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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 061126: Radio Observations
  2. GRB061210: Radio Observations
  3. GRB061201, VLT optical decay: correction
  4. GRB 061126: a GRB detected off-axis by INTEGRAL
  5. GRB 061202: Suzaku WAM observation of the prompt emission
  6. GRB 061210: MDM Observation
  7. GRB 061210, Swift-BAT refined analysis of the SHB
  8. GRB 061210: Swift-BAT detection of a short burst
  9. Optical Afterglow observations of GRB 061126
  10. GRB061126: optical observations
  11. GRB 060926: MASTER: discovery of the optical flare
  12. GRB061126: update on the Swift-XRT afterglow light curve
  13. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  14. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  15. GRB 061202: TORTOREM optical upper limits
  16. GRB 061201: VLT optical decay
  17. GRB 061201: SOAR Confirmation of Candidate Afterglow
  18. GRB061126 : NMSU 1.0m observations
  19. GRB 061202: Swift XRT refined analysis
  20. GRB061202: FRAM early follow-up limit
  21. GRB061202 optical limit by "Pi of the Sky"
  22. Konus-Wind observation of GRB 061201
  23. GRB061202: optical/NIR observations with REM
  24. GRB061202: Swift/UVOT Upper Limits
  25. GRB 061202, Swift-BAT refined analysis
  26. GRB 061202: Swift detection of a burst
  27. GRB 061201: Swift XRT Team refined analysis
  28. GRB 061201: VLT optical observations
  29. GRB 061201: Initial UVOT Observations
  30. GRB 061201, Swift-BAT refined analysis of the SHB
  31. GRB 061201: Swift detection of a short hard burst
  32. GRB 061201: Coincidence with a Galaxy Cluster
  33. GRB 061122: GETS observation
  34. GRB 061121, SMARTS optical/IR observations
  35. GRB 061121: flattening of the decay
  36. INT+WFC observations of GRB 061126
  37. GRB 061126: Possible Jet Break
  38. GRB 061121: Second Epoch ATCA Radio Observations
  39. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  40. Swift XRT on-board boresight update
  41. GRB 061121: ATCA & WSRT Radio Observations
  42. GRB061121: optical observations
  43. GRB 061126: Early Super-LOTIS Observations
  44. GRB 061126: optical observation
  45. RHESSI Spectrum of GRB061126
  46. GRB 061126: Tautenburg afterglow observations
  47. GRB061126: Optical afterglow observations from MIRO
  48. GRB061126: Optical afterglow observations from MIRO
  49. GRB 061126 : SDSS Pre-Burst Observations
  50. GRB 061126: Swift-XRT refined analysis
  51. GRB 061126: Swift/UVOT Observations
  52. GRB 061126, Swift-BAT refined analysis
  53. GRB 061126: SARA Observations
  54. GRB 061126: Early Detection of the IR Afterglow
  55. GRB 061126: Faulkes Telescope North Optical Observations
  56. GRB 061126: Swift/UVOT Afterglow Detection
  57. GRB 061126: XRT position
  58. GRB 061126: Swift detection of a burst
  59. GRB 061121: MDM Continued Monitoring
  60. GRB 061122: Confirmation of X-ray/Optical Afterglow
  61. GRB 061121: MDM Continuing Optical Decay
  62. GRB061121: optical observations
  63. GRB 061122: Candidate Optical Afterglow
  64. GRB 061121: Ep,i - Eiso correlation
  65. GRB 061121: MDM Optical Decay
  66. GRB061122: Swift/UVOT Optical Observations
  67. GRB 061121: ART detection in Ic
  68. GRB061121: P60 Observations
  69. Radio detection of GRB 061121
  70. GRB061122: Swift-XRT position
  71. Konus-Wind observation of GRB 061122
  72. GRB 061121: MDM Optical Observations
  73. GRB 061121 declared "Burst of Interest" by Swift team
  74. RHESSI Spectrum of GRB061121
  75. Konus-Wind and Konus-A observations of GRB 061121
  76. INTEGRAL results on GRB 061122
  77. Swift-BAT trigger 239987 is not a GRB
  78. GRB 061122A: a long GRB detected by INTEGRAL
  79. GRB 061121: Swift/UVOT Observations
  80. GRB 061121: Swift-XRT Team Refined Analysis
  81. GRB 061121, Swift-BAT refined analysis
  82. GRB061121, optical observation
  83. GRB 061121 : Planned XMM-Newton observation
  84. GRB 061121: Optical observation at the KANATA 1.5m telescope
  85. GRB 061121: Faulkes Telescope North Optical Observation
  86. GRB061121: Spectroscopic Redshift
  87. GRB061121: Keck spectroscopic observations
  88. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  89. GRB 061121: Swift detection of a bright burst with an optical counterpart
  90. GRB 060605: NIR Observations
  91. GRB 050915B: optical afterglow
  92. GRB 060111B: Swift UVOT Refined Magnitudes
  93. Swift-BAT triggers 238544 and 238546 are not GRBs
  94. GRB061110A: Correction to GCN5817
  95. GRB 061110A: refined R-band analysis
  96. GRB 061110B: NIR Observations
  97. Swift TOO observations of GRB061110A
  98. Swift/UVOT Upper Limits for GRB061110b
  99. Swift/UVOT Upper Limits for GRB061110a
  100. GRB 061110A - VLT tentative redshift

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