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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. Fermi GBM triggers 544628550/180405571, 544542853/180404579, 544531428/180404447 are not GRBs
  2. GRB 180404A: Swift/UVOT Detection
  3. GRB 180404A: LCO FTS observations
  4. GRB 180404A: Swift-XRT refined Analysis
  5. GRB 180404B: Swift-BAT refined analysis
  6. GRB 180402A: Fermi GBM refined spectral analysis
  7. GRB 180404A: Swift-BAT refined analysis
  8. GRB 180404B: Swift-XRT refined Analysis
  9. GRB 180404B: Fermi GBM observation
  10. GRB 180404B: MASTER-OAFA OT observation
  11. Fermi GBM triggers 544440014/180403389 and 544451446/180403521 are not GRBs
  12. GRB 180404B: Enhanced Swift-XRT position
  13. GRB 180404A: MASTER-OAFA OT observation
  14. GRB 180404A: Enhanced Swift-XRT position
  15. GRB 180404A: VLT/X-shooter redshift
  16. GRB 180404B: Swift detection of a burst with an optical counterpart
  17. GRB 180404A: Swift detection of a burst with an optical afterglow
  18. Konus-Wind observation of GRB 180402A
  19. GRB 180402A: Swift/UVOT Upper Limits
  20. GRB 180402A: Swift-XRT refined Analysis
  21. GRB 180402A: Fermi GBM detection
  22. GRB 180402A, Swift-BAT refined analysis
  23. GRB 180402A: KAIT Optical Upper Limit
  24. GRB 180402A: RATIR Upper Limits
  25. GRB 180402A: LCO McDonald observations
  26. GRB 180402A: Swift detection of a possibly short burst
  27. GRB 180331B: Swift/UVOT Upper Limits
  28. GRB 180331B: Swift-XRT refined Analysis
  29. GRB 180331B: AbAO optical observations
  30. GRB 180331B: Swift-BAT refined analysis
  31. GRB 180331B: Enhanced Swift-XRT position
  32. GRB 180331A: Swift-BAT refined analysis
  33. GRB 180331B: Swift detection of a burst
  34. GRB 180331A: Swift-XRT refined Analysis
  35. GRB 180329B: LCO FTS observations
  36. GRB 180331A: Swift/UVOT Upper Limits
  37. GRB 180331A: Enhanced Swift-XRT position
  38. GRB 180331A: Swift detection of a burst
  39. GRB 180329B: VLT/X-shooter spectroscopic observations
  40. GRB 180329B: Swift-BAT refined analysis
  41. GRB 180329B: Swift/UVOT Detection
  42. GRB 180329B: RATIR Optical Observations
  43. Swift Trigger 819863 is not a GRB
  44. GRB 180329B: NOT optical afterglow detection
  45. GRB 180329A: Swift-BAT refined analysis
  46. GRB 180329B: Swift-XRT refined Analysis
  47. GRB 180329B: Enhanced Swift-XRT position
  48. GRB 180329B: Swift detection of a burst with an optical afterglow
  49. GRB180325A: AstroSat CZTI detection
  50. Swift Trigger 819301: possible GRB 180329A
  51. GRB 180325A: VLT/X-shooter spectroscopic observations
  52. Konus-Wind observation of GRB 180318A
  53. Konus-Wind observation of GRB 180326A
  54. Konus-Wind observation of GRB 180317A
  55. GRB 180325A: further NOT observations
  56. IPN Triangulation of GRB 180326A (long)
  57. GRB 180325A: Swift/UVOT Detection
  58. Konus-Wind observation of GRB 180316A
  59. Konus-Wind observation of GRB 180324A
  60. Konus-Wind observation of GRB 180325A
  61. GRB 180325A, Swift-BAT refined analysis
  62. GRB 180325A: GROND observations
  63. GRB 180325A: Global MASTER-Net OT prompt observations
  64. GRB 180325A: TAROT Calern observatory optical observations
  65. GRB 180325A: D50 early optical follow-up
  66. GRB 180325A: Swift-XRT refined Analysis
  67. GRB 180325A: Enhanced Swift-XRT position
  68. GRB 180325A: Optical Photometry with SLKT
  69. GRB 180325A: RATIR Optical Observations
  70. GRB 180325A: prompt REM optical/NIR detection
  71. GRB 180325A: NOT redshift
  72. GRB 180325A: prompt LT observations
  73. GRB 180324A, Swift-BAT refined analysis
  74. GRB 180325A: Swift detection of a burst with an optical counterpart
  75. GRB 180324A: Swift/UVOT Upper Limits
  76. GRB 180324A: Swift-XRT refined Analysis
  77. GRB 180324A: Enhanced Swift-XRT position
  78. GRB 180324A: RATIR Optical Observations and Possible Afterglow Detection
  79. GRB 180324A: KAIT Optical Upper Limit
  80. GRB 180324A: Prompt enhanced Swift-XRT position
  81. GRB 180324A: Swift detection of a burst
  82. IBAS Alert n. 8033: Not a GRB
  83. IPN Triangulation of GRB 180318A (long)
  84. IPN Triangulation of GRB 180317A (short/hard)
  85. IBAS Alert n. 8032: Not a GRB
  86. GRB 180316A: RATIR Optical Observations
  87. GRB 180316A: MITSuME Akeno optical upper limits
  88. GRB 180316A: MITSuME Okayama optical upper limits
  89. GRB 180316A: TSHAO optical observations
  90. GRB 180314A: AstroSat CZTI detection
  91. GRB 180316A: RATIR Optical Observations, Possible Re-brightening
  92. Konus-Wind observation of GRB 180314A
  93. GRB 180316A: Swift-BAT refined analysis
  94. GRB 180316A: Swift-XRT refined Analysis
  95. GRB 180316A: Swift/UVOT Detection
  96. GRB 180316A: RATIR Optical Observations
  97. GRB 180316A: Enhanced Swift-XRT position
  98. GRB 180316A: LCO Cerro Tololo observations
  99. GRB 180314A: MITSuME Okayama optical upper limits
  100. GROND observations of GRB 180316A

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