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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 170708A: Insight-HXMT detection
  2. Correction to GCN Circular 21305: Trigger 760835: Swift misidentification of GRS1716-249
  3. Trigger 760835: Swift misidentification of GRS1716-249
  4. LIGO/Virgo G288732: Konus-Wind observations
  5. GRB 170705A: Further RATIR Optical and NIR Observations and Steepening of Fading
  6. GRB 170705A: KAIT Optical Observations
  7. GRB 170705A: Insight-HXMT observation
  8. GRB 170705A: ISON/Terskol optical observations
  9. Konus-Wind observation of GRB 170705A
  10. GRB 170705A: Redshift from 10.4m GTC/OSIRIS
  11. GRB 170705A: Fermi GBM observation
  12. GRB 170705A: Swift-BAT refined analysis
  13. GRB 170705A: MITSuME Akeno Optical Observation
  14. GRB 170705A: Swift/UVOT Detection
  15. GRB 170705A: RATIR Optical and NIR Observations
  16. GRB 170705A: Swift-XRT refined Analysis
  17. GRB 170705A: MASTER-OAFA early OT observations
  18. GRB 170705A: Enhanced Swift-XRT position
  19. GRB 170705A: Swift detection of a burst with an optical counterpart
  20. GRB 170629A: Swift-XRT refined Analysis
  21. GRB 170629A: Swift-BAT refined analysis
  22. GRB 170629A: Enhanced Swift-XRT position
  23. GRB 170629A: Fermi GBM observation
  24. LIGO/Virgo G274296: Updated localization from LIGO data
  25. GRB 170629A: Swift detection of a burst
  26. GRB 170626B CALET Gamma-Ray Burst Monitor detection
  27. LIGO/Virgo G270580: Candidate retracted due to H1 data quality
  28. Konus-Wind observation of GRB 170626B
  29. IPN Triangulation of GRB 170626B
  30. Konus-Wind observation of GRB 170626A
  31. GRB 170626A: SAO RAS confirmation of OT fading
  32. GRB 170626A: TShAO optical observations
  33. GRB 170607A: 15 GHz upper limits from AMI
  34. GRB 170626A: Insight-HXMT observation
  35. GRB 170626A: OASDG optical observations
  36. GRB 170626A: MASTER-Tunka OT detection.
  37. GRB 170626A: Swift-BAT refined analysis
  38. GRB 170626A: TNG optical observations
  39. GRB 170626A: Afterglow detection from 1.5m OSN
  40. GRB 170626A: SAO RAS possible OT detection
  41. GRB 170626A: Swift-XRT refined Analysis
  42. GRB 170626A: Fermi GBM observation
  43. GRB 170626B: The first GRB detected by the Insight-HXMT X-ray Telescope (revised)
  44. GRB 170626A: Swift detection of a burst
  45. LIGO/Virgo G288732: Fermi GBM Upper Limits for the LIGO Trigger and LAT Candidate
  46. LIGO/Virgo G288732: Pan-STARRS coverage of the Fermi/LAT candidate position
  47. Swift trigger 758168 is probably not an astrophysical source
  48. Swift Trigger 758005 is Probably Not an Astrophysical Source
  49. GRB 170607A CALET Gamma-Ray Burst Monitor detection
  50. Konus-Wind observation of GRB 170616A
  51. IPN Triangulation of GRB 170616A (short/hard)
  52. GRB 170614A: AstroSat CZTI detection
  53. GRB 170614A CALET Gamma-Ray Burst Monitor detection
  54. GRB 170606A CALET Gamma-Ray Burst Monitor detection
  55. LIGO/Virgo G288732: VLA imaging of the possible Fermi/LAT counterpart
  56. Swift Trigger 756953: false identification by MASTER GCN 21250
  57. Swift Trigger 756953 is probably not an astrophysical source
  58. GRB170612.87 MASTER-Net OT detection
  59. LIGO/Virgo G288732: Kiso/KWFC optical imaging of the possible Fermi/LAT counterpart
  60. LIGO/Virgo G288732: HAWC follow-up
  61. Konus-Wind observation of GRB 170604A
  62. Konus-Wind observation of GRB 170607B
  63. LIGO/Virgo G288732: UKIRT near-IR imaging of the Fermi/LAT candidate
  64. LIGO/Virgo G288732: LBT optical imaging of the Fermi/LAT candidate
  65. GRB 170610A: MAXI/GSC detection
  66. IPN Triangulation of GRB 170607B
  67. LIGO/Virgo G288732 : MAXI/GSC observations
  68. GRB 170607A: Redshift from GTC/OSIRIS
  69. LIGO/Virgo G288732: Updated sky map from gravitational-wave data
  70. GRB 170607B: Fermi GBM detection
  71. GRB 170607A: ISON/Terskol optical observations
  72. LIGO/Virgo G288732: GWFUNC/NOWT observations of the skymap and follow-up of the Fermi/LAT candidate
  73. LIGO/Virgo G288732: Swift/UVOT follow up of the possible LAT counterpart
  74. LIGO/Virgo G288732: Swift/BAT data search
  75. LIGO/Virgo G288732: Swift-XRT follow up of the putative LAT counterpart
  76. GRB 170607B: AstroSat CZTI detection
  77. LIGO/Virgo G288732: INTEGRAL search for a prompt gamma-ray counterpart
  78. GRB 170607A: Swift-BAT refined analysis
  79. LIGO/Virgo G288732:SVOM/Mini-GWAC observations of the initial skymap
  80. LIGO/Virgo G288732: AGILE GRID Observations
  81. LIGO/Virgo G288732: Fermi-LAT detection of a weak candidate
  82. LIGO/Virgo G288732: IceCube neutrino observations update
  83. GRB 170607A: Correction on the possible host galaxy identification
  84. LIGO/Virgo G288732: AGILE MCAL Observations
  85. LIGO/Virgo G288732 ANTARES search
  86. LIGO/VIRGO G288732: Fermi GBM Observations
  87. LIGO/Virgo G288732: Identification of a GW Binary Merger Candidate
  88. GRB 170607A: Swift/UVOT Detection
  89. GRB 170607A: MASTER-Tavrida early OT observations
  90. GRB 170607A: Fermi GBM observation
  91. GRB 170607A: NOT optical afterglow detection
  92. GRB 170607A: Swift-XRT refined Analysis
  93. GRB 170607A: Enhanced Swift-XRT position
  94. GRB 170607A: Swift detection of a burst with a bright optical counterpart
  95. GRB 170526A: 15 GHz upper limits from AMI
  96. GRB 170524A: 15 GHz upper limits from AMI
  97. GRB 170519A: 15 GHz upper limits from AMI
  98. GRB 170531B: Zeiss-1000/CrAO optical observations
  99. GRB 170531B: WHT spectroscopy
  100. GRB 170519A: TShAO and AbAO optical observations

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