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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 200711A: KAIT Optical Upper Limit
  2. GRB 200711A: Swift-XRT refined Analysis
  3. GRB 200711A: Fermi GBM detection
  4. Swift GRB 200711A: Global MASTER-Net observations report
  5. GRB 200711A: Swift detection of a burst
  6. GRB 200711A: Fermi GBM Final Real-time Localization
  7. Update of alert from the HAWC Burst Monitor HAWC-200709A
  8. GRB 200709B/HAWC-200907A: Swift-XRT further observations
  9. HAWC-200907A: No Neutrino Counterpart detected with ANTARES
  10. GRB 200710A: Fermi GBM Final Real-time Localization
  11. GRB 200709B: Swift-XRT observations
  12. GRB 200709B: Tiled Swift observations
  13. GRB 200709A: Fermi GBM Final Real-time Localization
  14. GRB 200707A: Insight-HXMT/HE detection
  15. GRB 200707A: Fermi GBM Final Localization
  16. Fermi trigger No 615741133: Global MASTER-Net observations report
  17. GRB 200704A: Insight-HXMT/HE detection
  18. GRB 200706A: Fermi GBM Final Real-time Localization
  19. Fermi GRB 200705A: Global MASTER-Net observations report
  20. Fermi-LAT-ANTARES 200407a Coincidence
  21. GRB 200705A: Fermi GBM Final Real-time Localization
  22. GRB 200703B: Insight-HXMT/HE detection
  23. GRB 200703B: AstroSat CZTI detection
  24. GRB 200703B: Fermi GBM Final Real-time Localization
  25. GRB 200703A: Fermi GBM Final Real-time Localization
  26. Fermi GRB 200702A: Global MASTER-Net observations report
  27. GRB 200702A: Fermi GBM Final Real-time Localization
  28. Trigger 980513: Swift detection of SGR Swift J1818.0-1607
  29. GRB 200701A: Swift-BAT refined analysis
  30. Fermi-GBM Sub-Threshold Detection of GRB 200701A
  31. GRB 200701A: Swift detection of a burst
  32. GRB 200630A: Swift-BAT refined analysis
  33. GRB 200630A: Swift/UVOT Upper Limits
  34. GRB 200630A: Swift-XRT refined Analysis
  35. GRB 200630B: Fermi GBM Final Localization
  36. GRB 200623A: Swift XRT further observations
  37. GRB 200630A: Fermi GBM detection
  38. GRB 200629A: AstroSat CZTI detection
  39. GRB 200630A: Enhanced Swift-XRT position
  40. GRB 200630A: Swift detection of a burst
  41. Fermi trigger No 615174580: Global MASTER-Net observations report
  42. Fermi GRB 200629A: Global MASTER-Net observations report
  43. GRB 200629A: Fermi GBM Final Real-time Localization
  44. GRB 200629A: BALROG localization (Fermi Trigger 615127794 / GRB 200629535)
  45. GRB 200522A: Gemini North spectroscopy of the putative host galaxy
  46. Konus-Wind detection of short/hard GRB 200623B
  47. GRB 200623A: Further MMTCam Observations of XRT Source #3
  48. GRB 200625A: Fermi-LAT detection is likely a flare from PKS 1127-14
  49. GRB 200623A: LBT optical observations
  50. GRB 200623A : SMA observations at Swift/XRT Source #3
  51. Fermi GRB 200626A: Global MASTER-Net observations report
  52. GRB 200625A: Swift ToO observations
  53. GRB 200626A: Fermi GBM Final Real-time Localization
  54. Fermi GRB 200625A: Global MASTER-Net observations report
  55. GRB 200625A: Fermi GBM Final Real-time Localization
  56. Updated catalog of X-ray bursts of SGR J1935+2154 from Insight-HXMT observations
  57. GRB 200623A: MMT observations at XRT Source #3
  58. GRB 200623A: Swift/UVOT Upper Limits
  59. IPN triangulation of GRB 200623B (short)
  60. GRB 200623A: Swift-XRT observations
  61. GRB 200623A: OAJ deep multi-color imaging, XRT #2 is pre-detected
  62. GRB 200623A: TNG optical observations
  63. GRB 200623A: AbAO afterglow candidate within XRT #2
  64. GRB 200623A: Fermi GBM observation
  65. Fermi GRB 200623B: Global MASTER-Net observations report
  66. GRB 200623B: Fermi GBM Final Real-time Localization
  67. GRB 200623A: Correction to GCN 28013
  68. GRB 200623A: Swift ToO observations
  69. IceCube-200620A: No significant detection in HAWC
  70. GRB 200623A: Swift/BAT-GUANO detection and arcminute localization of a short GRB
  71. Fermi GRB 200623A: Global MASTER-Net observations report
  72. GRB 200623A: Fermi GBM Final Real-time Localization
  73. IceCube-200620A: Upper limits from a search for additional neutrino events in IceCube
  74. IceCube-200620A: INTEGRAL was inactive at the time of the event
  75. GRB 200622A: Fermi GBM Final Real-time Localization
  76. IceCube-200620A: MASTER previous detection of ZTF20abgvabi/AT2020ncr
  77. IceCube-200620A: not observable by Fermi-GBM
  78. IceCube-200620A: One Candidate Counterpart from the Zwicky Transient Facility
  79. Fermi-LAT Gamma-ray Observations of IceCube-200620A
  80. GRB 200613A: Continued CrAO optical observations
  81. IceCube-200620A: No ANTARES neutrino counterpart
  82. IceCube Alert 200620.13: Global MASTER-Net observations report
  83. GRB 200613A: CrAO optical observations
  84. GRB 200613A: R-band observations from HCT
  85. GRB 200613A: Further Liverpool Telescope observations
  86. IceCube-200620A - IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 200619C: Fermi GBM Final Real-time Localization
  88. Fermi GRB 200619B: Global MASTER-Net observations report
  89. GRB 200619B: AstroSat CZTI detection
  90. GRB 200619A: Fermi GBM observation
  91. Fermi trigger No 614239407: Global MASTER-Net observations report
  92. GRB 200619A: AGILE detection
  93. LIGO/Virgo MS200618aq: Retraction of a test binary neutron star candidate
  94. LIGO/Virgo MS200619bf: Retraction of a test binary neutron star candidate
  95. LIGO/Virgo MS200618bx: Retraction of a test binary neutron star candidate
  96. LIGO/Virgo MS200618bq: Retraction of a test binary neutron star candidate
  97. GRB 200619B: Fermi GBM Final Real-time Localization
  98. GRB 200619A: Insight-HXMT/HE detection
  99. Fermi trigger No 614226976: Global MASTER-Net observations report
  100. GRB 200613A: continued Kitab optical observations

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