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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 090813: Enhanced Swift-XRT position
  2. GRB 090813: Liverpool Telescope afterglow confirmation
  3. GRB 090813: P60 Optical Afterglow Confirmation
  4. GRB 090813: optical candidate from 1.23m CAHA telescope
  5. GRB 090813: Swift detection of a burst
  6. GRB 090812: WIRO NIR upper limit
  7. GRB 090812: Faulkes Telescope South Continued Optical Monitoring
  8. GRB 090812: RAPTOR detections during the burst
  9. GRB 090812: Swift XRT refined analysis
  10. GRB 090812, RIMOTS optical upper limits
  11. GRB 090812 Swift-BAT Refined Analysis
  12. GRB090812: Swift/UVOT observations
  13. GRB 090812: GROND Observations of the Optical/NIR Afterglow
  14. GRB 090812: Enhanced Swift-XRT position
  15. GRB 090812 VLT redshift
  16. GRB 090812: Liverpool Telescope afterglow confirmation
  17. GRB 090812: P60 Confirmation of Optical Afterglow
  18. GRB 090812: Swift detection of a burst with an optical counterpart
  19. GRB 090807B: Fermi GBM detection
  20. GRB 090809: Further NOT optical observations
  21. VLA radio upper limit on GRB 090809
  22. GRB 090621B: MAGIC telescope GeV observation
  23. GRB 090621A: MAGIC telescope GeV observation
  24. GRB 090809: WHT observations
  25. GRB 090809 X-shooter redshift
  26. GRB 090809B: Fermi GBM detection
  27. GRB 090809: Swift-XRT refined analysis
  28. GRB090809: Swift/UVOT observations
  29. GRB 090809: Enhanced Swift-XRT position
  30. GRB 090809: Swift-BAT refined analysis
  31. GRB 090809: afterglow confirmation at the NOT
  32. GRB 090809: Swift detection of a burst with a possible optical counterpart
  33. GRB 090807: Liverpool Telescope observations
  34. GRB 090807: MITSuME optical upper limit
  35. GRB 090807: Swift/UVOT Upper Limits
  36. GRB 090807: Swift-XRT refined analysis
  37. GRB 090807, Swift-BAT refined analysis
  38. GRB 090807: Enhanced Swift-XRT position
  39. GRB 090807, RIMOTS optical upper limits
  40. GRB 090807: Swift detection of a burst
  41. Fermi Gamma-ray Burst Monitor trigger 271275771 is not a GRB
  42. GRB 090802B: Fermi GBM detection
  43. IPN Triangulation and Konus-Wind observaions of GRB090727B
  44. GRB 090802: Fermi GBM detection
  45. GRB 090726: optical observation
  46. Swift-BAT trigger 358760 is most likely not a GRB
  47. Swift trigger 358760 is probably a noise event
  48. GRB 090717A: Suzaku WAM observation of the prompt emission
  49. GRB 090709A : Quick look analysis of the Suzaku observation
  50. GRB 090728: Swift-BAT refined analysis
  51. GRB 090727: GRT Optical Observation
  52. GRB 090728: Swift XRT refined analysis
  53. GRB 090727: optical observations
  54. GRB 090726: GRT Optical Observation
  55. GRB 090727: Swift/UVOT Upper Limits
  56. GRB 090728: Swift/UVOT Upper Limits
  57. GRB 090728: Enhanced Swift-XRT position
  58. GRB 090727: I-band observations from 1.23m CAHA
  59. GRB 090728, RIMOTS optical upper limits
  60. GRB 090728A: Faulkes Telescope North Optical Afterglow Candidate
  61. GRB 090728: Swift detection of a burst
  62. GRB 090727: Swift-BAT refined analysis
  63. GRB 090727: Swift-XRT refined analysis
  64. GRB 090727: Liverpool Telescope Afterglow Confirmation and Optical Flare
  65. GRB 090727: Enhanced Swift-XRT position
  66. GRB 090715B: Late-time Lick 3m observations
  67. GRB 090727: Liverpool Telescope possible OT candidate
  68. GRB 090727: Swift detection of a burst
  69. GRB090726: Swift/UVOT observations
  70. GRB 090726, Swift-BAT refined analysis
  71. GRB 090726: Afterglow candidate photometryfrom Crni Vrh
  72. GRB 090726: D50 optical observations
  73. GRB 090711: Fermi GBM detection
  74. GRB090726: 6-meter telescope redshift
  75. GRB 090726: Swift-XRT Team refined analysis
  76. GRB 090726: Enhanced Swift-XRT position
  77. GRB 090726: optical transient candidate
  78. GRB 090726: Swift/UVOT Finding Chart Observation
  79. GRB 090726: Swift-XRT position of probable counterpart
  80. GRB 090726: Swift detection of a burst
  81. Swift Trigger 358354 is not a GRB
  82. Konus-Wind and Konus-RF observations of GRB 090719
  83. Konus-RF and Konus-Wind observations of GRB 090718B
  84. Fermi Gamma-ray Burst Monitor triggers 269935914 through 270021937 are not GRBs
  85. Konus-Wind observations of bright hard GRB 090720B
  86. IPN Triangulation of bright GRB 090720B
  87. GRB 090720: Gemini-North Imaging and Optical Afterglow
  88. GRB 090720B: Fermi GBM detection
  89. Swift XRT and UVOT refned analysis of GRB 090720
  90. GRB 090709A: Swift XRT Timing Analysis
  91. GRB 090715B: VLA radio detection
  92. GRB 090720 Source found in ground processing of Swift-BAT data
  93. GRB 090717B: Fermi GBM detection
  94. GRB 090717: Fermi GBM detection
  95. GRB 090719: Fermi GBM detection
  96. GRB 090718B: Fermi GBM detection
  97. GRB 090718: Fermi GBM detection
  98. GRB 090720: Fermi GBM detection
  99. GRB 090715B: further NOT optical observations
  100. GRB 090715A: Suzaku WAM observation of the prompt emission

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