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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 190326B: AstroSat CZTI detection
  2. GRB 190331B: Swift observations of a ground-detected burst
  3. Fermi-LAT Gamma-ray Observations of IceCube-190331A
  4. Search for additional neutrino events from the direction of IceCube-190331A with IceCube
  5. GRB 190401A: Insight-HXMT/HE detection
  6. GRB 190331C: Insight-HXMT/HE detection
  7. GRB 190331A: Insight-HXMT/HE detection
  8. GRB 190330A: Insight-HXMT/HE detection
  9. IceCube-190331A: MASTER optical follow-up observations
  10. GRB 190329A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 190331A: Fermi GBM detection
  12. GRB 190331B: Swift ToO observations
  13. GRB 190331A, Swift-BAT refined analysis
  14. IPN Triangulation of GRB 190329A (long/bright)
  15. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  16. GRB 190331A: Swift detection of a burst
  17. Fermi Trigger 575656777 / GRB 190330694 / GRB 190330A: BALROG localization
  18. GRB 190323A: AstroSat CZTI detection
  19. MAGIC follow-up of the X-ray flares of LS I +61�303 dete
  20. GRB 190326A: 2.2m CAHA telescope optical limit
  21. Swift Trigger 895503 is not a GRB
  22. Swift Trigger 895479: Detection of GRO J2058+42
  23. GRB 190326A: Swift-BAT refined analysis - a soft-short GRB or an SGR
  24. GRB 190326B: Insight-HXMT/HE detection
  25. GRB 190326A: Insight-HXMT/HE detection
  26. Swift Trigger 895257: Detection of GRO J2058+42 in outburst
  27. GRB 190326A: MITSuME Okayama optical upper limits
  28. Konus-Wind observation of GRB 190324A
  29. GRB 190324A: Swift/UVOT Observations
  30. GRB 190326B: Fermi GBM detection
  31. GRB 190324B: Insight-HXMT/HE detection
  32. GRB 190324A: Insight-HXMT/HE detection
  33. Fermi Trigger 575278303 / GRB 190326314 / GRB190326B: BALROG localization
  34. GRB 190326A: Swift detection of a short burst
  35. Fermi Trigger 575251142 / GRB 190325999 / GRB 190325A: BALROG localization
  36. GRB 190324A: Swift-BAT refined analysis
  37. GRB 190324A: CALET Gamma-Ray Burst Monitor detection
  38. GRB 190323A: Insight-HXMT/HE detection
  39. GRB 190324A: Swift-XRT refined Analysis
  40. GRB190324A: MASTER OT observations
  41. GRB 190324A: Fermi GBM observation
  42. GRB 190324A: Enhanced Swift-XRT position
  43. Further Chandra observations of GW170817 ~581-583 days since merger
  44. GRB 190324A: VLT/X-shooter redshift
  45. GRB 190321A: Insight-HXMT/HE detection
  46. GRB 190324A: Swift-XRT observations
  47. GRB 190324A: Swift/UVOT afterglow candidate
  48. SWIFT GRB190324.95 Global MASTER-Net observations report
  49. Fermi Trigger 575160247 / GRB 190324947: BALROG localization
  50. GRB 190324A: Swift detection of a burst
  51. Fermi Trigger 575108474 / GRB 190324348: BALROG localization
  52. SWIFT GRB190323.85 Global MASTER-Net observations report
  53. Fermi Trigger 575067924 / GRB 190323879: BALROG localization
  54. Swift detection of LS I +61 303
  55. Fermi Trigger 575018216 / GRB 190323303: BALROG localization
  56. Correction: Chandra observations of GW170817 ~581 days since merger
  57. Chandra observations of GW170817 ~581 days since merger
  58. Swift Trigger 894268: Detection of GRO J2058+42 in outburst
  59. Fermi Trigger 574850558 / GRB 190321363: BALROG localization
  60. GRB 190114C: photometric detection of a SN component
  61. GRB 190320A: Swift/UVOT Upper Limits
  62. GRB 190320A: Swift-XRT refined Analysis
  63. GRB 190320A: Swift-BAT refined analysis
  64. GRB190320A: MASTER GRB counterpart decay
  65. GRB 190320A: Fermi GBM observation
  66. GRB 190320A: Enhanced Swift-XRT position
  67. GRB190320A: MASTER OT detection
  68. SWIFT GRB190320.05 Global MASTER-Net observations report
  69. GRB 190320A: Swift-XRT observations
  70. GRB 190320A: Swift detection of a burst
  71. GRB 190315A: AstroSat CZTI detection
  72. Fermi Trigger 574678842 / GRB 190319375: BALROG localization
  73. Fermi Trigger 574676902 / GRB 190319353: BALROG localization
  74. Fermi Trigger 574345067 / GRB 190315512: BALROG localization
  75. GRB190311A: MITSuME Akeno optical observation
  76. Fermi trigger 574140965 / GRB190313.15: MASTER Global Robotic Net optical observation
  77. GRB 190311A: OSN optical afterglow detection
  78. GRB 190311A: Swift/UVOT Detection
  79. GRB 190311A: Mondy optical observations
  80. GRB 190311A: Liverpool Telescope observations
  81. GRB 190311A: NOT optical counterpart
  82. GRB 190311A: Swift-BAT refined analysis
  83. GRB190305A: MASTER Global Robotic Net optical observation
  84. GRB190311A: OAO observations
  85. GRB 190311A: Mondy optical observations
  86. Fermi Trigger 574080135 / GRB 190312446: BALROG localization
  87. Improved Fermi/GBM GRB localizations
  88. [Hxmt-ba]GRB 190310A: Insight-HXMT/HE detection
  89. GRB 190311A: GMG observation
  90. GRB 190311A: Fermi GBM observation
  91. GRB 190311A: Swift-XRT refined Analysis
  92. GRB 190311A: TSHAO optical observations
  93. GRB 190311A: Enhanced Swift-XRT position
  94. GRB190311A: MASTER Global Robotic Net OT optical observation
  95. GRB 190311A: NEXT-0.6m optical afterglow detection
  96. GRB 190311A: Mondy optical observations
  97. GRB 190311A: Swift detection of a burst with optical counterpart
  98. GRB 190305A: Swift-XRT afterglow detection
  99. GRB 190305A: CALET Gamma-Ray Burst Monitor detection
  100. Konus-Wind observation of GRB 190304A

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