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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 200509A: Swift-XRT refined Analysis
  2. GRB 200509A: Enhanced Swift-XRT position
  3. GRB 200509A: Zadko observatory - Gingin optical upper limits
  4. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  5. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  6. GRB 200507A: Fermi GBM Final Real-time Localization
  7. GRB 200506A: AstroSat CZTI detection
  8. GRB 200506C: AstroSat CZTI detection
  9. Swift Detection of a burst from SGR Swift J1818.0-1607
  10. Swift GRB200506.73: Global MASTER-Net observations report
  11. GRB 200422A: INTEGRAL observations
  12. GRB 200505A: AGILE detection
  13. GRB 200506C: Fermi GBM Final Real-time Localization
  14. GRB 200506B: Fermi GBM Final Real-time Localization
  15. GRB 200506A: Fermi GBM Final Real-time Localization
  16. GRB 200505A: Fermi GBM Final Real-time Localization
  17. Insight-HXMT detection of a short bright burst from SGR 1935+2154
  18. AGILE detection of a short and hard X-ray burst possibly related to SGR 1935+2154
  19. GRB 200502A: AstroSat CZTI detection
  20. GRB 200503A: AGILE observations
  21. GRB 200502A: AGILE observations
  22. GRB 200503B: BALROG localization (Fermi Trigger 610219118 / GRB 200503721)
  23. GRB 200503B: Fermi GBM Final Real-time Localization
  24. Geocentric time correction for Insight-HXMT detection of the x-ray counterpart of the FRB by CHIME and STARE2 from SGR 1935+2154
  25. AstroSat CZTI detection : GRB200503A
  26. Insight-HXMT X-ray and hard X-ray upper limits to the radio burst detected by FAST from SGR 1935+2154
  27. No optical bursts detected from SGR J1935+2154 by 24 fps observations with Tomo-e Gozen
  28. GRB 200502A: Fermi GBM Final Real-time Localization
  29. GRB 200424A: Swift-XRT afterglow detection
  30. Insight-HXMT X-ray and hard X-ray detection of the double peaks of the Fast Radio Burst from SGR 1935+2154
  31. Fermi GBM observation of a flare from the magnetar SGR 1806-20
  32. GRB 200501A: Fermi GBM Final Real-time Localization
  33. Trigger 968731: Swift detection of SGR1806-20
  34. Fermi GBM trigger 200429866/609886052 is not a GRB
  35. SGR 1935+2154: MASTER optical observations
  36. Konus-Wind observation of hard X-ray counterpart of the radio burst from SGR 1935+2154
  37. SGR 1935+2154: INTEGRAL hard X-ray counterpart of radio burst
  38. Konus-Wind observation of a very intense bursting activity of SGR 1935+2154
  39. Integral GRB200428.61: Global MASTER-Net observations report
  40. A Forest of Bursts from SGR 1935+2154
  41. SGR 1935+2154: AstroSat CZTI detections
  42. high bursting activity of SGR 1935+2154: CGBM observations
  43. SGR 1935+2154 the Insight-HXMT observation plan
  44. SGR 1935+2154: MAXI/GSC detection
  45. Fermi GBM observation of a bright flare from magnetar SGR 1935+2154
  46. IceCube-200425A: No significant detection in HAWC
  47. Swift detection of multiple bursts from SGR 1935+2154
  48. IceCube-200425A: Upper limits from a search for additional neutrino events in IceCube
  49. IceCube-200425A: Upper limits from Fermi-GBM Observations
  50. Fermi-LAT Gamma-ray Observations of IceCube-200425A
  51. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  52. IceCube-200425A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  53. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  54. GRB 200425A: Swift-BAT refined analysis
  55. IceCube Alert 200425.98: Global MASTER-Net observations report
  56. GRB 200424A: Swift/UVOT Upper Limits
  57. IPN triangulation of GRB 200423A (short)
  58. GRB 200425A: LCO Optical Upper Limits
  59. Swift GRB 200425A: Global MASTER-Net observations report
  60. GRB 200425B: Fermi GBM Final Real-time Localization
  61. GRB 200425A: Swift/UVOT Upper Limits
  62. GRB 200424A: AstroSat CZTI detection
  63. GRB 200425A: Swift-XRT refined Analysis
  64. GRB 200424A: Swift-XRT observations
  65. GRB 200425A: Enhanced Swift-XRT position
  66. GRB 200425A: Swift detection of a burst
  67. GRB 200424A: LCO Optical Upper Limit
  68. GRB 200424A: Swift ToO observations
  69. Konus-Wind observation of GRB 200422A
  70. GRB 200424A: a long GRB detected by INTEGRAL
  71. Fermi GRB 200423A: Global MASTER-Net observations report
  72. GRB 200423A: Fermi GBM Final Real-time Localization
  73. Konus-Wind observation of a bright burst from SGR 1935+2154
  74. GRB 200422A: AstroSat CZTI detection
  75. GRB 200415A correction to GCN 27627 (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  76. GRB 200422A: MASTER optical observations
  77. GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  78. IPN triangulation of GRB 200422A (long/very bright)
  79. IPN Triangulation of a bright burst from SGR 1935+2154
  80. IceCube-200421A: Upper limits from a search for additional neutrino events in IceCube
  81. bright SGR burst detected by CALET Gamma-Ray Burst Monitor
  82. GRB 200415A: ASIM observation
  83. GRB 200410A: Liverpool Telescope First Hour Observations
  84. Fermi-LAT Gamma-ray Observations of IceCube-200421A
  85. IceCube-200421A: No Neutrino Counterpart in ANTARES data
  86. Fermi GRB 200421A: Global MASTER-Net observations report
  87. IceCube-200421A: No significant detection in HAWC
  88. GRB 200421A: Fermi GBM Final Real-time Localization
  89. IceCube-200421A: not observable by Fermi-GBM
  90. IceCube Alert 200421.02: Global MASTER-Net observations report
  91. IceCube-200421A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  92. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  93. IceCube Alert 200420.97: Global MASTER-Net observations report
  94. GRB 200412B: continued Mondy and Terskol optical observations
  95. GRB 200420: Fermi GBM Final Localization Correction
  96. Fermi GRB 200420A: Global MASTER-Net observations report
  97. GRB 200420A: Fermi GBM Final Real-time Localization
  98. Fermi trigger No 608935505: Global MASTER-Net observations report
  99. GRB 200412B: continued Terskol optical observations
  100. GRB 200412B: continued AbAO, Mondy, TSHAO, Terskol optical observations

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