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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 090817: a long GRB localized by INTEGRAL
  2. VLA radio non-detection of GRB 090812
  3. GRB 090815B: Fermi GBM detection
  4. GRB 090815: Fermi GBM detection
  5. GRB 090813: CrAO optical obsevations
  6. GRB 090814B: Confirmation of the X-ray afterglow
  7. GRB090814A: NOT optical follow-ups
  8. GRB 090814B: I-band observations from 1.23m CAHA telescope
  9. GRB 090814B: Swift/UVOT Upper Limits
  10. GRB 090814B: Liverpool Telescope Observations
  11. Fermi Gamma-ray Burst Monitor trigger 271934815 is not a GRB
  12. GRB 090814C: Fermi GBM detection
  13. GRB 090814B: Swift-XRT detection of a possible afterglow.
  14. GRB 090814A: Swift/UVOT Observations
  15. GRB 090814A: Swift-XRT Team Refined Analysis
  16. GRB 090814A, RIMOTS optical upper limits
  17. GRB 090814A: Swift-BAT refined analysis
  18. GRB 090813: correction to GCN 9787
  19. GRB090814A: VLT spectroscopy
  20. GRB 090814: Enhanced Swift-XRT position
  21. GRB 090814B: a long GRB localized by INTEGRAL
  22. GRB 090814: GROND Detection of an Optical Afterglow Candidate
  23. GRB 090814: Swift detection of a burst
  24. GRB 090813: Fermi GBM observation
  25. Fermi Gamma-ray Burst Monitor trigger 271446248 is not a GRB
  26. GRB 090813: Swift-XRT refined analysis
  27. Fermi Gamma-ray Burst Monitor trigger 271833016 is not a GRB
  28. GRB 090813, Swift-BAT refined analysis
  29. Konus-Wind observations of GRB090813
  30. GRB090813: Swift/UVOT upper limits
  31. GRB 090813: Enhanced Swift-XRT position
  32. GRB 090813: Liverpool Telescope afterglow confirmation
  33. GRB 090813: P60 Optical Afterglow Confirmation
  34. GRB 090813: optical candidate from 1.23m CAHA telescope
  35. GRB 090813: Swift detection of a burst
  36. GRB 090812: WIRO NIR upper limit
  37. GRB 090812: Faulkes Telescope South Continued Optical Monitoring
  38. GRB 090812: RAPTOR detections during the burst
  39. GRB 090812: Swift XRT refined analysis
  40. GRB 090812, RIMOTS optical upper limits
  41. GRB 090812 Swift-BAT Refined Analysis
  42. GRB090812: Swift/UVOT observations
  43. GRB 090812: GROND Observations of the Optical/NIR Afterglow
  44. GRB 090812: Enhanced Swift-XRT position
  45. GRB 090812 VLT redshift
  46. GRB 090812: Liverpool Telescope afterglow confirmation
  47. GRB 090812: P60 Confirmation of Optical Afterglow
  48. GRB 090812: Swift detection of a burst with an optical counterpart
  49. GRB 090807B: Fermi GBM detection
  50. GRB 090809: Further NOT optical observations
  51. VLA radio upper limit on GRB 090809
  52. GRB 090621B: MAGIC telescope GeV observation
  53. GRB 090621A: MAGIC telescope GeV observation
  54. GRB 090809: WHT observations
  55. GRB 090809 X-shooter redshift
  56. GRB 090809B: Fermi GBM detection
  57. GRB 090809: Swift-XRT refined analysis
  58. GRB090809: Swift/UVOT observations
  59. GRB 090809: Enhanced Swift-XRT position
  60. GRB 090809: Swift-BAT refined analysis
  61. GRB 090809: afterglow confirmation at the NOT
  62. GRB 090809: Swift detection of a burst with a possible optical counterpart
  63. GRB 090807: Liverpool Telescope observations
  64. GRB 090807: MITSuME optical upper limit
  65. GRB 090807: Swift/UVOT Upper Limits
  66. GRB 090807: Swift-XRT refined analysis
  67. GRB 090807, Swift-BAT refined analysis
  68. GRB 090807: Enhanced Swift-XRT position
  69. GRB 090807, RIMOTS optical upper limits
  70. GRB 090807: Swift detection of a burst
  71. Fermi Gamma-ray Burst Monitor trigger 271275771 is not a GRB
  72. GRB 090802B: Fermi GBM detection
  73. IPN Triangulation and Konus-Wind observaions of GRB090727B
  74. GRB 090802: Fermi GBM detection
  75. GRB 090726: optical observation
  76. Swift-BAT trigger 358760 is most likely not a GRB
  77. Swift trigger 358760 is probably a noise event
  78. GRB 090717A: Suzaku WAM observation of the prompt emission
  79. GRB 090709A : Quick look analysis of the Suzaku observation
  80. GRB 090728: Swift-BAT refined analysis
  81. GRB 090727: GRT Optical Observation
  82. GRB 090728: Swift XRT refined analysis
  83. GRB 090727: optical observations
  84. GRB 090726: GRT Optical Observation
  85. GRB 090727: Swift/UVOT Upper Limits
  86. GRB 090728: Swift/UVOT Upper Limits
  87. GRB 090728: Enhanced Swift-XRT position
  88. GRB 090727: I-band observations from 1.23m CAHA
  89. GRB 090728, RIMOTS optical upper limits
  90. GRB 090728A: Faulkes Telescope North Optical Afterglow Candidate
  91. GRB 090728: Swift detection of a burst
  92. GRB 090727: Swift-BAT refined analysis
  93. GRB 090727: Swift-XRT refined analysis
  94. GRB 090727: Liverpool Telescope Afterglow Confirmation and Optical Flare
  95. GRB 090727: Enhanced Swift-XRT position
  96. GRB 090715B: Late-time Lick 3m observations
  97. GRB 090727: Liverpool Telescope possible OT candidate
  98. GRB 090727: Swift detection of a burst
  99. GRB090726: Swift/UVOT observations
  100. GRB 090726, Swift-BAT refined analysis

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