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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 150626A: Swift detection of a burst
  2. Swift Trigger 646423 is GS 1354-645
  3. Trigger 645944: Swift detection of H1745-203
  4. Fermi Gamma-ray Burst Monitor triggers that are not GRBs
  5. V404 Cyg: MASTER Swift, Integral alert observations
  6. Fermi Gamma-ray Burst Monitor triggers bn150622899 and bn150623043 are not GRBs
  7. GRB 150622A: Swift-XRT observations
  8. GRB 150622A: Tiled Swift observations
  9. GRB 150622A: MAXI/GSC detection
  10. Swift Trigger 645340 was Sco X-1
  11. Swift Trigger 645340: a possible GRB
  12. Trigger 645176: Swift detection of V404 Cyg
  13. V404 Cyg: Fermi GBM observations
  14. GRB 150616A: Watcher optical upper limit
  15. Swift triggers again on V404 Cyg
  16. Swift Trigger 644596 is V404 Cyg
  17. Swift Trigger 644520 is V404 Cyg
  18. IBAS trigger 7015 is not a GRB
  19. GRB 150616A: Swift/UVOT Upper Limits
  20. GRB 150616A: Swift-BAT refined analysis
  21. V404 Cyg outburst (Swift trigger 643949 ): TSHAO optical observations
  22. GRB 150616A: Swift-XRT refined Analysis
  23. Konus-Wind observation of Galactic transient V404 Cyg in outburst
  24. GRB 150616A: Enhanced Swift-XRT position
  25. GRB 150616A: Swift detection of a burst
  26. Fermi GBM trigger 150616734 is not a GRB
  27. Fermi GBM trigger 150616594 is not a GRB
  28. V404 Cyg: Swift/UVOT Detection
  29. Fermi Gamma-ray Burst Monitor triggers bn150615791 and bn150615798 are not GRBs
  30. Optical follow-up of Swift trigger on V404 Cyg
  31. GRB 150615A, Swift-BAT refined analysis
  32. Swift trigger 643949 is V404 Cyg
  33. GRB 150615A: Swift-XRT refined Analysis
  34. Fermi GBM trigger 150615574 is not a GRB
  35. GRB 150608A: Swift-XRT follow-up observations
  36. GRB 150615A: Swift/UVOT Detection
  37. GRB 150615A: Enhanced Swift-XRT position
  38. GRB 150615A: Swift detection of a burst
  39. Fermi GBM trigger 150613619 is not a GRB
  40. Fermi GBM trigger 150612648 is not a GRB
  41. GRB 150608A: MITSuME Akeno optical upper limits
  42. Trigger 643078: Swift detection of H1743-322
  43. Konus-Wind observation of GRB 150608A
  44. GRB 150608A: Swift-XRT afterglow detection
  45. Fermi Gamma-ray Burst Monitor trigger 455474712 / 150608698 is not a GRB
  46. GRB150607A: AAO and CrAO optical observations
  47. GRB150607A: Discovery Channel Telescope Optical Observations
  48. GRB 150608A: Tiled Swift observations
  49. GRB 150608A: MAXI/GSC detection
  50. Konus-Wind observation of GRB 150607A
  51. GRB 150607A: Swift-XRT refined Analysis
  52. GRB 150607A: Swift/UVOT Detection
  53. GRB 150607A: NOT optical observations
  54. GRB 150607A: Swift-BAT refined analysis
  55. GRB 150607A: Fermi GBM Detection
  56. GRB 150607A: Enhanced Swift-XRT position
  57. GRB 150607A: Swift detection of a burst with an optical counterpart
  58. GRB 150518A: possible SN observations
  59. Swift trigger 642453 is not an astrophysical source
  60. Swift Trigger 642453: a possible GRB
  61. Konus-Wind observation of GRB 150530A
  62. GRB 150530B: Swift-XRT observations
  63. GRB 150527A: Continued RATIR Observations
  64. Swift Triggers 642296 and 642297 are not GRBs
  65. GRB 150530B: Swift ToO observations
  66. GRB 150530B detected in ground analysis of BAT data
  67. GRB 150530A: RATIR Optical Observations
  68. GRB 150530A: Swift-XRT refined Analysis
  69. GRB 150530A: Swift/UVOT Upper Limits
  70. GRB 150530A: Fermi GBM observation
  71. GRB 150530A: Swift-BAT refined analysis
  72. GRB 150530A: Enhanced Swift-XRT position
  73. GRB 150530A: Swift detection of a burst
  74. Fermi GBM trigger 150529948 is not a GRB
  75. GRB 150513A: Swift-XRT observations
  76. Konus-Wind observation of GRB 150527A
  77. GRB 150527A: Swift-XRT refined Analysis
  78. GRB 150527A: MITSuME Okayama upper limits
  79. GRB 150527A: Swift/UVOT Upper Limits
  80. GRB150527A: REM - NIR afterglow
  81. GRB 150527A: Swift-BAT refined analysis
  82. GRB 150527A: Enhanced Swift-XRT position
  83. GRB 150527A: Fermi GBM observation
  84. GRB 150527A: LCOGT McDonald observations
  85. GRB 150527A: RATIR Afterglow Detection
  86. GRB 150523A: Suzaku WAM observation of the prompt emission
  87. GRB 150527A: Swift detection of a burst
  88. GRB 150523A: Swift ToO observations
  89. GRB 150523A: Swift/UVOT Detection
  90. GRB 150513A: request for X-ray follow up
  91. Konus-Wind observation of GRB 150523A
  92. GRB 150523A: LCOGT FTS afterglow confirmation
  93. GRB 150523A: LCOGT Cerro-Tololo optical afterglow candidate
  94. Confirmation that Swift Trigger 641332 is not astrophysical
  95. GRB 150523A Swift-XRT afterglow detection
  96. GRB 150523B: Swift ToO observations
  97. GRB 150523A: Fermi-LAT detection
  98. GRB 150523A: Fermi GBM detection
  99. Swift trigger 641332 is probably not an astrophysical source
  100. GRB 150518A: Continued RATIR optical observations

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