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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"

42572 results found.

  1. GRB 091104: Swift detection of a burst
  2. GRB 091102: LABOCA/APEX submm observations
  3. Fermi LAT Upper Limits on GRB 091010
  4. GRB 091102 : Faulkes Telescope South Upper Limits
  5. GRB 091102A: Fermi GBM observation
  6. GRB 091102: Swift-XRT refined analysis
  7. GRB 091102: Swift/UVOT Upper Limits
  8. GRB 091102: GROND Upper Limits
  9. GRB 091102: BOOTES-3 observations
  10. GRB 091102: Swift-BAT refined analysis
  11. GRB 091102: Swift/XRT localization
  12. GRB 091102: ROTSE-III Optical Limits
  13. GRB 091102: Swift/UVOT Finding Chart Observation
  14. GRB 091102: Swift detection of a burst
  15. GRB 091024: optical observations
  16. GRB 091031: Fermi GBM detection
  17. GRB 091024: Fermi LAT upper limits
  18. GRB 090926a, SMARTS optical/IR afterglow observations
  19. GRB 091018: Skynet/PROMPT Observations of Possible Host Galaxy
  20. GRB 091029, SMARTS optical/IR afterglow observations
  21. GRB 091018, SMARTS optical/IR afterglow observations
  22. GRB 090920: Skynet/DSO Detection
  23. GRB091029: Swift/UVOT observations
  24. GRB 091029: Skynet/PROMPT Continued Observations of Fading
  25. GRB 091029: Swift XRT refined analysis
  26. Fermi Gamma-ray Burst Monitor trigger 091028818 is not a GRB
  27. GRB 091029: BOOTES-3 observations
  28. GRB 091029: Swift-BAT refined analysis
  29. GRB 091029: Enhanced Swift-XRT position
  30. GRB091024 optical observations
  31. GRB 091029: Gemini-South Redshift
  32. GRB 091029: Skynet/PROMPT Observations of Peak and Fading
  33. GRB 091029: GROND Detection of the Optical/NIR Afterglow
  34. GRB 091029: Swift detection of a burst with an optical counterpart
  35. A mistake in testing a new function in Swift
  36. GRB 091020: Fermi GBM observation
  37. GRB 091026: Suzaku WAM observation of the prompt emission
  38. GRB 091024: Keck/LRIS Spectroscopy
  39. GRB 091026: GROND Upper Limits
  40. GRB 091020: Late TLS detection
  41. GRB 091026: Swift-BAT refined analysis
  42. Radio afterglow detection from GRB 091020
  43. GRB 091026: Swift-XRT refined analysis
  44. GRB 091026: Enhanced Swift-XRT position
  45. Konus-Wind and Konus-RF observations of GRB 091024
  46. GRB 091026: Swift detection of a Gamma Ray Burst
  47. GRB 091020 : Xinglong TNT upper limit
  48. GRB091024 Swift/UVOT Upper Limits
  49. GRB 091024: TLS Upper Limit
  50. GRB 091020: Early TLS Multicolor detections, red afterglow
  51. GRB 091024: KAIT optical afterglow observations
  52. GRB 091024: Super-LOTIS early observations
  53. GRB091024: VRcIc Afterglow Observations
  54. GRB 091024: Swift-BAT refined analysis
  55. GRB 091024: Fermi GBM Observations
  56. GRB 091024: Swift-XRT team refined analysis
  57. Swift-BAT trigger 373691 is a galactic bulge transient
  58. GRB 091024 : Faulkes Telescope North - Afterglow Confirmation
  59. GRB 091024 Gemini-North redshift
  60. GRB 091024: GRAS004 optical observations
  61. GRB 091024: Faulkes Telescope North Afterglow Candidate
  62. GRB 091024: Swift detection of a burst
  63. GRB 091018: Skynet/PROMPT Continued Observations of Fading
  64. GRB 091020: Additional Lick observations
  65. Konus-Wind observations of GRB 091020 (correction to GCN 10057)
  66. GRB 091020: Lick observations
  67. Konus-Wind observations of GRB 091010
  68. GRB 091020: Swift-XRT refined analysis
  69. GRB 091018: Swift XRT refined analysis
  70. GRB091020 Swift/UVOT observations
  71. GRB 091020: NOT spectroscopic redshift
  72. GRB 091020: MASTER optical transient polarimetry
  73. GRB 091020, Swift-BAT refined analysis
  74. GRB 091020: Enhanced Swift-XRT position
  75. GRB 090926A: Late-time Gemini South Observations and Possible Jet Break
  76. GRB 091020: Swift detection of a burst with an optical afterglow
  77. GRB 091018: Skynet/PROMPT Observations of Fading
  78. Konus-RF observation of GRB 091018
  79. GRB 091018 : Faulkes Telescope South Observations
  80. GRB 091018: BOOTES-3 observations
  81. GRB 091018: VLT/X-shooter spectra
  82. GRB091018: Swift/UVOT observations
  83. GRB 091018: Swift-BAT refined analysis
  84. GRB 091018: GROND observations
  85. GRB091018: Magellan Echellette Observations
  86. GRB 091018: Enhanced Swift-XRT position
  87. GRB 091018: ROTSE-III Detection of Optical Counterpart
  88. GRB 091015: Skynet/PROMPT Observations
  89. GRB 091018: Swift detection of a burst with optical afterglow
  90. Fwd: GRB 091003: Possible Supernova Component Retraction
  91. GRB 091003: Possible Supernova Component
  92. GRB 091003: Gemini-N redshift of possible host galaxy
  93. GRB 091010: optical obsevation
  94. GRB 091015: RTT150 optical observations
  95. GRB 090726 R band observations
  96. GRB 091010: optical afterglow candidate rejection
  97. GRB 091015: correction to GCN 10025
  98. GRB 090815: a faint long GRB localized by INTEGRAL
  99. GRB 091010: Swift-XRT refined analysis
  100. GRB 091010: Suzaku WAM observation of the prompt emission

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