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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. GRB061202: FRAM early follow-up limit
  2. GRB061202 optical limit by "Pi of the Sky"
  3. Konus-Wind observation of GRB 061201
  4. GRB061202: optical/NIR observations with REM
  5. GRB061202: Swift/UVOT Upper Limits
  6. GRB 061202, Swift-BAT refined analysis
  7. GRB 061202: Swift detection of a burst
  8. GRB 061201: Swift XRT Team refined analysis
  9. GRB 061201: VLT optical observations
  10. GRB 061201: Initial UVOT Observations
  11. GRB 061201, Swift-BAT refined analysis of the SHB
  12. GRB 061201: Swift detection of a short hard burst
  13. GRB 061201: Coincidence with a Galaxy Cluster
  14. GRB 061122: GETS observation
  15. GRB 061121, SMARTS optical/IR observations
  16. GRB 061121: flattening of the decay
  17. INT+WFC observations of GRB 061126
  18. GRB 061126: Possible Jet Break
  19. GRB 061121: Second Epoch ATCA Radio Observations
  20. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  21. Swift XRT on-board boresight update
  22. GRB 061121: ATCA & WSRT Radio Observations
  23. GRB061121: optical observations
  24. GRB 061126: Early Super-LOTIS Observations
  25. GRB 061126: optical observation
  26. RHESSI Spectrum of GRB061126
  27. GRB 061126: Tautenburg afterglow observations
  28. GRB061126: Optical afterglow observations from MIRO
  29. GRB061126: Optical afterglow observations from MIRO
  30. GRB 061126 : SDSS Pre-Burst Observations
  31. GRB 061126: Swift-XRT refined analysis
  32. GRB 061126: Swift/UVOT Observations
  33. GRB 061126, Swift-BAT refined analysis
  34. GRB 061126: SARA Observations
  35. GRB 061126: Early Detection of the IR Afterglow
  36. GRB 061126: Faulkes Telescope North Optical Observations
  37. GRB 061126: Swift/UVOT Afterglow Detection
  38. GRB 061126: XRT position
  39. GRB 061126: Swift detection of a burst
  40. GRB 061121: MDM Continued Monitoring
  41. GRB 061122: Confirmation of X-ray/Optical Afterglow
  42. GRB 061121: MDM Continuing Optical Decay
  43. GRB061121: optical observations
  44. GRB 061122: Candidate Optical Afterglow
  45. GRB 061121: Ep,i - Eiso correlation
  46. GRB 061121: MDM Optical Decay
  47. GRB061122: Swift/UVOT Optical Observations
  48. GRB 061121: ART detection in Ic
  49. GRB061121: P60 Observations
  50. Radio detection of GRB 061121
  51. GRB061122: Swift-XRT position
  52. Konus-Wind observation of GRB 061122
  53. GRB 061121: MDM Optical Observations
  54. GRB 061121 declared "Burst of Interest" by Swift team
  55. RHESSI Spectrum of GRB061121
  56. Konus-Wind and Konus-A observations of GRB 061121
  57. INTEGRAL results on GRB 061122
  58. Swift-BAT trigger 239987 is not a GRB
  59. GRB 061122A: a long GRB detected by INTEGRAL
  60. GRB 061121: Swift/UVOT Observations
  61. GRB 061121: Swift-XRT Team Refined Analysis
  62. GRB 061121, Swift-BAT refined analysis
  63. GRB061121, optical observation
  64. GRB 061121 : Planned XMM-Newton observation
  65. GRB 061121: Optical observation at the KANATA 1.5m telescope
  66. GRB 061121: Faulkes Telescope North Optical Observation
  67. GRB061121: Spectroscopic Redshift
  68. GRB061121: Keck spectroscopic observations
  69. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  70. GRB 061121: Swift detection of a bright burst with an optical counterpart
  71. GRB 060605: NIR Observations
  72. GRB 050915B: optical afterglow
  73. GRB 060111B: Swift UVOT Refined Magnitudes
  74. Swift-BAT triggers 238544 and 238546 are not GRBs
  75. GRB061110A: Correction to GCN5817
  76. GRB 061110A: refined R-band analysis
  77. GRB 061110B: NIR Observations
  78. Swift TOO observations of GRB061110A
  79. Swift/UVOT Upper Limits for GRB061110b
  80. Swift/UVOT Upper Limits for GRB061110a
  81. GRB 061110A - VLT tentative redshift
  82. GRB 061110B: Swift XRT refined analysis
  83. GRB 061110B, Swift-BAT refined analysis
  84. GRB 061110B: VLT redshift
  85. GRB061110B: Optical observations at Crni Vrh
  86. GRB 061110B: NOT optical observations
  87. GRB 061110A: Swift XRT refined analysis
  88. GRB 061110B: Swift/XRT position
  89. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  90. GRB 061110B: Swift-UVOT Initial Observation
  91. GRB 061110A, Swift-BAT refined analysis
  92. GRB 061110B: TAROT Calern observatory optical observations
  93. GRB 061110B: Swift detection of a burst
  94. GRB 061110: NOT observations
  95. GRB 061110: Candidate confirmed
  96. GRB 061110 : Optical afterglow candidate
  97. GRB 061110: ROTSE-III Optical Limits
  98. GRB 061110: Swift detection of a burst
  99. GRB061110A - Optical Non-detection
  100. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event

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