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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"

26339 results found.

  1. GECAM detection of a short burst from SGR 1935+2154
  2. GRB 210707A: A long GRB detected by INTEGRAL
  3. GRB 210708A: Swift detection of a burst
  4. Fermi trigger No 647271699: Global MASTER-Net observations report
  5. GRB 210706A: Fermi GBM observation
  6. GRB 210706A: GIT optical upper limits
  7. GRB 210704A: OAJ T80 multi-color detections
  8. GECAM detection of a bright short burst from SGR 1935+2154
  9. GRB 210706A: Swift-XRT afterglow detection
  10. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  11. GRB 210704A: OSIRIS/GTC spectroscopy
  12. GRB 210704A: RATIR optical upper limits
  13. GRB 210704A: Swift/UVOT Upper Limits
  14. GRB 210704A: TNG detection of the optical afterglow candidate
  15. GRB 210704A: Assy optical afterglow candidate
  16. GRB 210704A: DDOTI upper limit
  17. GRB 210704B: Fermi GBM detection
  18. GRB 210704A: possible local hosts
  19. GRB 210704A: Fermi GBM detection
  20. GRB 210704A: Swift-XRT afterglow detection
  21. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  22. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  23. Fermi trigger No 647108723: Global MASTER-Net observations report
  24. Fermi trigger No 647120009: Global MASTER-Net observations report
  25. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  26. GRB 210702A, Swift-BAT refined analysis
  27. GRB 210702A: Chilescope optical observations
  28. GRB 210702A: iTelescope optical afterglow observations
  29. GRB 210702A: Swift-XRT refined Analysis
  30. GRB 210702A: VLT/X-shooter redshift
  31. GRB 210702A: preliminary Swift/UVOT photometry
  32. GRB210702A: MeerLICHT multi-colour photometry
  33. Swift GRB210702.80: Global MASTER-Net OT detection
  34. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  35. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  37. Fermi-LAT Gamma-ray Observations of IceCube-210629A
  38. GRB 210627B: GECAM detection
  39. GRB 210619B: Sayan observatory 1.6-m telescope observations
  40. GRB 210626A: GIT optical upper limit
  41. GRB 210627B: BALROG localization (Fermi Trigger 646509445/ GRB 210627748)
  42. GRB 210626A: Swift-XRT afterglow detection
  43. Fermi trigger No 646322348: Global MASTER-Net observations report
  44. GRB 210626A: Swift/BAT-GUANO detection and arcminute localization
  45. GRB210619B: optical afterglow detection from Konkoly Observatory
  46. GRB 210622A: Swift-XRT observations
  47. GRB 210610B: T-CAT optical observations
  48. GRB 210619B: ASIM observation
  49. GRB 210618A: Swift-XRT afterglow detection
  50. GRB 210619B: Even further SAO RAS optical observations
  51. GRB 210619B: Mini-MegaTORTORA early optical observations
  52. GRB 210622A: Fermi GBM detection
  53. GRB 210619B: Further SAO RAS optical observations
  54. GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst
  55. GRB 210619B: possibility of lensed visible afterglow?
  56. GECAM detection of GRB 210622B
  57. GRB 210619B: AbAO optical observations
  58. Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
  59. Swift GRB210621.71: Global MASTER-Net observations report
  60. GRB 210619B: iTelescope optical afterglow observation
  61. GRB 210619B: SAO RAS optical observations
  62. GRB 210619B: SEDM Optical Observations
  63. GRB 210619B: REM optical/NIR afterglow detection
  64. GRB 210619B: GIT optical follow-up and confirmation of jet-break
  65. GRB 210619B: Swift-BAT refined analysis
  66. GRB 210619B: Liverpool Telescope First Hour Observations
  67. GRB 210619B: Fermi GBM detection
  68. GRB 210619B: Swift/UVOT Detection
  69. GRB 210619B: Liverpool telescope imaging of a red afterglow
  70. GRB 210619B: Swift-XRT refined Analysis
  71. GRB 210619B: SARA-KP 0.9m Optical Afterglow Detection
  72. GRB 210619B: Enhanced Swift-XRT position
  73. GRB 210619B: iTelescope T18 detection
  74. GECAM detection of GRB 210619B
  75. Swift GRB210619.99: Global MASTER-Net OT detection
  76. GRB 210619B: Swift detection of a bright burst and optical counterpart
  77. Swift GRB210619.99: Global MASTER-Net OT detection
  78. GRB 210619A: BALROG localization (Fermi Trigger 645799548 / GRB 210619532)
  79. GRB 210618A: Swift/UVOT Upper Limits
  80. GRB 210618A: Swift-BAT refined analysis
  81. GRB 210618A: Fermi GBM observation
  82. GRB 210618A: Swift-XRT observations
  83. GRB 210618A: DDOTI upper limit for the optical afterglow
  84. GRB 210618A: Swift detection of a burst
  85. GRB 210610B: Swift/UVOT Detection
  86. GRB 210610A: Swift/UVOT Detection
  87. GRB 210323B: Fermi GBM observation
  88. GRB 210610B: REM optical/NIR observations of the afterglow
  89. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  90. Swift ToO Observations of HAWC transient J0020+3108
  91. GRB 210605B: Swift-XRT afterglow detection
  92. GRB 210610A: Fermi GBM observations
  93. GRB 210610B: Further SAO RAS optical observations
  94. GRB 210610A: SAO RAS optical observations
  95. GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
  96. GRB 210421B: Fermi GBM detection
  97. GRB 210607C: AstroSat CZTI detection
  98. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  99. GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
  100. GRB 210610B: MITSuME Akeno optical observation

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