: Enhanced Swift-XRT position
  56. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  57. GRB 201209A: Swift detection of a burst
  58. GRB 201207A: AstroSat CZTI detection
  59. GRB 201203A: Swift-BAT refined analysis
  60. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  61. GRB 201203A: GROWTH-India Telescope optical upper limit.
  62. GRB 201203A: MITSuME Okayama optical upper limits
  63. GRB 201203A: Swift-XRT afterglow detection
  64. GRB 201203A: DDOTI Observations
  65. GRB 201203A: Swift detection of a burst
  66. IceCube-201130A: No significant detection in HAWC
  67. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  68. GRB 201128B: Swift-XRT observations
  69. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  70. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  71. GRB 201201A: DDOTI Observations
  72. Swift-XRT observations of IceCube 201130A
  73. GRB 201201A: Fermi GBM Final Real-time Localization
  74. GRB 201128B: Swift/BAT-GUANO detection and arcminute localization
  75. GRB 201128A: Swift/UVOT Upper Limits
  76. GRB 201130A: DDOTI Observations
  77. Baksan Neutrino Observatory Alert 201128.90: Global MASTER-Net observations report
  78. GRB 201128A: Swift-BAT refined analysis
  79. GRB 201128A: Swift-XRT refined Analysis
  80. GRB 201128A: Enhanced Swift-XRT position
  81. GRB 201128A: DDOTI Observations
  82. GRB 201128A: Swift detection of a burst
  83. Fermi trigger No 628140709: DDOTI/OAN optical observations report
  84. GRB 201121A: Insight-HXMT/HE detection
  85. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  86. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  87. GRB 200826A: TNG and LBT constraints on a supernova bump
  88. GRB 201122A: Insight-HXMT/HE detection
  89. IceCube-201114A: DECam observations and candidate optical counterpart
  90. IceCube-201120A: Upper limits from a search for additional neutrino events in IceCube
  91. GRB 201015A L-band observations with e-MERLIN
  92. INTEGRAL Weak #8831 and #8832: AROMA-N Optical Observation
  93. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  94. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  95. Fermi trigger No 627645769: Global MASTER-Net observations report
  96. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  97. GRB 201121A: BALROG localization (Fermi Trigger 627614994 / GRB 201121062)
  98. IceCube Alert 201120.41: Global MASTER-Net observations report
  99. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS 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