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

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