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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 190203A: Liverpool Telescope near-IR observations
  2. Konus-Wind observation of GRB 190203A
  3. GRB 190203A: Swift-XRT refined Analysis
  4. GRB 190204A: Swift-XRT refined Analysis
  5. GRB 190204A: AstroSat CZTI detection
  6. Swift Trigger 887541: MASTER inspect
  7. GRB 190204A: MAXI/GSC detection
  8. GRB 190202A: R and I band observation from HCT
  9. GRB 190204A: Swift detection of a burst with a possible optical counterpart
  10. Swift Trigger 887541: MASTER optical observation
  11. GRB 190203A: MASTER OT detection
  12. Swift Trigger 887541: Swift detection of Swift J1728.9-3613
  13. GRB 190203A: Enhanced Swift-XRT position
  14. GRB 190203A: SAO RAS optical observations, afterglow fading
  15. GRB 190203A: Koshka Zeiss-1000 optical upper limit
  16. GRB 190203A: Swift detection of a burst with an optical counterpart
  17. GRB 190202A: SAO RAS optical observations
  18. GRB 190202A: TSHAO optical observations
  19. GRB 190202A: NOT optical observations
  20. GRB 190202A: McDonald 0.8-m telescope optical observation
  21. GRB 190202A: Swift-XRT refined Analysis
  22. GRB 190202A: LCO-CTIO optical observations
  23. GRB 190202A: Fermi GBM observation
  24. Fermi GBM trigger 570825115/190202772 is not a GRB
  25. GRB 190202A, Swift-BAT refined analysis
  26. GRB 190202A: AGILE ratemeters detection
  27. GRB 190202A: Swift/UVOT Detection
  28. GRB 190202A: GOTO optical observations
  29. GRB 190202A: Enhanced Swift-XRT position
  30. GRB 190202A: Koshka Zeiss-1000 optical observations
  31. GRB 190202A: Swift detection of a burst with an optical counterpart
  32. Fermi GBM trigger 570716645/190201517 is not a GRB
  33. GRB 190131A: Insight-HXMT/HE detection
  34. GRB 190131A: AstroSat CZTI detection
  35. GRB 190126A: AstroSat CZTI detection
  36. Fermi GBM trigger 570659556/190131856 is not a GRB
  37. GRB 190129B: Insight-HXMT/HE detection
  38. GRB 190114C: JCMT SCUBA-2 sub-mm observations
  39. Improved IPN error box for GRB 190129B
  40. GRB 190129B: GOTO optical observations
  41. GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
  42. GRB 190129B: Swift/UVOT Upper Limits
  43. GRB 190129B: ePESSTO NTT optical observations
  44. GRB 190129B: AstroSat CZTI detection
  45. GRB 190129B: MASTER Global Robotic Net optical observation
  46. GRB 190129A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 190129B: GROND possible host candidate
  48. GRB 190129B: Swift-XRT candidate afterglow detection
  49. GRB 190129B: Tiled Swift observations
  50. Fermi GBM Observations of IceCube-190124A
  51. GRB 190129A: Fermi GBM detection
  52. Konus-Wind observation of extremely bright GRB 190129B
  53. IPN Triangulation of GRB 190129B (long/extremely bright)
  54. INTEGRAL observation of IceCube-190124A
  55. GRB 190129A: MAXI/GSC detection
  56. Trigger 886496: Another Swift trigger on MAXI J1348-630
  57. Swift Trigger 886157: MASTER optical observation
  58. Trigger 886486: Swift detection of MAXI J1631-479
  59. Trigger 886266: Another Swift trigger on MAXI J1348-630
  60. Swift Trigger 886157: Swift detection of a new transient Swift J1728.9-3613
  61. INTEGRAL triggers from 8205 to 8211 are due to MAXI J1348-630, NOT to a GRB
  62. GRB 190114C: Optical follow-up from HCT
  63. Swift Trigger 885960: A third Swift trigger on MAXI J1348-630
  64. Trigger 885845: A second Swift trigger on MAXI J1348-630
  65. Trigger 885807: Swift detection of MAXI J1348-630
  66. Search for counterparts to IceCube-190124A with IceCube
  67. Search for counterpart to IceCube-190124A with ANTARES
  68. GRB 190117A: AstroSat CZTI detection
  69. GRB 190122B: AstroSat CZTI detection
  70. Fermi-LAT Gamma-ray Observations of IceCube-190124A
  71. GRB 190123A: IKI-GRB-FuN optical upper limit
  72. GRB 190123A: NEXT-0.6m optical limit
  73. GRB 190114C: CHILESCOPE optical observations
  74. GRB 190123A: AROMA-N Optical Observation
  75. IceCube-190124A - IceCube observation of a high-energy neutrino candidate event
  76. GRB 190123A: Swift/UVOT Upper Limits
  77. Konus-Wind observation of GRB 190122A
  78. Konus-Wind of observation of GRB 190117A
  79. GRB 190123A: COATLI Optical Observations
  80. GRB 190123A: Swift-BAT refined analysis
  81. GRB 190121A: CALET Gamma-Ray Burst Monitor detection of a short burst
  82. GRB190123A: MITSuME Akeno optical upper limits
  83. GRB 190123A: GMG observational limit
  84. Trigger 885456: Swift detection of MAXI J1631-479
  85. GRB 190123A: Swift-XRT refined Analysis
  86. GRB 190123A: GOTO optical limit
  87. GRB 190123A: Fermi GBM observation
  88. GRB 190123A: BOOTES-4/MET optical limit
  89. GRB 190123A: Enhanced Swift-XRT position
  90. GRB 190123A: MASTER Global Robotic Net optical observation
  91. GRB 190123A: Swift detection of a burst
  92. GRB 190122A: Fermi GBM observation
  93. GRB 190122A: Fermi-LAT detection
  94. GRB 190114C: RTT150 optical observations
  95. IPN Triangulation of GRB 190118A (long)
  96. IPN Triangulation of GRB 190117A (long)
  97. Trigger 884906: Swift detection of MAXI J1631-479
  98. GRB 190114C: GMRT detection at 1.26GHz
  99. Swift ToO Instructions Update
  100. GRB 190114C: MeerKAT radio observation

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