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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 091029: Enhanced Swift-XRT position
  2. GRB091024 optical observations
  3. GRB 091029: Gemini-South Redshift
  4. GRB 091029: Skynet/PROMPT Observations of Peak and Fading
  5. GRB 091029: GROND Detection of the Optical/NIR Afterglow
  6. GRB 091029: Swift detection of a burst with an optical counterpart
  7. A mistake in testing a new function in Swift
  8. GRB 091020: Fermi GBM observation
  9. GRB 091026: Suzaku WAM observation of the prompt emission
  10. GRB 091024: Keck/LRIS Spectroscopy
  11. GRB 091024: YNAO-GMG observations
  12. GRB 091026: GROND Upper Limits
  13. GRB 091020: Late TLS detection
  14. GRB 091026: Swift-BAT refined analysis
  15. Radio afterglow detection from GRB 091020
  16. GRB 091026: Swift/UVOT Upper Limits
  17. GRB 091024: Burst was outside the Swift-BAT FOV after T0(BAT)+460sec
  18. GRB 091026: Swift-XRT refined analysis
  19. GRB 091026: Enhanced Swift-XRT position
  20. Konus-Wind and Konus-RF observations of GRB 091024
  21. GRB 091026: Updated Swift-XRT position
  22. GRB 091026: Swift detection of a Gamma Ray Burst
  23. GRB 091020 : Xinglong TNT upper limit
  24. Swift-BAT Triggers 373776-373778 are not real
  25. GRB091024 Swift/UVOT Upper Limits
  26. GRB 091024: TLS Upper Limit
  27. GRB 091020: Early TLS Multicolor detections, red afterglow
  28. GRB 091024: KAIT optical afterglow observations
  29. GRB 091024: Super-LOTIS early observations
  30. GRB091024: VRcIc Afterglow Observations
  31. GRB 091024: Swift-BAT refined analysis
  32. Swift-BAT Triggers 373679-373684 are not real
  33. GRB 091024: Fermi GBM Observations
  34. GRB 091024: Swift-XRT team refined analysis
  35. Swift-BAT trigger 373691 is a galactic bulge transient
  36. GRB 091024: Xinglong TNT optical observation
  37. GRB 091024 : Faulkes Telescope North - Afterglow Confirmation
  38. GRB 091024 Gemini-North redshift
  39. GRB 091024: GRAS004 optical observations
  40. GRB 091024: Faulkes Telescope North Afterglow Candidate
  41. GRB 091024: Swift detection of a burst
  42. GRB 091018: Skynet/PROMPT Continued Observations of Fading
  43. GRB 091020: Additional Lick observations
  44. Konus-Wind observations of GRB 091020 (correction to GCN 10057)
  45. GRB 091020: Lick observations
  46. Konus-Wind observations of GRB 091010
  47. GRB 091020: Swift-XRT refined analysis
  48. GRB 091018: Swift XRT refined analysis
  49. GRB091020 Swift/UVOT observations
  50. GRB 091020: NOT spectroscopic redshift
  51. GRB 091020: MASTER optical transient polarimetry
  52. GRB 091020, Swift-BAT refined analysis
  53. GRB 091020: Enhanced Swift-XRT position
  54. GRB 090926A: Late-time Gemini South Observations and Possible Jet Break
  55. GRB 091020: Swift detection of a burst with an optical afterglow
  56. GRB 091018: miniTAO/ANIR Observations
  57. GRB 091018: Skynet/PROMPT Observations of Fading
  58. Konus-RF observation of GRB 091018
  59. GRB 091018 : Faulkes Telescope South Observations
  60. GRB 091018: BOOTES-3 observations
  61. GRB 091018: VLT/X-shooter spectra
  62. GRB091018: Swift/UVOT observations
  63. GRB 091018: Swift-BAT refined analysis
  64. GRB 091018: GROND observations
  65. GRB091018: Magellan Echellette Observations
  66. GRB 091018: Enhanced Swift-XRT position
  67. GRB 091018: ROTSE-III Detection of Optical Counterpart
  68. GRB 091015: Skynet/PROMPT Observations
  69. GRB 091018: Swift detection of a burst with optical afterglow
  70. Fwd: GRB 091003: Possible Supernova Component Retraction
  71. GRB 091003: Possible Supernova Component
  72. GRB 091003: Gemini-N redshift of possible host galaxy
  73. GRB 091010: optical obsevation
  74. GRB 091015: RTT150 optical observations
  75. GRB 090726 R band observations
  76. GRB 091010: optical afterglow candidate rejection
  77. GRB 091015: correction to GCN 10025
  78. GRB 090815: a faint long GRB localized by INTEGRAL
  79. GRB 091010: Swift-XRT refined analysis
  80. GRB 091010: Suzaku WAM observation of the prompt emission
  81. GRB 091010: AGILE-MCAL measurement and GRID upper limit
  82. Radio observation of GRB090927 with ATCA
  83. Radio observation of GRB090926a with ATCA
  84. Radio observation of GRB080916c with ATCA
  85. GRB 091010: Fermi GBM observation
  86. GRB 091010: Faulkes Telescope North observations
  87. GRB 090531A: Skynet/PROMPT Observations
  88. GRB 090530A: Skynet/DSO Detections
  89. GRB 091010: RXTE detection
  90. Konus-Wind observations of GRB 091010
  91. GRB 091010: Enhanced XRT position
  92. GRB 091010 optical upper limits
  93. Detection of a short GRB 090929A by RT-2 Experiment
  94. RT-2 observation of the bright GRB 090926A
  95. GRB 091010: GROND afterglow candidate
  96. GRB 091010: Swift/UVOT Upper Limits
  97. GRB 091010: Swift-XRT position
  98. SuperAGILE GRB is 091010 and not 090910
  99. GRB 090910: SuperAGILE Localization of a Long GRB
  100. GRB 090926A: Skynet/PROMPT Observations of Day 6 - 11 Fading

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