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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. No optical bursts detected from SGR J1935+2154 by 24 fps observations with Tomo-e Gozen
  2. GRB 200502A: Fermi GBM Final Real-time Localization
  3. GRB 200424A: Swift-XRT afterglow detection
  4. Insight-HXMT X-ray and hard X-ray detection of the double peaks of the Fast Radio Burst from SGR 1935+2154
  5. Fermi GBM observation of a flare from the magnetar SGR 1806-20
  6. GRB 200501A: Fermi GBM Final Real-time Localization
  7. Trigger 968731: Swift detection of SGR1806-20
  8. Fermi GBM trigger 200429866/609886052 is not a GRB
  9. SGR 1935+2154: MASTER optical observations
  10. Konus-Wind observation of hard X-ray counterpart of the radio burst from SGR 1935+2154
  11. SGR 1935+2154: INTEGRAL hard X-ray counterpart of radio burst
  12. Konus-Wind observation of a very intense bursting activity of SGR 1935+2154
  13. Integral GRB200428.61: Global MASTER-Net observations report
  14. A Forest of Bursts from SGR 1935+2154
  15. SGR 1935+2154: AstroSat CZTI detections
  16. high bursting activity of SGR 1935+2154: CGBM observations
  17. SGR 1935+2154 the Insight-HXMT observation plan
  18. SGR 1935+2154: MAXI/GSC detection
  19. Fermi GBM observation of a bright flare from magnetar SGR 1935+2154
  20. IceCube-200425A: No significant detection in HAWC
  21. Swift detection of multiple bursts from SGR 1935+2154
  22. IceCube-200425A: Upper limits from a search for additional neutrino events in IceCube
  23. IceCube-200425A: Upper limits from Fermi-GBM Observations
  24. Fermi-LAT Gamma-ray Observations of IceCube-200425A
  25. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  26. IceCube-200425A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  27. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  28. GRB 200425A: Swift-BAT refined analysis
  29. IceCube Alert 200425.98: Global MASTER-Net observations report
  30. GRB 200424A: Swift/UVOT Upper Limits
  31. IPN triangulation of GRB 200423A (short)
  32. GRB 200425A: LCO Optical Upper Limits
  33. Swift GRB 200425A: Global MASTER-Net observations report
  34. GRB 200425B: Fermi GBM Final Real-time Localization
  35. GRB 200425A: Swift/UVOT Upper Limits
  36. GRB 200424A: AstroSat CZTI detection
  37. GRB 200425A: Swift-XRT refined Analysis
  38. GRB 200424A: Swift-XRT observations
  39. GRB 200425A: Enhanced Swift-XRT position
  40. GRB 200425A: Swift detection of a burst
  41. GRB 200424A: LCO Optical Upper Limit
  42. GRB 200424A: Swift ToO observations
  43. Konus-Wind observation of GRB 200422A
  44. GRB 200424A: a long GRB detected by INTEGRAL
  45. Fermi GRB 200423A: Global MASTER-Net observations report
  46. GRB 200423A: Fermi GBM Final Real-time Localization
  47. Konus-Wind observation of a bright burst from SGR 1935+2154
  48. GRB 200422A: AstroSat CZTI detection
  49. GRB 200415A correction to GCN 27627 (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  50. GRB 200422A: MASTER optical observations
  51. GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  52. IPN triangulation of GRB 200422A (long/very bright)
  53. IPN Triangulation of a bright burst from SGR 1935+2154
  54. IceCube-200421A: Upper limits from a search for additional neutrino events in IceCube
  55. bright SGR burst detected by CALET Gamma-Ray Burst Monitor
  56. GRB 200415A: ASIM observation
  57. GRB 200410A: Liverpool Telescope First Hour Observations
  58. Fermi-LAT Gamma-ray Observations of IceCube-200421A
  59. IceCube-200421A: No Neutrino Counterpart in ANTARES data
  60. Fermi GRB 200421A: Global MASTER-Net observations report
  61. IceCube-200421A: No significant detection in HAWC
  62. GRB 200421A: Fermi GBM Final Real-time Localization
  63. IceCube-200421A: not observable by Fermi-GBM
  64. IceCube Alert 200421.02: Global MASTER-Net observations report
  65. IceCube-200421A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  66. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  67. IceCube Alert 200420.97: Global MASTER-Net observations report
  68. GRB 200412B: continued Mondy and Terskol optical observations
  69. GRB 200420: Fermi GBM Final Localization Correction
  70. Fermi GRB 200420A: Global MASTER-Net observations report
  71. GRB 200420A: Fermi GBM Final Real-time Localization
  72. Fermi trigger No 608935505: Global MASTER-Net observations report
  73. GRB 200412B: continued Terskol optical observations
  74. GRB 200412B: continued AbAO, Mondy, TSHAO, Terskol optical observations
  75. GRB 200410A: Optical upper limit
  76. GRB 200416A: Swift/UVOT Detection
  77. GRB 200416A: Swift-BAT refined analysis
  78. GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
  79. GRB 200415A: MASTER imspection and possible localisation
  80. GRB200412B: GROWTH India detection of afterglow
  81. GRB 200415A: Fermi-LAT localization update
  82. Konus-Wind observation of GRB 200415A (a magnetar Giant Flare in Sculptor Galaxy?)
  83. Improved IPN error box for GRB 200415A (consistent with the Sculptor Galaxy)
  84. GRB 200416A: Swift-XRT refined Analysis
  85. GRB 200412B: continued Tautenburg observations
  86. GRB 200416A: Fermi GBM observation
  87. GRB 200416A: Swift detection of a burst with an optical afterglow
  88. Fermi GRB 200415A: Global MASTER-Net observations report
  89. GRB 200411A: Chandra observations indicative of temporal steepening
  90. GRB 200412A : AstroSat CZTI detection
  91. GRB 200415A: Fermi GBM observation
  92. GRB 200415A: Fermi-LAT detection
  93. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  94. GRB 200410A: CALET Gamma-Ray Burst Monitor detection
  95. GRB 200412B: Mondy optical observations
  96. GRB 200412B: continued Tautenburg observations
  97. Konus-Wind observation of GRB 200412B
  98. GRB 200415A: BALROG localization (Fermi Trigger 608633290 / GRB 200415367)
  99. GRB 200415A: Fermi GBM Final Real-time Localization
  100. GRB 200410A: Swift-BAT refined analysis

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