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

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