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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 060605: Swift detection of a burst with optical counterpart
  2. GRB 060605: ROTSE-III Detection of Optical Counterpart
  3. GRB060604: Swift/UVOT detections
  4. GRB 060604: redshift
  5. GRB 060512: Keck Redshift
  6. GRB 060604 optical photometry
  7. GRB 060604: Swift-XRT Team refined analysis
  8. GRB 060604: BAT refined analysis
  9. GRB 060604A: ROTSE-III Optical Limits
  10. GRB 060604: Swift detection of a burst with possible optical counterpart
  11. GRB 060602A: Swift-BAT Refined Analysis: Correction
  12. GRB 060602B: XMM-Newton Survey Source
  13. GRB 060602B: Swift-XRT Refined Analysis
  14. GRB 060602B: Swift-BAT Refined Analysis
  15. GRB 060602B: Swift/UVOT observations
  16. GRB 060602A: Swift-BAT Refined Analysis
  17. GRB 060602B: RTT150 optical observations
  18. GRB 060211A : WIDGET simultaneous optical observations
  19. GRB060602A: optical observations(/transient?)
  20. GRB 060526: Tautenburg Second Epoch Observations
  21. GRB060602A: Bootes-IR observations
  22. GRB 060602B: Swift detection of a burst
  23. GRB060602B: Watcher observations - no OT candidate
  24. GRB060602B: BOOTES-IR candidate afterglow
  25. GRB060602 - SDSS Pre-Burst Observations
  26. GRB 060602: Swift detection of a burst
  27. GRB 060502A: Optical afterglow observations
  28. GRB 060526: Break in X-ray light curve
  29. GRB 060526: RTT150 optical observations
  30. GRB060526, optical observations
  31. GRB 051227 : WIDGET simultaneous optical observations
  32. GRB 051028 : WIDGET pre-trigger limit
  33. GRB 060526: RTT150 optical observations
  34. GRB 060526: Multiple Optical Flares
  35. GRB060526: afterglow fitting and probable jet break
  36. GRB 060526: RTT150 optical observations
  37. GRB060526: Optical counterpart from MIRO
  38. GRB060502b: optical observations
  39. GRB 060526: RTT150 optical observations
  40. GRB 060526: Tautenburg OT observation and light curve fitting
  41. GRB060526: optical observations
  42. GRB 060526: SMARTS optical/IR afterglow observations
  43. GRB060526: possible break in the optical light curve
  44. GRB 060526: REM observations
  45. GRB 060526: RTT150 optical observations, afterglow flattening
  46. GRB 060526: Optical Flare
  47. GRB 060526: MDM-2.4m Observations
  48. GRB 060526: Refined analysis of the Swift-BAT burst
  49. GRB 060526: RTT150 optical observations
  50. GRB060526: Further Swift-UVOT Observations
  51. GRB060526, optical observations
  52. GRB 060526: Magellan Redshift
  53. GRB 060526 Lulin optical observation
  54. GRB 060526: Swift/XRT Team refined analysis
  55. GRB 060526: TNG optical observations
  56. GRB 060526: ROTSE-III Observations of Optical Counterpart
  57. GRB 060526: Watcher Observations
  58. GRB060526 - SDSS Pre-burst Observations
  59. GRB 060526: Continued emission for the Swift burst
  60. GRB 060526: Swift detection of a burst with x-ray and optical afterglow
  61. GRB060505: VLT observations of the optical afterglow
  62. GRB 060413 : WIDGET simultaneous optical observations
  63. GRB 060522: Swift/UVOT Observations: Correction
  64. GRB 060522: Swift/UVOT Observations of the Optical Afterglow
  65. XMM-Newton observation of GRB060510b
  66. GRB060512: Late-Time P200 Observations
  67. GRB060522: z = 5.11 Keck-LRIS Redshift
  68. GRB 060522: Swift/XRT Team refined analysis
  69. GRB 060522: Swift-BAT Refined Analysis
  70. GRB 060522: REM NIR observations
  71. GRB 060522: TNG optical observations
  72. GRB 060522: Swift detection of a burst with possible optical afterglow
  73. GRB 060512: reanalysis of optical spectra
  74. GRB 060515: NIR observation
  75. GRB 060210: Jet Break in the XRT light curve
  76. GRB 060516: Refined analysis of the Swift-BAT burst
  77. GRB 060512: TNG optical spectroscopy
  78. GRB 060516: Swift detection of a burst
  79. GRB060515: P200 NIR Observations
  80. GRB 060505 BAT refined analysis
  81. GRB 060515 BAT refined analysis
  82. GRB 060512: TAROT optical observation
  83. GRB 060515: Swift/XRT Team refined analysis
  84. GRB 060515: Swift/UVOT Upper Limits
  85. GRB 060515: Swift/XRT position
  86. GRB 060515: Super-LOTIS Observations
  87. GRB060515: Swift/UVOT initial observation
  88. GRB 060515: TAROT optical observation
  89. GRB 060515: ROTSE-III Optical Limits
  90. GRB 060515: Swift detection of a burst
  91. VLT optical spectroscopy of GRB 060512
  92. Swift/UVOT observations of GRB060512.
  93. GRB 060512: Subaru NIR observation
  94. GRB060512: Swift XRT Team refined analysis
  95. GRB 060512: 1.54m Kuiper Observations
  96. GRB 060512: Detection of NIR afterglow
  97. GRB 060512: P60 Observations
  98. GRB 060512: Swift-BAT Refined Analysis
  99. GRB 060505 - OT candidate + galaxy spectrum
  100. GRB 060512: optical decay

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