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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"

27394 results found.

  1. GRB 210622A: Swift-XRT observations
  2. GRB 210610B: T-CAT optical observations
  3. GRB 210619B: ASIM observation
  4. GRB 210618A: Swift-XRT afterglow detection
  5. GRB 210619B: Even further SAO RAS optical observations
  6. GRB 210619B: Mini-MegaTORTORA early optical observations
  7. GRB 210622A: Fermi GBM detection
  8. GRB 210619B: Further SAO RAS optical observations
  9. GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst
  10. GRB 210619B: possibility of lensed visible afterglow?
  11. GECAM detection of GRB 210622B
  12. GRB 210619B: AbAO optical observations
  13. Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
  14. Swift GRB210621.71: Global MASTER-Net observations report
  15. GRB 210619B: iTelescope optical afterglow observation
  16. GRB 210619B: SAO RAS optical observations
  17. GRB 210619B: SEDM Optical Observations
  18. GRB 210619B: REM optical/NIR afterglow detection
  19. GRB 210619B: GIT optical follow-up and confirmation of jet-break
  20. GRB 210619B: Swift-BAT refined analysis
  21. GRB 210619B: Liverpool Telescope First Hour Observations
  22. GRB 210619B: Fermi GBM detection
  23. GRB 210619B: Swift/UVOT Detection
  24. GRB 210619B: Liverpool telescope imaging of a red afterglow
  25. GRB 210619B: Swift-XRT refined Analysis
  26. GRB 210619B: SARA-KP 0.9m Optical Afterglow Detection
  27. GRB 210619B: Enhanced Swift-XRT position
  28. GRB 210619B: iTelescope T18 detection
  29. GECAM detection of GRB 210619B
  30. Swift GRB210619.99: Global MASTER-Net OT detection
  31. GRB 210619B: Swift detection of a bright burst and optical counterpart
  32. Swift GRB210619.99: Global MASTER-Net OT detection
  33. GRB 210619A: BALROG localization (Fermi Trigger 645799548 / GRB 210619532)
  34. GRB 210618A: Swift/UVOT Upper Limits
  35. GRB 210618A: Swift-BAT refined analysis
  36. GRB 210618A: Fermi GBM observation
  37. GRB 210618A: Swift-XRT observations
  38. GRB 210618A: DDOTI upper limit for the optical afterglow
  39. GRB 210618A: Swift detection of a burst
  40. GRB 210610B: Swift/UVOT Detection
  41. GRB 210610A: Swift/UVOT Detection
  42. GRB 210323B: Fermi GBM observation
  43. GRB 210610B: REM optical/NIR observations of the afterglow
  44. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  45. Swift ToO Observations of HAWC transient J0020+3108
  46. GRB 210605B: Swift-XRT afterglow detection
  47. GRB 210610A: Fermi GBM observations
  48. GRB 210610B: Further SAO RAS optical observations
  49. GRB 210610A: SAO RAS optical observations
  50. GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
  51. GRB 210421B: Fermi GBM detection
  52. GRB 210607C: AstroSat CZTI detection
  53. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  54. GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
  55. GRB 210610B: MITSuME Akeno optical observation
  56. GRB 201228B: Fermi GBM observation
  57. GRB 210610B: Liverpool Telescope optical photometry
  58. GRB 210610A: CrAO/ZTSH optical observations
  59. GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)
  60. GRB 210610A: CrAO/ZTSH optical observations
  61. GRB 210606A: Fermi GBM detection
  62. GRB 210605B: Fermi GBM detection
  63. GRB 210610B: Swift-XRT refined Analysis
  64. GRB 210610B: Swift-BAT refined analysis
  65. GRB 210610B: Zwicky Transient Facility afterglow detection
  66. GRB 210610B: optical afterglow observations
  67. GRB 210607C: Insight-HXMT/HE detection
  68. GRB 210610B: Fermi GBM detection
  69. GRB 210610B: University of Siena Observatory optical photometry of the afterglow
  70. GRB 210610B: GOTO confirmation of afterglow detection
  71. GRB 210610A: Swift-XRT refined Analysis
  72. GRB 210610A: RATIR Optical and NIR Detection
  73. GRB 210610B: RATIR Optical and NIR Observations
  74. GRB 210610B: Enhanced Swift-XRT position
  75. GRB 210610B: SAO RAS optical observations
  76. GRB 210610A: Swift-BAT refined analysis
  77. GRB 210610B: correction to GCN 30181
  78. HAWC Transient Monitoring Alert: Significant Spot after 3 transits
  79. GRB 210610B: iTelescope optical afterglow observations
  80. GRB210610B: MeerLICHT multi-colour photometry
  81. GRB 210610B: CrAO/ZTSh optical afterglow photometry
  82. GRB 210610B: GIT optical detection
  83. Swift GRB210610.83: Global MASTER-Net OT detection
  84. GRB 210606A: Swift-XRT afterglow detection
  85. GRB 210610B: BALROG localization (Fermi Trigger 645047470 / GRB 210610827)
  86. GRB 210610B: Swift detection of a burst with bright optical afterglow
  87. GRB 210610A: MITSuME Ishigaki optical observation
  88. GRB210610A: MeerLICHT multi-colour photometry
  89. GRB 210610A: Enhanced Swift-XRT position
  90. GRB 210610A: GIT optical detection
  91. GRB 210610A: Xinglong-2.16m optical afterglow observations
  92. GRB 210610A: MITSuME Akeno optical observation
  93. GRB 210610A: Swift detection of a burst with an optical counterpart
  94. GRB 210607B: Insight-HXMT/HE detection
  95. Fermi-LAT Gamma-ray Observations of IceCube-210608A
  96. IPN triangulation of GRB 210606B
  97. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  98. MAXI GRB210607.82: Global MASTER-Net observations report
  99. Fermi trigger No 644793834: Global MASTER-Net observations report
  100. GRB 210606B: Fermi GBM detection

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