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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 061210: Swift-BAT detection of a short burst
  2. Optical Afterglow observations of GRB 061126
  3. GRB061126: optical observations
  4. GRB 060926: MASTER: discovery of the optical flare
  5. GRB061126: update on the Swift-XRT afterglow light curve
  6. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  7. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  8. GRB 061202: TORTOREM optical upper limits
  9. GRB 061201: VLT optical decay
  10. GRB 061201: SOAR Confirmation of Candidate Afterglow
  11. GRB061126 : NMSU 1.0m observations
  12. GRB 061202: Swift XRT refined analysis
  13. GRB061202: FRAM early follow-up limit
  14. GRB061202 optical limit by "Pi of the Sky"
  15. Konus-Wind observation of GRB 061201
  16. GRB061202: optical/NIR observations with REM
  17. GRB061202: Swift/UVOT Upper Limits
  18. GRB 061202, Swift-BAT refined analysis
  19. GRB 061202: Swift detection of a burst
  20. GRB 061201: Swift XRT Team refined analysis
  21. GRB 061201: VLT optical observations
  22. GRB 061201: Initial UVOT Observations
  23. GRB 061201, Swift-BAT refined analysis of the SHB
  24. GRB 061201: Swift detection of a short hard burst
  25. GRB 061201: Coincidence with a Galaxy Cluster
  26. GRB 061122: GETS observation
  27. GRB 061121, SMARTS optical/IR observations
  28. GRB 061121: flattening of the decay
  29. INT+WFC observations of GRB 061126
  30. GRB 061126: Possible Jet Break
  31. GRB 061121: Second Epoch ATCA Radio Observations
  32. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  33. Swift XRT on-board boresight update
  34. GRB 061121: ATCA & WSRT Radio Observations
  35. GRB061121: optical observations
  36. GRB 061126: Early Super-LOTIS Observations
  37. GRB 061126: optical observation
  38. RHESSI Spectrum of GRB061126
  39. GRB 061126: Tautenburg afterglow observations
  40. GRB061126: Optical afterglow observations from MIRO
  41. GRB061126: Optical afterglow observations from MIRO
  42. GRB 061126 : SDSS Pre-Burst Observations
  43. GRB 061126: Swift-XRT refined analysis
  44. GRB 061126: Swift/UVOT Observations
  45. GRB 061126, Swift-BAT refined analysis
  46. GRB 061126: SARA Observations
  47. GRB 061126: Early Detection of the IR Afterglow
  48. GRB 061126: Faulkes Telescope North Optical Observations
  49. GRB 061126: Swift/UVOT Afterglow Detection
  50. GRB 061126: XRT position
  51. GRB 061126: Swift detection of a burst
  52. GRB 061121: MDM Continued Monitoring
  53. GRB 061122: Confirmation of X-ray/Optical Afterglow
  54. GRB 061121: MDM Continuing Optical Decay
  55. GRB061121: optical observations
  56. GRB 061122: Candidate Optical Afterglow
  57. GRB 061121: Ep,i - Eiso correlation
  58. GRB 061121: MDM Optical Decay
  59. GRB061122: Swift/UVOT Optical Observations
  60. GRB 061121: ART detection in Ic
  61. GRB061121: P60 Observations
  62. Radio detection of GRB 061121
  63. GRB061122: Swift-XRT position
  64. Konus-Wind observation of GRB 061122
  65. GRB 061121: MDM Optical Observations
  66. GRB 061121 declared "Burst of Interest" by Swift team
  67. RHESSI Spectrum of GRB061121
  68. Konus-Wind and Konus-A observations of GRB 061121
  69. INTEGRAL results on GRB 061122
  70. Swift-BAT trigger 239987 is not a GRB
  71. GRB 061122A: a long GRB detected by INTEGRAL
  72. GRB 061121: Swift/UVOT Observations
  73. GRB 061121: Swift-XRT Team Refined Analysis
  74. GRB 061121, Swift-BAT refined analysis
  75. GRB061121, optical observation
  76. GRB 061121 : Planned XMM-Newton observation
  77. GRB 061121: Optical observation at the KANATA 1.5m telescope
  78. GRB 061121: Faulkes Telescope North Optical Observation
  79. GRB061121: Spectroscopic Redshift
  80. GRB061121: Keck spectroscopic observations
  81. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  82. GRB 061121: Swift detection of a bright burst with an optical counterpart
  83. GRB 060605: NIR Observations
  84. GRB 050915B: optical afterglow
  85. GRB 060111B: Swift UVOT Refined Magnitudes
  86. Swift-BAT triggers 238544 and 238546 are not GRBs
  87. GRB061110A: Correction to GCN5817
  88. GRB 061110A: refined R-band analysis
  89. GRB 061110B: NIR Observations
  90. Swift TOO observations of GRB061110A
  91. Swift/UVOT Upper Limits for GRB061110b
  92. Swift/UVOT Upper Limits for GRB061110a
  93. GRB 061110A - VLT tentative redshift
  94. GRB 061110B: Swift XRT refined analysis
  95. GRB 061110B, Swift-BAT refined analysis
  96. GRB 061110B: VLT redshift
  97. GRB061110B: Optical observations at Crni Vrh
  98. GRB 061110B: NOT optical observations
  99. GRB 061110A: Swift XRT refined analysis
  100. GRB 061110B: Swift/XRT position

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