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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 050520: TAROT optical limit
  2. GRB 050520: Swift XRT position
  3. GRB 050520: VLT/ULTRACAM observations
  4. GRB 050520: OSN optical observations
  5. GRB 050520: BART optical limit
  6. GRB 050520 - A long GRB detected with INTEGRAL
  7. No Swift-BAT Lightcurves in real-time for next 3 weeks
  8. Swift-BAT trigger 122203 is not a real GRB
  9. XRF 050509C: REM NIR and Optical refined analysis
  10. GRB 050504: Swift XRT afterglow candidate has faded
  11. XRF 050509c optical afterglow
  12. GRB 050509B and short GRB-SN association? (corrected)
  13. GRB 050509B and short GRB-SN association?
  14. GRB 050509B: Subaru Optical Observations
  15. GRB050502b: Early Observation
  16. GRB050509b, Bok telescope B-band imaging
  17. Refined Chandra analysis of GRB 050509b
  18. GRB050509b, SDSS pre-burst observations
  19. GRB 050509b: Keck/Chandra Cross-Correlation
  20. GRB 050509b: Keck/Chandra Cross-Correlation
  21. Chandra observation of GRB 050509b
  22. GRB 050509b: RAPTOR deep, early limits.
  23. GRB050509B: Optical/Infared observations
  24. GRB 050509b: Swift/UVOT follow-up measurements
  25. GRB 050509b Milagro GeV/TeV Observations
  26. GRB050509B: Optical observations at the Very Large Telescope
  27. GRB 050509b: No Optical Variability in XRT Error Circle
  28. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  29. GRB 050509a: Swift-BAT refined analysis
  30. GRB 050509c: ROTSE-III Optical Limits
  31. GRB 050509B: WSRT Radio Observations
  32. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  33. GRB 050505, early TAROT observation
  34. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  35. GRB 050509b: Further Analysis of Keck LRIS Images
  36. GRB050509c: REM NIR and Optical observations
  37. GRB 050509b: Physical Properties of the Candidate Host galaxy
  38. GRB 050505: SARA Observations
  39. Swift UVOT Follow-up Observations of GRB 050509B
  40. GRB 050509B, Optical Observations
  41. GRB 050509B: Swift/XRT refined analysis
  42. GRB050509a: Swift UVOT observations
  43. GRB 050509b: Optical observations
  44. GRB 050509b: Precision Astrometry
  45. GRB 050509b: Possible Optical Counterpart
  46. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  47. GRB 050509A: Optical observations
  48. GRB 050509b: Optical Counterpart Candidate
  49. GRB050509b: Radio Observations
  50. GRB 050509b: PAIRITEL and WIYN Observations
  51. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  52. GRB 050509b: optical observations
  53. GRB 050509b: Swift XRT Position
  54. GRB 050509B: ROTSE-III Optical Limits
  55. Swift Detection of GRB050509b: A short duration burst
  56. GRB 050509a: Swift XRT Position
  57. Swift Detection of the Burst GRB050509
  58. Swift-BAT detection of GRB 050507
  59. GRB 050505: Keck I-band Magnitude
  60. GRB 050505: early time observations
  61. GRB 050505 - Faulkes Telescope North observations
  62. GRB 050502a: Swift XRT Upper Limit
  63. GRB 050505, simultaneous optical observation
  64. GRB050505: Infrared observations
  65. GRB 050505: Further Swift UVOT observations.
  66. GRB050505: AAVSO observations
  67. GRB050416A : 1 GHz limit from GMRT
  68. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  69. GRB 050505 UVOT
  70. GRB050505: Optical Afterglow Candidate
  71. GRB 050505: Swift XRT Position
  72. GRB050505 Swift-BAT refined analysis
  73. GRB 050502a: Optical Observations
  74. GRB 050416b:Swift XRT afterglow upper limits
  75. GRB 050416b:Swift XRT afterglow upper limits
  76. Swift-BAT detection of GRB050505
  77. GRB 050504: Swift XRT position
  78. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  79. GRB050502b: Afterglow Confirmation
  80. GRB050502: P200 Observations (Correction)
  81. GRB050502: P200 Observations
  82. GRB 050504 : R band observation at Lulin observatory
  83. Swift UVOT observation of GRB 050504
  84. GRB 050504, R band Observations
  85. GRB050504: Faulkes North optical robotic limit
  86. GRB 050502b, V band Observations
  87. GRB050504: P60 Observations
  88. GRB 050504: A long GRB detected with INTEGRAL
  89. GRB (?) 050504: IR Observations, Intriguing Source
  90. GRB 050502b, Optical observations
  91. GRB050502a: P60 Observations (Correction)
  92. GRB050502a: P60 Observations
  93. Renewal of SGR 1806-20 activity
  94. GRB 050502a: RBO Observations
  95. GRB 050502A: WSRT Radio Observations
  96. GRB050502A: Optical Observations
  97. GRB050502B Swift-BAT refined analysis
  98. GRB050502B: I band source in XRT error circle
  99. Swift UVOT refined analysis
  100. Retraction of Swift-BAT trigger 116145

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