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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 170607A: 15 GHz upper limits from AMI
  2. GRB 170626A: Insight-HXMT observation
  3. GRB 170626A: OASDG optical observations
  4. GRB 170626A: MASTER-Tunka OT detection.
  5. GRB 170626A: Swift-BAT refined analysis
  6. GRB 170626A: TNG optical observations
  7. GRB 170626A: Afterglow detection from 1.5m OSN
  8. GRB 170626A: SAO RAS possible OT detection
  9. GRB 170626A: Swift-XRT refined Analysis
  10. GRB 170626A: Fermi GBM observation
  11. GRB 170626B: The first GRB detected by the Insight-HXMT X-ray Telescope (revised)
  12. GRB 170626A: Swift detection of a burst
  13. LIGO/Virgo G288732: Fermi GBM Upper Limits for the LIGO Trigger and LAT Candidate
  14. LIGO/Virgo G288732: Pan-STARRS coverage of the Fermi/LAT candidate position
  15. Swift trigger 758168 is probably not an astrophysical source
  16. Swift Trigger 758005 is Probably Not an Astrophysical Source
  17. GRB 170607A CALET Gamma-Ray Burst Monitor detection
  18. Konus-Wind observation of GRB 170616A
  19. IPN Triangulation of GRB 170616A (short/hard)
  20. GRB 170614A: AstroSat CZTI detection
  21. GRB 170614A CALET Gamma-Ray Burst Monitor detection
  22. GRB 170606A CALET Gamma-Ray Burst Monitor detection
  23. LIGO/Virgo G288732: VLA imaging of the possible Fermi/LAT counterpart
  24. Swift Trigger 756953: false identification by MASTER GCN 21250
  25. Swift Trigger 756953 is probably not an astrophysical source
  26. GRB170612.87 MASTER-Net OT detection
  27. LIGO/Virgo G288732: Kiso/KWFC optical imaging of the possible Fermi/LAT counterpart
  28. LIGO/Virgo G288732: HAWC follow-up
  29. Konus-Wind observation of GRB 170604A
  30. Konus-Wind observation of GRB 170607B
  31. LIGO/Virgo G288732: UKIRT near-IR imaging of the Fermi/LAT candidate
  32. LIGO/Virgo G288732: LBT optical imaging of the Fermi/LAT candidate
  33. GRB 170610A: MAXI/GSC detection
  34. IPN Triangulation of GRB 170607B
  35. LIGO/Virgo G288732 : MAXI/GSC observations
  36. GRB 170607A: Redshift from GTC/OSIRIS
  37. LIGO/Virgo G288732: Updated sky map from gravitational-wave data
  38. GRB 170607B: Fermi GBM detection
  39. GRB 170607A: ISON/Terskol optical observations
  40. LIGO/Virgo G288732: GWFUNC/NOWT observations of the skymap and follow-up of the Fermi/LAT candidate
  41. LIGO/Virgo G288732: Swift/UVOT follow up of the possible LAT counterpart
  42. LIGO/Virgo G288732: Swift/BAT data search
  43. LIGO/Virgo G288732: Swift-XRT follow up of the putative LAT counterpart
  44. GRB 170607B: AstroSat CZTI detection
  45. LIGO/Virgo G288732: INTEGRAL search for a prompt gamma-ray counterpart
  46. GRB 170607A: Swift-BAT refined analysis
  47. LIGO/Virgo G288732:SVOM/Mini-GWAC observations of the initial skymap
  48. LIGO/Virgo G288732: AGILE GRID Observations
  49. LIGO/Virgo G288732: Fermi-LAT detection of a weak candidate
  50. LIGO/Virgo G288732: IceCube neutrino observations update
  51. GRB 170607A: Correction on the possible host galaxy identification
  52. LIGO/Virgo G288732: AGILE MCAL Observations
  53. LIGO/Virgo G288732 ANTARES search
  54. LIGO/VIRGO G288732: Fermi GBM Observations
  55. LIGO/Virgo G288732: Identification of a GW Binary Merger Candidate
  56. GRB 170607A: Swift/UVOT Detection
  57. GRB 170607A: MASTER-Tavrida early OT observations
  58. GRB 170607A: Fermi GBM observation
  59. GRB 170607A: NOT optical afterglow detection
  60. GRB 170607A: Swift-XRT refined Analysis
  61. GRB 170607A: Enhanced Swift-XRT position
  62. GRB 170607A: Swift detection of a burst with a bright optical counterpart
  63. GRB 170526A: 15 GHz upper limits from AMI
  64. GRB 170524A: 15 GHz upper limits from AMI
  65. GRB 170519A: 15 GHz upper limits from AMI
  66. GRB 170531B: Zeiss-1000/CrAO optical observations
  67. GRB 170531B: WHT spectroscopy
  68. GRB 170519A: TShAO and AbAO optical observations
  69. GRB 170604A: Swift/UVOT Observations
  70. GRB 170519A: Mondy optical observations
  71. GRB 170529A: AstroSat CZTI detection
  72. GRB 170604A: RATIR Optical and NIR Observations
  73. GRB 170604A: AbAO optical observations
  74. Swift trigger 755873: Swift BAT and XRT refined analysis
  75. GRB 170522A: confirmation of the X-ray afterglow
  76. GROND observations of GRB170604A
  77. Swift Trigger 755873: MASTER Net optical observations
  78. GRB 170604A: Swift-XRT refined Analysis
  79. GRB 170604A: GTC spectroscopic redshift
  80. GRB 170604A: Enhanced Swift-XRT position
  81. GRB 170604A: Swift-BAT refined analysis
  82. Swift Trigger 755873: D50 optical limits
  83. Swift Trigger 755873: a possible GRB
  84. GRB 170604A: optical observations
  85. GRB 170604A: Swift detection of a burst
  86. Trigger 755848: Swift spurious trigger on Cen X-3
  87. GRB 170531B: ISON/Terskol optical observations
  88. GRB 170531B: Swift/UVOT Detection
  89. GRB 170531B: SMARTS optical/IR observations
  90. GRB 170531B: Swift-BAT refined analysis
  91. GRB 170531A: Swift/UVOT Upper Limits
  92. GRB 170531B: LCO observations
  93. GRB 170531B: Swift-XRT refined Analysis
  94. GRB 170531A: MASTER Net job
  95. GRB 170531A: Swift-XRT refined Analysis
  96. GRB 170531B: MASTER Net optical counterpart refind position and magnitude
  97. GROND observations of GRB 170531B
  98. GRB 170531B: Redshift from GTC/OSIRIS
  99. GRB 170531A: ePESSTO NTT observations
  100. GRB 170531B: Enhanced Swift-XRT position

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