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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 210704A: OAJ T80 multi-color detections
  2. GECAM detection of a bright short burst from SGR 1935+2154
  3. GRB 210706A: Swift-XRT afterglow detection
  4. Integral GRB210707.02: Global MASTER-Net observations report
  5. GRB 210706A: Swift ToO observations
  6. Fermi trigger No 647252274: Global MASTER-Net observations report
  7. INTEGRAL detection of a burst from SGR 1935+2154
  8. Integral GRB210706.72: Global MASTER-Net observations report
  9. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  10. GRB 210704A: OSIRIS/GTC spectroscopy
  11. GRB 210704A: CAHA 2.2m Afterglow Detection
  12. GRB 210704A: RATIR optical upper limits
  13. GRB 210704A: Swift/UVOT Upper Limits
  14. Konus-Wind detection of GRB 210704A
  15. GRB 210704B: AstroSat CZTI detection
  16. GRB 210619B: ALMA detection
  17. GRB 210704A: TNG detection of the optical afterglow candidate
  18. GRB 210704A: Assy optical afterglow candidate
  19. GRB 210704A: DDOTI upper limit
  20. GRB 210704B: Fermi GBM detection
  21. GRB 210704A: possible local hosts
  22. GRB 210704A: Fermi GBM detection
  23. GRB 210704A: Swift-XRT afterglow detection
  24. GRB 210704A: AstroSat CZTI detection
  25. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  26. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  27. GRB 210704A: Fermi-LAT detection
  28. GRB 210704A: Swift ToO observations
  29. GRB 210705A: AGILE/MCAL detection of a burst
  30. GRB 210704A: AGILE/MCAL detection
  31. Fermi trigger No 647108723: Global MASTER-Net observations report
  32. Fermi trigger No 647120009: Global MASTER-Net observations report
  33. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  34. GRB 210702A, Swift-BAT refined analysis
  35. GRB 210702A: BOOTES-3/YA optical counterpart observations
  36. Konus-Wind detection of GRB 210702A
  37. GRB 210702A: Chilescope optical observations
  38. GRB 210702A: iTelescope optical afterglow observations
  39. GRB 210702A: AGILE detection
  40. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  41. GRB 210619B: JCMT SCUBA-2 sub-mm observations
  42. GRB 210610B: JCMT SCUBA-2 sub-mm observations
  43. GRB 210610A: JCMT SCUBA-2 sub-mm observations
  44. GRB 210702A: Swift-XRT refined Analysis
  45. GRB 210702A: VLT/X-shooter redshift
  46. GRB 210702A: preliminary Swift/UVOT photometry
  47. GRB 210702A: Swift/UVOT redshift
  48. GRB210702A: MeerLICHT multi-colour photometry
  49. Swift GRB 210702A: Global MASTER-Net observations report
  50. Swift GRB210702.80: Global MASTER-Net OT detection
  51. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  52. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  53. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  54. IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  55. Fermi-LAT Gamma-ray Observations of IceCube-210629A
  56. IceCube-210629A: Upper limits from Fermi-GBM Observations
  57. GRB 210627B: GECAM detection
  58. IceCube Alert 210629.76: Global MASTER-Net observations report
  59. GRB 210619B: Sayan observatory 1.6-m telescope observations
  60. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 210626A: Swift/XRT afterglow confirmation
  62. GRB 210626A: Fermi GBM observation
  63. GRB 210626A: CAHA 2.2m telescope optical limit
  64. GRB 210619B: Deep CAHA 2.2m detection and late-time light curve behavior
  65. GRB 210626A: Ondrejov D50 optical limit
  66. GRB 210626A: GIT optical upper limit
  67. Fermi trigger No 646443989: Global MASTER-Net observations report
  68. Fermi GRB 210627B: Global MASTER-Net observations report
  69. GRB 210627B: BALROG localization (Fermi Trigger 646509445/ GRB 210627748)
  70. GRB 210627B: Fermi GBM Final Real-time Localization
  71. Fermi GRB 210627A: Global MASTER-Net observations report
  72. GRB 210627A: Fermi GBM Final Real-time Localization
  73. GRB 210626A: Swift-XRT afterglow detection
  74. Fermi trigger No 646322348: Global MASTER-Net observations report
  75. Fermi GRB 210626A: Global MASTER-Net observations report
  76. GRB 210626A: Swift ToO observations
  77. GRB 210626A: Swift/BAT-GUANO detection and arcminute localization
  78. GRB 150428A: late-time radio observations
  79. GRB 210626A: Fermi GBM Final Real-time Localization
  80. GRB 210618A: 1.5m OSN optical upper limit
  81. Fermi GRB 210625A: Global MASTER-Net observations report
  82. GRB210619B: optical afterglow detection from Konkoly Observatory
  83. GRB 210625A: Fermi GBM Final Real-time Localization
  84. IPN triangulation of GRB 210624A (short)
  85. GRB 210622A: Swift-XRT observations
  86. GRB 210610B: T-CAT optical observations
  87. GRB 210619B: ASIM observation
  88. Fermi trigger No 646189108: Global MASTER-Net observations report
  89. Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
  90. GRB 210618A: Swift-XRT afterglow detection
  91. Fermi trigger No 646194855: Global MASTER-Net observations report
  92. GRB 210622A: Swift ToO observations
  93. GRB 210619B: Even further SAO RAS optical observations
  94. GRB 210619B: Mini-MegaTORTORA early optical observations
  95. Fermi GRB 210622B: Global MASTER-Net observations report
  96. GRB 210622A: Fermi GBM detection
  97. GRB 210619B: Abbey Ridge Observatory optical afterglow observation
  98. GRB 210619B: SPI-ACS/INTEGRAL observations
  99. GRB 210619B: Further SAO RAS optical observations
  100. GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst

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