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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 050713A : Swift-BAT Refined Analysis
  2. GRB050712: Swift UVOT Observation of Afterglow Emission
  3. GRB 050713A : Lulin R-band observation
  4. GRB 050713A XMM-Newton observation
  5. GRB 050713b : Lulin R-band observations
  6. GRB050713B: Faulkes North Telescope observation
  7. RBO RI observations of GRB 050713A
  8. GRB 050713B
  9. GRB050709 : Chandra source optical counterpart
  10. GRB050713: Liverpool Telescope prompt observations
  11. GRB 050712, optical observations
  12. GRB 050713 : Planned XMM-Newton observation
  13. GRB050709: Candidate X-ray Afterglow from Chandra
  14. GRB 050713, R-band observations at NOT
  15. GRB 050713: ARC NIR Detections and Identification of Fading
  16. GRB050713: possible I-band afterglow
  17. GRB 050713: Swift detection of Bright Burst
  18. GRB 050713A: ROTSE-III Optical Limits
  19. GRB050712: XRT refined analysis
  20. GRB050709: Radio Observations
  21. GRB 050709: Swift UVOT and XRT observations
  22. GRB 050712: Swift-BAT Refined Analysis
  23. GRB050712: UVOT candidate optical counterpart
  24. GRB 050712: Swift XRT afterglow position
  25. GRB 050712: Swift detection of a weak burst
  26. GRB 050709: LCO40 Observations
  27. GRB050709, optical observations
  28. GRB050709: A Possible Short-Hard GRB Localized by HETE
  29. PROMPT Rc Observations of GRB 050709
  30. GRB 050525a: PROMPT VRcIc Detections
  31. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  32. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  33. GRB 050626 optical observations
  34. GRB 050626: Swift XRT observations
  35. GRB 050701
  36. GRB 050701, optical observations
  37. GRB 050408: ARC 3.5-meter NIR Observations
  38. GRB 050701: Refined XRT analysis
  39. Swift UVOT observations of GRB 050701
  40. GRB050701: Swift-BAT Refined analysis
  41. GRB 050701: Swift XRT afterglow position
  42. Swift trigger 143708 is really GRB 050701
  43. GRB 050607, radio observations
  44. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  45. GRB 050626 - Correction to GCN 3552
  46. GRB 050626 - a long GRB detected with INTEGRAL
  47. GRB 050525A: Swift Late-Time Decay Rate
  48. GRB050525a: HST Observations
  49. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  50. H3804: A Possible New XRB Detected by HETE
  51. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  52. XRF 050509c: Optical monitoring
  53. Konus-Wind observation of an intermediate burst from SGR 1806-20
  54. IBAS Alert #2512 is NOT a GRB
  55. XRF050509c: Radio Detection
  56. GRB 050416(a): Host Galaxy Redshift Determination
  57. GRB 050607: MDM Observation
  58. GRB 050607 optical decay
  59. GRB 050607: RTT150 optical observations
  60. GRB050607: refined analysis of prompt REM observations
  61. Swift/UVOT observations of GRB050607
  62. GRB 050607 : Lulin R-band observation
  63. GRB 050607: PROMPT VRcIc Observations
  64. GRB 050607: RAPTOR-S Early Optical Limits
  65. GRB050607: KAIT optical limits
  66. GRB 050525a, Mid-Infrared Observations
  67. GRB 050607: Optical decay and spectral slope
  68. GRB 050607: MDM Observations
  69. GRB050607,optical observation
  70. GRB 050607 - XRT refined data analysis
  71. Optical Afterglow of GRB 050607
  72. GRB050607 optical limit by "Pi of the Sky"
  73. GRB050607: Swift Detection of a long GRB
  74. GRB050607: P60 Observations
  75. GRB050607: prompt REM observations
  76. GRB 050603: prediction of t_break
  77. Limits on a SN in the field of GRB 050509b
  78. GRB 050603: Redshift
  79. GRB 050603 - XRT data analysis of the first day
  80. Konus-Wind observation of GRB 050603
  81. GRB 050603: Analysis of UVOT data
  82. GRB050603: Fading Afterglow observed by Swift UVOT
  83. GRB050603, submillimetre observations
  84. GRB 050603: Swift XRT Position
  85. GRB050603: Radio Detection
  86. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  87. GRB 050603: Afterglow Identification from LCO
  88. GRB 050603: INTEGRAL shows it is not a short GRB
  89. Swift/BAT Detection of GRB050603
  90. GRB 050408: jet break in the XRT light curve
  91. GRB 050525a, infrared observations
  92. GRB 050525a, SMARTS optical/IR afterglow observations
  93. GRB050528, XRT observations
  94. Correction to GCN Circ 3502 on GRB 050528
  95. GRB050528: updated Liverpool Telescope limits
  96. Swift-BAT GRB 050528: a soft burst
  97. Update on Swift-BAT GRB 050528 (Trigger 130679)
  98. GRB050528: BOOTES optical candidate (retraction)
  99. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  100. GRB050528: BOOTES optical candidate

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