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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 051227 : WIDGET simultaneous optical observations
  2. GRB 051028 : WIDGET pre-trigger limit
  3. GRB 060526: RTT150 optical observations
  4. GRB 060526: Multiple Optical Flares
  5. GRB060526: afterglow fitting and probable jet break
  6. GRB 060526: RTT150 optical observations
  7. GRB060526: Optical counterpart from MIRO
  8. GRB060502b: optical observations
  9. GRB 060526: RTT150 optical observations
  10. GRB 060526: Tautenburg OT observation and light curve fitting
  11. GRB060526: optical observations
  12. GRB 060526: SMARTS optical/IR afterglow observations
  13. GRB060526: possible break in the optical light curve
  14. GRB 060526: REM observations
  15. GRB 060526: RTT150 optical observations, afterglow flattening
  16. GRB 060526: Optical Flare
  17. GRB 060526: MDM-2.4m Observations
  18. GRB 060526: Refined analysis of the Swift-BAT burst
  19. GRB 060526: RTT150 optical observations
  20. GRB060526: Further Swift-UVOT Observations
  21. GRB060526, optical observations
  22. GRB 060526: Magellan Redshift
  23. GRB 060526 Lulin optical observation
  24. GRB 060526: Swift/XRT Team refined analysis
  25. GRB 060526: TNG optical observations
  26. GRB 060526: ROTSE-III Observations of Optical Counterpart
  27. GRB 060526: Watcher Observations
  28. GRB060526 - SDSS Pre-burst Observations
  29. GRB 060526: Continued emission for the Swift burst
  30. GRB 060526: Swift detection of a burst with x-ray and optical afterglow
  31. GRB060505: VLT observations of the optical afterglow
  32. GRB 060413 : WIDGET simultaneous optical observations
  33. GRB 060522: Swift/UVOT Observations: Correction
  34. GRB 060522: Swift/UVOT Observations of the Optical Afterglow
  35. XMM-Newton observation of GRB060510b
  36. GRB060512: Late-Time P200 Observations
  37. GRB060522: z = 5.11 Keck-LRIS Redshift
  38. GRB 060522: Swift/XRT Team refined analysis
  39. GRB 060522: Swift-BAT Refined Analysis
  40. GRB 060522: REM NIR observations
  41. GRB 060522: TNG optical observations
  42. GRB 060522: Swift detection of a burst with possible optical afterglow
  43. GRB 060512: reanalysis of optical spectra
  44. GRB 060515: NIR observation
  45. GRB 060210: Jet Break in the XRT light curve
  46. GRB 060516: Refined analysis of the Swift-BAT burst
  47. GRB 060512: TNG optical spectroscopy
  48. GRB 060516: Swift detection of a burst
  49. GRB060515: P200 NIR Observations
  50. GRB 060505 BAT refined analysis
  51. GRB 060515 BAT refined analysis
  52. GRB 060512: TAROT optical observation
  53. GRB 060515: Swift/XRT Team refined analysis
  54. GRB 060515: Swift/UVOT Upper Limits
  55. GRB 060515: Swift/XRT position
  56. GRB 060515: Super-LOTIS Observations
  57. GRB060515: Swift/UVOT initial observation
  58. GRB 060515: TAROT optical observation
  59. GRB 060515: ROTSE-III Optical Limits
  60. GRB 060515: Swift detection of a burst
  61. VLT optical spectroscopy of GRB 060512
  62. Swift/UVOT observations of GRB060512.
  63. GRB 060512: Subaru NIR observation
  64. GRB060512: Swift XRT Team refined analysis
  65. GRB 060512: 1.54m Kuiper Observations
  66. GRB 060512: Detection of NIR afterglow
  67. GRB 060512: P60 Observations
  68. GRB 060512: Swift-BAT Refined Analysis
  69. GRB 060505 - OT candidate + galaxy spectrum
  70. GRB 060512: optical decay
  71. GRB 060512: REM NIR observations
  72. GRB060512 - SDSS Pre-Burst Observations
  73. GRB060512 Name Correction: LT Afterglow detection
  74. GRB060512: Liverpool Telescope Afterglow detection
  75. GRB 060512: Swift detection of a burst with an optical afterglow
  76. GRB 060510A: Swift/UVOT Detection of an Optical Afterglow
  77. GRB 060505: X-ray afterglow - Correction -
  78. GRB 060505: X-ray afterglow
  79. Konus-Wind observation of GRB 060510A
  80. GRB060418: optical observations
  81. GRB 060428a, SMARTS optical/IR afterglow detection
  82. GRB060510B: Swift XRT refined analysis
  83. GRB 060510B: Swift/UVOT Upper Limits
  84. GRB 060510A: Refined analysis of the Swift-BAT burst
  85. GRB 060510B: Swift-BAT Refined Analysis
  86. GRB060510A: XRT refined analysis
  87. GRB060510 - SDSS Pre-Burst Observations
  88. GRB 060510b: Redshift
  89. GRB060510B : Faulkes North Telescope detection
  90. GRB 060510B : Planned XMM-Newton observation
  91. GRB 060510b: Gemini NIR observations
  92. GRB 060510B: Super-LOTIS Observations
  93. GRB 060510b: NIR observations
  94. GRB 060510B: Coordinate correction
  95. GRB 060510B: MDM Observations and candidate OT
  96. GRB 060510B: Swift detection of a burst
  97. GRB 060510: Swift detection of a burst with optical transient
  98. GRB060507: optical afterglow detection
  99. GRB060502B: improvement in the XRT afterglow position
  100. GRB 060507: BART limit

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