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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: Swift XRT refined analysis
  2. XRF050509C: Chandra Afterglow Detection
  3. XRF 050509c: Swift XRT Upper Limit
  4. XRF050509c: Radio Observations
  5. RBO Observations of GRB050520
  6. GRB 050520: P200 Observations
  7. GRB050520: Liverpool Telescope follow-up
  8. RBO Observations of GRB050520
  9. GRB 050520: TAROT optical limit
  10. GRB 050520: Swift XRT position
  11. GRB 050520: VLT/ULTRACAM observations
  12. GRB 050520: OSN optical observations
  13. GRB 050520: BART optical limit
  14. GRB 050520 - A long GRB detected with INTEGRAL
  15. No Swift-BAT Lightcurves in real-time for next 3 weeks
  16. Swift-BAT trigger 122203 is not a real GRB
  17. XRF 050509C: REM NIR and Optical refined analysis
  18. GRB 050504: Swift XRT afterglow candidate has faded
  19. XRF 050509c optical afterglow
  20. GRB 050509B and short GRB-SN association? (corrected)
  21. GRB 050509B and short GRB-SN association?
  22. GRB 050509B: Subaru Optical Observations
  23. GRB050502b: Early Observation
  24. GRB050509b, Bok telescope B-band imaging
  25. Refined Chandra analysis of GRB 050509b
  26. GRB050509b, SDSS pre-burst observations
  27. GRB 050509b: Keck/Chandra Cross-Correlation
  28. GRB 050509b: Keck/Chandra Cross-Correlation
  29. Chandra observation of GRB 050509b
  30. GRB 050509b: RAPTOR deep, early limits.
  31. GRB050509B: Optical/Infared observations
  32. GRB 050509b: Swift/UVOT follow-up measurements
  33. GRB 050509b Milagro GeV/TeV Observations
  34. GRB050509B: Optical observations at the Very Large Telescope
  35. GRB 050509b: No Optical Variability in XRT Error Circle
  36. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  37. GRB 050509a: Swift-BAT refined analysis
  38. GRB 050509c: ROTSE-III Optical Limits
  39. GRB 050509B: WSRT Radio Observations
  40. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  41. GRB 050505, early TAROT observation
  42. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  43. GRB 050509b: Further Analysis of Keck LRIS Images
  44. GRB050509c: REM NIR and Optical observations
  45. GRB 050509b: Physical Properties of the Candidate Host galaxy
  46. GRB 050505: SARA Observations
  47. Swift UVOT Follow-up Observations of GRB 050509B
  48. GRB 050509B, Optical Observations
  49. GRB 050509B: Swift/XRT refined analysis
  50. GRB050509a: Swift UVOT observations
  51. GRB 050509b: Optical observations
  52. GRB 050509b: Precision Astrometry
  53. GRB 050509b: Possible Optical Counterpart
  54. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  55. GRB 050509A: Optical observations
  56. GRB 050509b: Optical Counterpart Candidate
  57. GRB050509b: Radio Observations
  58. GRB 050509b: PAIRITEL and WIYN Observations
  59. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  60. GRB 050509b: optical observations
  61. GRB 050509b: Swift XRT Position
  62. GRB 050509B: ROTSE-III Optical Limits
  63. Swift Detection of GRB050509b: A short duration burst
  64. GRB 050509a: Swift XRT Position
  65. Swift Detection of the Burst GRB050509
  66. Swift-BAT detection of GRB 050507
  67. GRB 050505: Keck I-band Magnitude
  68. GRB 050505: early time observations
  69. GRB 050505 - Faulkes Telescope North observations
  70. GRB 050502a: Swift XRT Upper Limit
  71. GRB 050505, simultaneous optical observation
  72. GRB050505: Infrared observations
  73. GRB 050505: Further Swift UVOT observations.
  74. GRB050505: AAVSO observations
  75. GRB050416A : 1 GHz limit from GMRT
  76. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  77. GRB 050505 UVOT
  78. GRB050505: Optical Afterglow Candidate
  79. GRB 050505: Swift XRT Position
  80. GRB050505 Swift-BAT refined analysis
  81. GRB 050502a: Optical Observations
  82. GRB 050416b:Swift XRT afterglow upper limits
  83. GRB 050416b:Swift XRT afterglow upper limits
  84. Swift-BAT detection of GRB050505
  85. GRB 050504: Swift XRT position
  86. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  87. GRB050502b: Afterglow Confirmation
  88. GRB050502: P200 Observations (Correction)
  89. GRB050502: P200 Observations
  90. GRB 050504 : R band observation at Lulin observatory
  91. Swift UVOT observation of GRB 050504
  92. GRB 050504, R band Observations
  93. GRB050504: Faulkes North optical robotic limit
  94. GRB 050502b, V band Observations
  95. GRB050504: P60 Observations
  96. GRB 050504: A long GRB detected with INTEGRAL
  97. GRB (?) 050504: IR Observations, Intriguing Source
  98. GRB 050502b, Optical observations
  99. GRB050502a: P60 Observations (Correction)
  100. GRB050502a: P60 Observations

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