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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. Insight-HXMT's continued observation plan for SGR J1935+2154
  2. Baksan Neutrino Observatory Alert 200511.76: Global MASTER-Net observations report
  3. GRB 200510A: AstroSat CZTI detection
  4. Konus-Wind observation of SGR 1935+2154 activity on 2020 May 10
  5. IPN triangulation of a bright burst from SGR 1935+2154 on 2020-05-10 at 06:12 UT
  6. GRB 200509A: Swift-BAT refined analysis
  7. GRB 200510A: BALROG localization (Fermi Trigger 610800081 / GRB 200510445)
  8. GRB 200510A: Fermi GBM Final Real-time Localization
  9. GRB 200509A: GROWTH-India r band upper limits
  10. GRB 200509A: Swift/UVOT Detection
  11. GRB 200509C: Fermi GBM Final Real-time Localization
  12. GRB 200509B: Fermi GBM Final Real-time Localization
  13. Swift GRB 200509A: Global MASTER-Net observations report
  14. GRB 200509A: LCO Optical Afterglow Detection
  15. GRB 200509A: Swift-XRT refined Analysis
  16. GRB 200509A: Enhanced Swift-XRT position
  17. GRB 200509A: Zadko observatory - Gingin optical upper limits
  18. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  19. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  20. GRB 200507A: Fermi GBM Final Real-time Localization
  21. GRB 200506A: AstroSat CZTI detection
  22. GRB 200506C: AstroSat CZTI detection
  23. Swift Detection of a burst from SGR Swift J1818.0-1607
  24. Swift GRB200506.73: Global MASTER-Net observations report
  25. GRB 200422A: INTEGRAL observations
  26. GRB 200505A: AGILE detection
  27. GRB 200506C: Fermi GBM Final Real-time Localization
  28. GRB 200506B: Fermi GBM Final Real-time Localization
  29. GRB 200506A: Fermi GBM Final Real-time Localization
  30. GRB 200505A: Fermi GBM Final Real-time Localization
  31. Insight-HXMT detection of a short bright burst from SGR 1935+2154
  32. AGILE detection of a short and hard X-ray burst possibly related to SGR 1935+2154
  33. GRB 200502A: AstroSat CZTI detection
  34. GRB 200503A: AGILE observations
  35. GRB 200502A: AGILE observations
  36. GRB 200503B: BALROG localization (Fermi Trigger 610219118 / GRB 200503721)
  37. GRB 200503B: Fermi GBM Final Real-time Localization
  38. Geocentric time correction for Insight-HXMT detection of the x-ray counterpart of the FRB by CHIME and STARE2 from SGR 1935+2154
  39. AstroSat CZTI detection : GRB200503A
  40. Insight-HXMT X-ray and hard X-ray upper limits to the radio burst detected by FAST from SGR 1935+2154
  41. No optical bursts detected from SGR J1935+2154 by 24 fps observations with Tomo-e Gozen
  42. GRB 200502A: Fermi GBM Final Real-time Localization
  43. GRB 200424A: Swift-XRT afterglow detection
  44. Insight-HXMT X-ray and hard X-ray detection of the double peaks of the Fast Radio Burst from SGR 1935+2154
  45. Fermi GBM observation of a flare from the magnetar SGR 1806-20
  46. GRB 200501A: Fermi GBM Final Real-time Localization
  47. Trigger 968731: Swift detection of SGR1806-20
  48. Fermi GBM trigger 200429866/609886052 is not a GRB
  49. SGR 1935+2154: MASTER optical observations
  50. Konus-Wind observation of hard X-ray counterpart of the radio burst from SGR 1935+2154
  51. SGR 1935+2154: INTEGRAL hard X-ray counterpart of radio burst
  52. Konus-Wind observation of a very intense bursting activity of SGR 1935+2154
  53. Integral GRB200428.61: Global MASTER-Net observations report
  54. A Forest of Bursts from SGR 1935+2154
  55. SGR 1935+2154: AstroSat CZTI detections
  56. high bursting activity of SGR 1935+2154: CGBM observations
  57. SGR 1935+2154 the Insight-HXMT observation plan
  58. SGR 1935+2154: MAXI/GSC detection
  59. Fermi GBM observation of a bright flare from magnetar SGR 1935+2154
  60. IceCube-200425A: No significant detection in HAWC
  61. Swift detection of multiple bursts from SGR 1935+2154
  62. IceCube-200425A: Upper limits from a search for additional neutrino events in IceCube
  63. IceCube-200425A: Upper limits from Fermi-GBM Observations
  64. Fermi-LAT Gamma-ray Observations of IceCube-200425A
  65. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  66. IceCube-200425A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  67. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  68. GRB 200425A: Swift-BAT refined analysis
  69. IceCube Alert 200425.98: Global MASTER-Net observations report
  70. GRB 200424A: Swift/UVOT Upper Limits
  71. IPN triangulation of GRB 200423A (short)
  72. GRB 200425A: LCO Optical Upper Limits
  73. Swift GRB 200425A: Global MASTER-Net observations report
  74. GRB 200425B: Fermi GBM Final Real-time Localization
  75. GRB 200425A: Swift/UVOT Upper Limits
  76. GRB 200424A: AstroSat CZTI detection
  77. GRB 200425A: Swift-XRT refined Analysis
  78. GRB 200424A: Swift-XRT observations
  79. GRB 200425A: Enhanced Swift-XRT position
  80. GRB 200425A: Swift detection of a burst
  81. GRB 200424A: LCO Optical Upper Limit
  82. GRB 200424A: Swift ToO observations
  83. Konus-Wind observation of GRB 200422A
  84. GRB 200424A: a long GRB detected by INTEGRAL
  85. Fermi GRB 200423A: Global MASTER-Net observations report
  86. GRB 200423A: Fermi GBM Final Real-time Localization
  87. Konus-Wind observation of a bright burst from SGR 1935+2154
  88. GRB 200422A: AstroSat CZTI detection
  89. GRB 200415A correction to GCN 27627 (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  90. GRB 200422A: MASTER optical observations
  91. GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  92. IPN triangulation of GRB 200422A (long/very bright)
  93. IPN Triangulation of a bright burst from SGR 1935+2154
  94. IceCube-200421A: Upper limits from a search for additional neutrino events in IceCube
  95. bright SGR burst detected by CALET Gamma-Ray Burst Monitor
  96. GRB 200415A: ASIM observation
  97. GRB 200410A: Liverpool Telescope First Hour Observations
  98. Fermi-LAT Gamma-ray Observations of IceCube-200421A
  99. IceCube-200421A: No Neutrino Counterpart in ANTARES data
  100. Fermi GRB 200421A: Global MASTER-Net observations report

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