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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. Fermi GRB 200714A: Global MASTER-Net observations report
  2. GRB 200522A: Candidate Optical/nIR Counterpart from Gemini and HST Imaging
  3. GRB 200714E: BALROG localization (Fermi Trigger 616444510 / GRB 200714774)
  4. GRB 200714E: Fermi GBM Final Real-time Localization
  5. GRB 200714D: Fermi GBM Final Real-time Localization
  6. GRB 200713A: Swift-BAT refined analysis
  7. GRB 200714C: Fermi GBM Final Real-time Localization
  8. GRB 200711A: Insight-HXMT/HE detection
  9. GRB 200714B: Fermi GBM Final Real-time Localization
  10. GRB 200713A: Swift-XRT refined Analysis
  11. GRB 200714A: Fermi GBM Final Real-time Localization
  12. Fermi trigger No 616370565: Global MASTER-Net observations report
  13. GRB 200713A: Enhanced Swift-XRT position
  14. GRB 200713A: Swift detection of a burst
  15. GRB 200711A: CALET Gamma-Ray Burst Monitor detection
  16. GRB 200711A: AbAO optical upper limit
  17. GRB 200711A: Swift/UVOT Upper Limits
  18. GRB 200711A: Swift-BAT refined analysis
  19. GRB 200711A: Fermi-LAT marginal detection
  20. GRB 200711A: KAIT Optical Upper Limit
  21. GRB 200711A: Swift-XRT refined Analysis
  22. GRB 200711A: Fermi GBM detection
  23. Swift GRB 200711A: Global MASTER-Net observations report
  24. GRB 200711A: Swift detection of a burst
  25. GRB 200711A: Fermi GBM Final Real-time Localization
  26. Update of alert from the HAWC Burst Monitor HAWC-200709A
  27. GRB 200709B/HAWC-200907A: Swift-XRT further observations
  28. HAWC-200907A: No Neutrino Counterpart detected with ANTARES
  29. GRB 200710A: Fermi GBM Final Real-time Localization
  30. GRB 200709B: Swift-XRT observations
  31. GRB 200709B: Tiled Swift observations
  32. GRB 200709A: Fermi GBM Final Real-time Localization
  33. GRB 200707A: Insight-HXMT/HE detection
  34. GRB 200707A: Fermi GBM Final Localization
  35. Fermi trigger No 615741133: Global MASTER-Net observations report
  36. GRB 200704A: Insight-HXMT/HE detection
  37. GRB 200706A: Fermi GBM Final Real-time Localization
  38. Fermi GRB 200705A: Global MASTER-Net observations report
  39. Fermi-LAT-ANTARES 200407a Coincidence
  40. GRB 200705A: Fermi GBM Final Real-time Localization
  41. GRB 200703B: Insight-HXMT/HE detection
  42. GRB 200703B: AstroSat CZTI detection
  43. GRB 200703B: Fermi GBM Final Real-time Localization
  44. GRB 200703A: Fermi GBM Final Real-time Localization
  45. Fermi GRB 200702A: Global MASTER-Net observations report
  46. GRB 200702A: Fermi GBM Final Real-time Localization
  47. Trigger 980513: Swift detection of SGR Swift J1818.0-1607
  48. GRB 200701A: Swift-BAT refined analysis
  49. Fermi-GBM Sub-Threshold Detection of GRB 200701A
  50. GRB 200701A: Swift detection of a burst
  51. GRB 200630A: Swift-BAT refined analysis
  52. GRB 200630A: Swift/UVOT Upper Limits
  53. GRB 200630A: Swift-XRT refined Analysis
  54. GRB 200630B: Fermi GBM Final Localization
  55. GRB 200623A: Swift XRT further observations
  56. GRB 200630A: Fermi GBM detection
  57. GRB 200629A: AstroSat CZTI detection
  58. GRB 200630A: Enhanced Swift-XRT position
  59. GRB 200630A: Swift detection of a burst
  60. Fermi trigger No 615174580: Global MASTER-Net observations report
  61. Fermi GRB 200629A: Global MASTER-Net observations report
  62. GRB 200629A: Fermi GBM Final Real-time Localization
  63. GRB 200629A: BALROG localization (Fermi Trigger 615127794 / GRB 200629535)
  64. GRB 200522A: Gemini North spectroscopy of the putative host galaxy
  65. Konus-Wind detection of short/hard GRB 200623B
  66. GRB 200623A: Further MMTCam Observations of XRT Source #3
  67. GRB 200625A: Fermi-LAT detection is likely a flare from PKS 1127-14
  68. GRB 200623A: LBT optical observations
  69. GRB 200623A : SMA observations at Swift/XRT Source #3
  70. Fermi GRB 200626A: Global MASTER-Net observations report
  71. GRB 200625A: Swift ToO observations
  72. GRB 200626A: Fermi GBM Final Real-time Localization
  73. Fermi GRB 200625A: Global MASTER-Net observations report
  74. GRB 200625A: Fermi GBM Final Real-time Localization
  75. Updated catalog of X-ray bursts of SGR J1935+2154 from Insight-HXMT observations
  76. GRB 200623A: MMT observations at XRT Source #3
  77. GRB 200623A: Swift/UVOT Upper Limits
  78. IPN triangulation of GRB 200623B (short)
  79. GRB 200623A: Swift-XRT observations
  80. GRB 200623A: OAJ deep multi-color imaging, XRT #2 is pre-detected
  81. GRB 200623A: TNG optical observations
  82. GRB 200623A: AbAO afterglow candidate within XRT #2
  83. GRB 200623A: Fermi GBM observation
  84. Fermi GRB 200623B: Global MASTER-Net observations report
  85. GRB 200623B: Fermi GBM Final Real-time Localization
  86. GRB 200623A: Correction to GCN 28013
  87. GRB 200623A: Swift ToO observations
  88. IceCube-200620A: No significant detection in HAWC
  89. GRB 200623A: Swift/BAT-GUANO detection and arcminute localization of a short GRB
  90. Fermi GRB 200623A: Global MASTER-Net observations report
  91. GRB 200623A: Fermi GBM Final Real-time Localization
  92. IceCube-200620A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-200620A: INTEGRAL was inactive at the time of the event
  94. GRB 200622A: Fermi GBM Final Real-time Localization
  95. IceCube-200620A: MASTER previous detection of ZTF20abgvabi/AT2020ncr
  96. IceCube-200620A: not observable by Fermi-GBM
  97. IceCube-200620A: One Candidate Counterpart from the Zwicky Transient Facility
  98. Fermi-LAT Gamma-ray Observations of IceCube-200620A
  99. GRB 200613A: Continued CrAO optical observations
  100. IceCube-200620A: No ANTARES neutrino counterpart

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