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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 210610B: iTelescope optical afterglow observations
  2. GRB 210610B: Further SAO RAS optical observations
  3. GRB 210610A: SAO RAS optical observations
  4. GRB 210610B: optical observations from Burke-Gaffney Observatory and Abbey Ridge Observatory
  5. GRB 210610B: Continued KAIT Optical Detection
  6. GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
  7. GRB 210421B: Fermi GBM detection
  8. Swift GRB210612.54: Global MASTER-Net observations report
  9. GRB 210607C: AstroSat CZTI detection
  10. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  11. GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
  12. GRB 210610B: MITSuME Akeno optical observation
  13. GRB 201228B: Fermi GBM observation
  14. GRB 210610B: VLA detection
  15. GRB 210610B: ALMA detection
  16. GRB 210610B: Liverpool Telescope optical photometry
  17. GRB 210610B: CrAO/ZTSH optical observations and light curve
  18. GRB 210610A: CrAO/ZTSH optical observations
  19. GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)
  20. GRB 210610A: CrAO/ZTSH optical observations
  21. GRB 210610A: CAHA 2.2m observations and light-curve behavior
  22. GRB 210606A: Fermi GBM detection
  23. GRB 210605B: Fermi GBM detection
  24. GRB 210610B: Swift-XRT refined Analysis
  25. GRB 210610B: Swift-BAT refined analysis
  26. GRB 210610B: Zwicky Transient Facility afterglow detection
  27. GRB 210610B: optical afterglow observations
  28. GRB 210610B: KAIT Optical Detection
  29. GRB 210610A: KAIT Optical Detection
  30. GRB 210607C: Insight-HXMT/HE detection
  31. GRB 210610B: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
  32. GRB 210610A: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
  33. GRB 210610B: Fermi GBM detection
  34. GRB 210610B: University of Siena Observatory optical photometry of the afterglow
  35. Konus-Wind detection of GRB 210610A
  36. Konus-Wind detection of GRB 210610B
  37. GRB 210610B: AGILE detection
  38. GRB 210610B: Redshift confirmation from GTC
  39. GRB 210610B: GOTO confirmation of afterglow detection
  40. GRB 210610A: Swift-XRT refined Analysis
  41. GRB 210610A: RATIR Optical and NIR Detection
  42. GRB 210610B: RATIR Optical and NIR Observations
  43. GRB 210610B: Enhanced Swift-XRT position
  44. GRB 210610B: Photometry and phot-redshift from Legacy Survey, PanSTAR, and SDSS
  45. GRB 210610B: SAO RAS optical observations
  46. GRB 210610A: Swift-BAT refined analysis
  47. GRB 210610A: 1.5m OSN optical observation
  48. GRB 210610B: correction to GCN 30181
  49. HAWC Transient Monitoring Alert: Significant Spot after 3 transits
  50. GRB 210610B: NOT optical observations and tentative redshift
  51. GRB 210610B: iTelescope optical afterglow observations
  52. GRB210610B: MeerLICHT multi-colour photometry
  53. Fermi trigger No 645047470: Global MASTER-Net observations report
  54. GRB 210610B: CrAO/ZTSh optical afterglow photometry
  55. GRB 210610B: BOOTES-2/TELMA optical observation
  56. Swift GRB 210610B: Global MASTER-Net observations report
  57. GRB 210610B: CrAO/ZTSh optical observations
  58. GRB 210610B: GIT optical detection
  59. Swift GRB210610.83: Global MASTER-Net OT detection
  60. GRB 210606A: Swift-XRT afterglow detection
  61. GRB 210610B: BALROG localization (Fermi Trigger 645047470 / GRB 210610827)
  62. GRB 210610B: Swift detection of a burst with bright optical afterglow
  63. GRB 210610A: MITSuME Ishigaki optical observation
  64. GRB210610A: MeerLICHT multi-colour photometry
  65. Swift GRB 210610A: Global MASTER-Net observations report
  66. Swift GRB 210610A: MASTER optical counterpart observation
  67. GRB 210610A: Enhanced Swift-XRT position
  68. GRB 210610A: Xinglong-2.16m redshift
  69. GRB 210610A: GIT optical detection
  70. GRB 210610A: Xinglong-2.16m optical afterglow observations
  71. GRB 210610A: MITSuME Akeno optical observation
  72. GRB 210610A: Swift detection of a burst with an optical counterpart
  73. GRB 210607B: Insight-HXMT/HE detection
  74. GRB 210605A: CALET Gamma-Ray Burst Monitor detection
  75. Konus-Wind detection of GRB 210606B
  76. Fermi-LAT Gamma-ray Observations of IceCube-210608A
  77. IceCube-210608A: not observable by Fermi-GBM
  78. IPN triangulation of GRB 210606B
  79. IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
  80. IceCube Alert 210608.15: Global MASTER-Net observations report
  81. Fermi Gamma-ray Burst Monitor trigger 644793834 / 210607892 is not a GRB
  82. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  83. MAXI GRB210607.82: Global MASTER-Net observations report
  84. Fermi trigger No 644793834: Global MASTER-Net observations report
  85. GRB 210606B: Fermi GBM detection
  86. GRB 210605B: Swift-XRT observations
  87. Konus-Wind detection of GRB 210602A
  88. Konus-Wind detection of GRB 210605A (short/hard)
  89. IPN triangulation of GRB 210605A (short)
  90. GRB 210606B: AGILE detection
  91. GRB 210606A: 1.5m OSN optical upper limit
  92. GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402
  93. GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
  94. GRB 210606B: GECAM detection
  95. Fermi trigger No 644712030: Global MASTER-Net observations report
  96. GRB 210606A: Swift ToO observations
  97. Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
  98. GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
  99. GRB 210605B: Swift ToO observations
  100. Fermi GRB 210606A: Global MASTER-Net observations report

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