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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 061121, SMARTS optical/IR observations
  2. GRB 061121: flattening of the decay
  3. INT+WFC observations of GRB 061126
  4. GRB 061126: Possible Jet Break
  5. GRB 061121: Second Epoch ATCA Radio Observations
  6. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  7. Swift XRT on-board boresight update
  8. GRB 061121: ATCA & WSRT Radio Observations
  9. GRB061121: optical observations
  10. GRB 061126: Early Super-LOTIS Observations
  11. GRB 061126: optical observation
  12. RHESSI Spectrum of GRB061126
  13. GRB 061126: Tautenburg afterglow observations
  14. GRB061126: Optical afterglow observations from MIRO
  15. GRB061126: Optical afterglow observations from MIRO
  16. GRB 061126 : SDSS Pre-Burst Observations
  17. GRB 061126: Swift-XRT refined analysis
  18. GRB 061126: Swift/UVOT Observations
  19. GRB 061126, Swift-BAT refined analysis
  20. GRB 061126: SARA Observations
  21. GRB 061126: Early Detection of the IR Afterglow
  22. GRB 061126: Faulkes Telescope North Optical Observations
  23. GRB 061126: Swift/UVOT Afterglow Detection
  24. GRB 061126: XRT position
  25. GRB 061126: Swift detection of a burst
  26. GRB 061121: MDM Continued Monitoring
  27. GRB 061122: Confirmation of X-ray/Optical Afterglow
  28. GRB 061121: MDM Continuing Optical Decay
  29. GRB061121: optical observations
  30. GRB 061122: Candidate Optical Afterglow
  31. GRB 061121: Ep,i - Eiso correlation
  32. GRB 061121: MDM Optical Decay
  33. GRB061122: Swift/UVOT Optical Observations
  34. GRB 061121: ART detection in Ic
  35. GRB061121: P60 Observations
  36. Radio detection of GRB 061121
  37. GRB061122: Swift-XRT position
  38. Konus-Wind observation of GRB 061122
  39. GRB 061121: MDM Optical Observations
  40. GRB 061121 declared "Burst of Interest" by Swift team
  41. RHESSI Spectrum of GRB061121
  42. Konus-Wind and Konus-A observations of GRB 061121
  43. INTEGRAL results on GRB 061122
  44. Swift-BAT trigger 239987 is not a GRB
  45. GRB 061122A: a long GRB detected by INTEGRAL
  46. GRB 061121: Swift/UVOT Observations
  47. GRB 061121: Swift-XRT Team Refined Analysis
  48. GRB 061121, Swift-BAT refined analysis
  49. GRB061121, optical observation
  50. GRB 061121 : Planned XMM-Newton observation
  51. GRB 061121: Optical observation at the KANATA 1.5m telescope
  52. GRB 061121: Faulkes Telescope North Optical Observation
  53. GRB061121: Spectroscopic Redshift
  54. GRB061121: Keck spectroscopic observations
  55. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  56. GRB 061121: Swift detection of a bright burst with an optical counterpart
  57. GRB 060605: NIR Observations
  58. GRB 050915B: optical afterglow
  59. GRB 060111B: Swift UVOT Refined Magnitudes
  60. Swift-BAT triggers 238544 and 238546 are not GRBs
  61. GRB061110A: Correction to GCN5817
  62. GRB 061110A: refined R-band analysis
  63. GRB 061110B: NIR Observations
  64. Swift TOO observations of GRB061110A
  65. Swift/UVOT Upper Limits for GRB061110b
  66. Swift/UVOT Upper Limits for GRB061110a
  67. GRB 061110A - VLT tentative redshift
  68. GRB 061110B: Swift XRT refined analysis
  69. GRB 061110B, Swift-BAT refined analysis
  70. GRB 061110B: VLT redshift
  71. GRB061110B: Optical observations at Crni Vrh
  72. GRB 061110B: NOT optical observations
  73. GRB 061110A: Swift XRT refined analysis
  74. GRB 061110B: Swift/XRT position
  75. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  76. GRB 061110B: Swift-UVOT Initial Observation
  77. GRB 061110A, Swift-BAT refined analysis
  78. GRB 061110B: TAROT Calern observatory optical observations
  79. GRB 061110B: Swift detection of a burst
  80. GRB 061110: NOT observations
  81. GRB 061110: Candidate confirmed
  82. GRB 061110 : Optical afterglow candidate
  83. GRB 061110: ROTSE-III Optical Limits
  84. GRB 061110: Swift detection of a burst
  85. GRB061110A - Optical Non-detection
  86. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  87. GRB 061109: optical observation
  88. GRB 061109: TAROT Calern observatory optical observations
  89. GRB 061109: Swift detection of a possible burst
  90. GRB061028: MAGIC telescope GeV observation
  91. GRB 061027: TAROT La Silla observatory optical observations
  92. GRB 061007: Third Epoch ATCA Radio Observations
  93. GRB061019: second epoch CrAO observations
  94. GRB 061028: Swift/XRT Astrometry Correction
  95. GRB 061102: Swift/UVOT Magnitude Upper Limits
  96. GRB 061102, XRT refined analysis
  97. GRB 061004: Further VLT/NTT observations
  98. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  99. GRB061102B: Super-LOTIS observations
  100. GRB 061028: Optical R passband observations

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