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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 181030A: Enhanced Swift-XRT position
  2. GRB 181030A: SAO RAS optical observations
  3. GRB 181030A: Swift detection of a burst with a possible optical counterpart
  4. IPN Triangulation of GRB 181028A (long)
  5. GRB 181028A: Fermi GBM observation
  6. GRB 181028A: Fermi-LAT detection
  7. GRB 181027A: Fermi GBM detection
  8. GRB 181027A: Swift-BAT refined analysis
  9. GRB 181027A: Swift detection of a burst
  10. IceCube-181023A: HAWC follow-up
  11. IceCube-181023A: MASTER Net optical alert and follow up observations
  12. Search for counterparts to IceCube-181023A with IceCube
  13. GRB 180728B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 554505003)
  14. Fermi-LAT Gamma-ray Observations of IceCube-181023A
  15. GRB 181023A: Swift-BAT refined analysis
  16. GRB 181023A: Swift/UVOT Upper Limits
  17. IceCube-181023A - IceCube observation of a high-energy neutrino candidate event
  18. GRB 181022A: Swift-XRT refined Analysis
  19. GRB 181023A: Swift-XRT refined Analysis
  20. GRB 181022A: MITSuME Akeno optical upper limits
  21. GRB 181022A: GROND upper limits
  22. GRB 181022A: LCO Sutherland observations
  23. GRB 181023A: Enhanced Swift-XRT position
  24. GRB 181023A: KAIT Optical Upper Limit
  25. GRB 181022A: Swift/UVOT Upper Limits
  26. GRB 181023A: Swift detection of a burst
  27. GRB 181022A: Swift-BAT refined analysis
  28. GRB 181022A: Swift detection of a burst
  29. Konus-Wind observation of GRB 181020A
  30. GRB 181020A: REM detection
  31. Baksan Neutrino BNO 181021: Global MASTER-net Optical Follow-up Observations
  32. GRB 181020A: Swift/UVOT Detection
  33. GRB 181020A: Global MASTER Net OT observations
  34. GRB 181020A: LCO Cerro Tololo observations
  35. GRB 181020A: Swift-BAT refined analysis
  36. GRB 181020A: VLT/X-shooter spectroscopy and redshift
  37. GRB 181018A: Insight-HXMT/HE detection
  38. GRB 181017A: Insight-HXMT/HE detection
  39. GRB 181020A: Swift-XRT refined Analysis
  40. GRB 181020A: Fermi GBM detection
  41. GRB 181020A: Enhanced Swift-XRT position
  42. GRB 181020A: Fermi-LAT detection
  43. GRB 181020A: Swift detection of a burst with an optical counterpart
  44. FRB 181016: MASTER optical inspection of the Fast Radio Burst error box
  45. GRB 181014A: Insight-HXMT/HE detection
  46. Fermi GBM Observation of IceCube-181014A
  47. GRB 181011A: MITSuME Akeno and Okayama optical upper limits
  48. Trigger 867343: Swift detection of SGR1806-20
  49. GRB 181016A: Swift-BAT refined analysis
  50. GRB 181016A: Swift detection of a burst
  51. GRB 181013A: AbAO optical upper limit
  52. Search for counterparts to IceCube-181014A with IceCube
  53. Fermi-LAT Gamma-ray Observations of IceCube-181014A
  54. IceCube-181014A - IceCube observation of a high-energy neutrino candidate event
  55. Trigger 866993: Swift detection of SGR1806-20
  56. GRB 181013A: Swift/UVOT Upper Limits
  57. GRB 181013A: Swift-BAT refined analysis
  58. GRB 181013A: Swift-XRT afterglow detection
  59. GRB 181013A: Global MASTER Net optical observations
  60. GRB 181013A: Swift detection of a probable burst
  61. Swift Trigger 866757: is probably not a GRB
  62. GRB 181011A: Global MASTER Net optical inspection
  63. GRB 181011A: CALET Gamma-Ray Burst Monitor detection
  64. IPN Triangulation of GRB 181011A (long)
  65. GRB 181011A: MAXI/GSC detection
  66. GROND afterglow detection of GRB 181010A
  67. GRB180913A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 558557292)
  68. GRB 181010A: REM optical and NIR afterglow detection
  69. GRB 181008B: Global MASTER Net optical inspection
  70. GRB 181010A: Swift-BAT refined analysis
  71. GRB 181010A: Fermi GBM observation
  72. GRB 181010A: ePESSTO NTT optical observations
  73. IPN Triangulation of GRB 181008B (long)
  74. GRB 181010A: Swift/UVOT Detection
  75. GRB 181010A: Swift-XRT refined Analysis
  76. GRB 181010A: VLT/X-shooter redshift
  77. GRB 181008A: Insight-HXMT/HE detection
  78. GRB 181010A: Enhanced Swift-XRT position
  79. GRB 181010A: RATIR Optical and NIR Afterglow Detection
  80. GRB 181010A: LCO Cerro Tololo observations
  81. GRB 181010A: MASTER-Argentina OT detection
  82. GRB 181010A: Swift detection of a burst with an optical counterpart
  83. GRB 181002A: Mondy optical upper limit
  84. GRB 181003A: RATIR Optical and NIR Observations
  85. GRB 181003A: Swift-BAT refined analysis
  86. GRB 181003A: Swift-XRT afterglow detection
  87. GRB 180925A: Astrosat CZTI detection
  88. GRB 181003A: Swift/UVOT Upper Limits
  89. GRB 180930A: TSHAO optical upper limit
  90. GRB 181002A: Swift-XRT refined Analysis
  91. GRB 181003A: LCO Cerro Tololo observations
  92. GRB 181003A: MASTER optical observation
  93. GRB181002A: GOTO optical limits
  94. GRB 181002A: Swift/UVOT Upper Limits
  95. GRB 181003A: Swift-XRT observations
  96. GRB 181003A: Swift detection of a burst
  97. GRB 181002A: Swift-BAT refined analysis
  98. GRB 181002A: MASTER optical observation
  99. GRB 181002A: Enhanced Swift-XRT position
  100. Konus-Wind observation of GRB 180925A

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