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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 200410A: Optical upper limit
  2. GRB 200416A: Swift/UVOT Detection
  3. GRB 200416A: Swift-BAT refined analysis
  4. GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
  5. GRB 200415A: MASTER imspection and possible localisation
  6. GRB200412B: GROWTH India detection of afterglow
  7. GRB 200415A: Fermi-LAT localization update
  8. Konus-Wind observation of GRB 200415A (a magnetar Giant Flare in Sculptor Galaxy?)
  9. Improved IPN error box for GRB 200415A (consistent with the Sculptor Galaxy)
  10. GRB 200416A: Swift-XRT refined Analysis
  11. GRB 200412B: continued Tautenburg observations
  12. GRB 200416A: Fermi GBM observation
  13. GRB 200416A: Swift detection of a burst with an optical afterglow
  14. Fermi GRB 200415A: Global MASTER-Net observations report
  15. GRB 200411A: Chandra observations indicative of temporal steepening
  16. GRB 200412A : AstroSat CZTI detection
  17. GRB 200415A: Fermi GBM observation
  18. GRB 200415A: Fermi-LAT detection
  19. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  20. GRB 200410A: CALET Gamma-Ray Burst Monitor detection
  21. GRB 200412B: Mondy optical observations
  22. GRB 200412B: continued Tautenburg observations
  23. Konus-Wind observation of GRB 200412B
  24. GRB 200415A: BALROG localization (Fermi Trigger 608633290 / GRB 200415367)
  25. GRB 200415A: Fermi GBM Final Real-time Localization
  26. GRB 200410A: Swift-BAT refined analysis
  27. Konus-Wind observation of GRB 200412A
  28. GRB 200412B: MITSuME Akeno optical observation
  29. GRB 200412B: Tautenburg observations
  30. GRB 200412B: contunued AbAO optical observations
  31. GRB 200411A: ATCA 5/9 GHz radio observations
  32. GRB 200412B: CALET Gamma-Ray Burst Monitor detection
  33. GRB 200412B: Xinglong TNT optical observations
  34. GRB 200412B: SAO RAS observations of OT
  35. IceCube-200410A: No significant detection in HAWC
  36. GRB 200405B: Further Swift-XRT observations
  37. GRB 200412B: Tautenburg observations
  38. GRB 200412B: AbAO optical observations
  39. GRB 200412B: Insight-HXMT/HE detection
  40. GRB 200412B: Optical afterglow detection with 1.3m DFOT
  41. GRB 200412B : AstroSat CZTI detection
  42. IceCube-200410A : Upper limits from Insight-HXMT/HE observations
  43. GRB 200412B: Swift-XRT afterglow detection
  44. IPN triangulation of GRB 200412A
  45. Fermi GRB 200412A: Global MASTER-Net observations report
  46. GRB 200412B: Fermi GBM detection
  47. GRB 200412B: Fermi-LAT detection
  48. GRB 200412B: MASTER-Amur Optical Couterpart in Gagarin day!
  49. GRB 200412B: MASTER Optical Couterpart in Gagarin day!
  50. Konus-Wind observation of a bright burst from SGR 1935+2154
  51. Correction to GCN 27551 - Swift is observing GRB 200412*B*
  52. IceCube-200410A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 200412B: Tiled Swift observations
  54. GRB 200412A: Fermi GBM detection
  55. Fermi GRB 200412B: Global MASTER-Net observations report
  56. GRB 200412B: BALROG localization (Fermi Trigger 608375325 / GRB 200412381)
  57. GRB 200412B: Fermi GBM Final Real-time Localization
  58. GRB 200412A: BALROG localization (Fermi Trigger 608367436 / GRB 200412290)
  59. GRB 200411A: Swift-BAT refined analysis
  60. Fermi-LAT Gamma-ray Observations of IceCube-200410A
  61. GRB 200411A: Fermi GBM observation
  62. Swift GRB 200411A: Global MASTER-Net observations report
  63. IceCube-200410A: Upper limits from Fermi-GBM Observations
  64. GRB 200411A: Swift-XRT refined Analysis
  65. GRB 200411A: Swift/UVOT Upper Limits
  66. GRB 200411A: Enhanced Swift-XRT position
  67. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  68. GRB 200411A: Swift detection of a short burst
  69. GRB 200411A: Fermi GBM Final Real-time Localization
  70. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  71. IceCube Alert 200410.97: Global MASTER-Net observations report
  72. GRB 200410A: Swift/UVOT Detection
  73. SGR 1935+2154: Fermi GBM observation
  74. Baksan Neutrino Observatory Alert 200410.82: Global MASTER-Net observations report
  75. Fermi trigger No 608204639: Global MASTER-Net observations report
  76. Baksan Neutrino Observatory Alert 200409.81: Global MASTER-Net observations report
  77. IPN Triangulation of a bright burst from SGR 1935+2154
  78. LIGO/Virgo S200225q: Swift XRT observations, 1 X-ray sources
  79. Konus-Wind observation of GRB 200327A
  80. LIGO/Virgo S200224ca: Swift XRT observations, 8 X-ray sources
  81. GRB 200410A: Swift-XRT refined Analysis
  82. GRB 200410A: Enhanced Swift-XRT position
  83. GRB 200409A: No detection of radio emission 5 hours post-burst
  84. GRB 200410A: Ondrejov D50 afterglow confirmation
  85. GRB 200409A: Swift-BAT refined analysis
  86. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  87. Swift GRB200410.10: Global MASTER-Net observations report
  88. GRB 200405B: ATCA follow-up and ASKAP limits on pre-burst radio emission
  89. Baksan Neutrino Observatory Alert 200408.26: Global MASTER-Net observations report
  90. Fermi GBM Sub-Threshold Detection of GRB 200409A
  91. Baksan Neutrino Observatory Alert 200409.23: Global MASTER-Net observations report
  92. Swift GRB 200409A: Global MASTER-Net observations report
  93. GRB 200409A: Swift-XRT refined Analysis
  94. GRB 200409A: Enhanced Swift-XRT position
  95. GRB 200409A: Swift detection of a burst with an optical counterpart
  96. Fermi GRB 200407A: Global MASTER-Net observations report
  97. Fermi GRB 200407B: Global MASTER-Net observations report
  98. IPN triangulation of GRB 200407A (short)
  99. IPN triangulation of GRB 200405B (short)
  100. Baksan Neutrino Observatory Alert 200406.3: Global MASTER-Net observations report

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