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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 061201: Swift XRT Team refined analysis
  2. GRB 061201: VLT optical observations
  3. GRB 061201: Initial UVOT Observations
  4. GRB 061201, Swift-BAT refined analysis of the SHB
  5. GRB 061201: Swift detection of a short hard burst
  6. GRB 061201: Coincidence with a Galaxy Cluster
  7. GRB 061122: GETS observation
  8. GRB 061121, SMARTS optical/IR observations
  9. GRB 061121: flattening of the decay
  10. INT+WFC observations of GRB 061126
  11. GRB 061126: Possible Jet Break
  12. GRB 061121: Second Epoch ATCA Radio Observations
  13. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  14. Swift XRT on-board boresight update
  15. GRB 061121: ATCA & WSRT Radio Observations
  16. GRB061121: optical observations
  17. GRB 061126: Early Super-LOTIS Observations
  18. GRB 061126: optical observation
  19. RHESSI Spectrum of GRB061126
  20. GRB 061126: Tautenburg afterglow observations
  21. GRB061126: Optical afterglow observations from MIRO
  22. GRB061126: Optical afterglow observations from MIRO
  23. GRB 061126 : SDSS Pre-Burst Observations
  24. GRB 061126: Swift-XRT refined analysis
  25. GRB 061126: Swift/UVOT Observations
  26. GRB 061126, Swift-BAT refined analysis
  27. GRB 061126: SARA Observations
  28. GRB 061126: Early Detection of the IR Afterglow
  29. GRB 061126: Faulkes Telescope North Optical Observations
  30. GRB 061126: Swift/UVOT Afterglow Detection
  31. GRB 061126: XRT position
  32. GRB 061126: Swift detection of a burst
  33. GRB 061121: MDM Continued Monitoring
  34. GRB 061122: Confirmation of X-ray/Optical Afterglow
  35. GRB 061121: MDM Continuing Optical Decay
  36. GRB061121: optical observations
  37. GRB 061122: Candidate Optical Afterglow
  38. GRB 061121: Ep,i - Eiso correlation
  39. GRB 061121: MDM Optical Decay
  40. GRB061122: Swift/UVOT Optical Observations
  41. GRB 061121: ART detection in Ic
  42. GRB061121: P60 Observations
  43. Radio detection of GRB 061121
  44. GRB061122: Swift-XRT position
  45. Konus-Wind observation of GRB 061122
  46. GRB 061121: MDM Optical Observations
  47. GRB 061121 declared "Burst of Interest" by Swift team
  48. RHESSI Spectrum of GRB061121
  49. Konus-Wind and Konus-A observations of GRB 061121
  50. INTEGRAL results on GRB 061122
  51. Swift-BAT trigger 239987 is not a GRB
  52. GRB 061122A: a long GRB detected by INTEGRAL
  53. GRB 061121: Swift/UVOT Observations
  54. GRB 061121: Swift-XRT Team Refined Analysis
  55. GRB 061121, Swift-BAT refined analysis
  56. GRB061121, optical observation
  57. GRB 061121 : Planned XMM-Newton observation
  58. GRB 061121: Optical observation at the KANATA 1.5m telescope
  59. GRB 061121: Faulkes Telescope North Optical Observation
  60. GRB061121: Spectroscopic Redshift
  61. GRB061121: Keck spectroscopic observations
  62. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  63. GRB 061121: Swift detection of a bright burst with an optical counterpart
  64. GRB 060605: NIR Observations
  65. GRB 050915B: optical afterglow
  66. GRB 060111B: Swift UVOT Refined Magnitudes
  67. Swift-BAT triggers 238544 and 238546 are not GRBs
  68. GRB061110A: Correction to GCN5817
  69. GRB 061110A: refined R-band analysis
  70. GRB 061110B: NIR Observations
  71. Swift TOO observations of GRB061110A
  72. Swift/UVOT Upper Limits for GRB061110b
  73. Swift/UVOT Upper Limits for GRB061110a
  74. GRB 061110A - VLT tentative redshift
  75. GRB 061110B: Swift XRT refined analysis
  76. GRB 061110B, Swift-BAT refined analysis
  77. GRB 061110B: VLT redshift
  78. GRB061110B: Optical observations at Crni Vrh
  79. GRB 061110B: NOT optical observations
  80. GRB 061110A: Swift XRT refined analysis
  81. GRB 061110B: Swift/XRT position
  82. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  83. GRB 061110B: Swift-UVOT Initial Observation
  84. GRB 061110A, Swift-BAT refined analysis
  85. GRB 061110B: TAROT Calern observatory optical observations
  86. GRB 061110B: Swift detection of a burst
  87. GRB 061110: NOT observations
  88. GRB 061110: Candidate confirmed
  89. GRB 061110 : Optical afterglow candidate
  90. GRB 061110: ROTSE-III Optical Limits
  91. GRB 061110: Swift detection of a burst
  92. GRB061110A - Optical Non-detection
  93. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  94. GRB 061109: optical observation
  95. GRB 061109: TAROT Calern observatory optical observations
  96. GRB 061109: Swift detection of a possible burst
  97. GRB061028: MAGIC telescope GeV observation
  98. GRB 061027: TAROT La Silla observatory optical observations
  99. GRB 061007: Third Epoch ATCA Radio Observations
  100. GRB061019: second epoch CrAO observations

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