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

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