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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. Refined Chandra analysis of GRB 050509b
  2. GRB050509b, SDSS pre-burst observations
  3. GRB 050509b: Keck/Chandra Cross-Correlation
  4. GRB 050509b: Keck/Chandra Cross-Correlation
  5. Chandra observation of GRB 050509b
  6. GRB 050509b: RAPTOR deep, early limits.
  7. GRB050509B: Optical/Infared observations
  8. GRB 050509b: Swift/UVOT follow-up measurements
  9. GRB 050509b Milagro GeV/TeV Observations
  10. GRB050509B: Optical observations at the Very Large Telescope
  11. GRB 050509b: No Optical Variability in XRT Error Circle
  12. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  13. GRB 050509a: Swift-BAT refined analysis
  14. GRB 050509c: ROTSE-III Optical Limits
  15. GRB 050509B: WSRT Radio Observations
  16. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  17. GRB 050505, early TAROT observation
  18. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  19. GRB 050509b: Further Analysis of Keck LRIS Images
  20. GRB050509c: REM NIR and Optical observations
  21. GRB 050509b: Physical Properties of the Candidate Host galaxy
  22. GRB 050505: SARA Observations
  23. Swift UVOT Follow-up Observations of GRB 050509B
  24. GRB 050509B, Optical Observations
  25. GRB 050509B: Swift/XRT refined analysis
  26. GRB050509a: Swift UVOT observations
  27. GRB 050509b: Optical observations
  28. GRB 050509b: Precision Astrometry
  29. GRB 050509b: Possible Optical Counterpart
  30. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  31. GRB 050509A: Optical observations
  32. GRB 050509b: Optical Counterpart Candidate
  33. GRB050509b: Radio Observations
  34. GRB 050509b: PAIRITEL and WIYN Observations
  35. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  36. GRB 050509b: optical observations
  37. GRB 050509b: Swift XRT Position
  38. GRB 050509B: ROTSE-III Optical Limits
  39. Swift Detection of GRB050509b: A short duration burst
  40. GRB 050509a: Swift XRT Position
  41. Swift Detection of the Burst GRB050509
  42. Swift-BAT detection of GRB 050507
  43. GRB 050505: Keck I-band Magnitude
  44. GRB 050505: early time observations
  45. GRB 050505 - Faulkes Telescope North observations
  46. GRB 050502a: Swift XRT Upper Limit
  47. GRB 050505, simultaneous optical observation
  48. GRB050505: Infrared observations
  49. GRB 050505: Further Swift UVOT observations.
  50. GRB050505: AAVSO observations
  51. GRB050416A : 1 GHz limit from GMRT
  52. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  53. GRB 050505 UVOT
  54. GRB050505: Optical Afterglow Candidate
  55. GRB 050505: Swift XRT Position
  56. GRB050505 Swift-BAT refined analysis
  57. GRB 050502a: Optical Observations
  58. GRB 050416b:Swift XRT afterglow upper limits
  59. GRB 050416b:Swift XRT afterglow upper limits
  60. Swift-BAT detection of GRB050505
  61. GRB 050504: Swift XRT position
  62. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  63. GRB050502b: Afterglow Confirmation
  64. GRB050502: P200 Observations (Correction)
  65. GRB050502: P200 Observations
  66. GRB 050504 : R band observation at Lulin observatory
  67. Swift UVOT observation of GRB 050504
  68. GRB 050504, R band Observations
  69. GRB050504: Faulkes North optical robotic limit
  70. GRB 050502b, V band Observations
  71. GRB050504: P60 Observations
  72. GRB 050504: A long GRB detected with INTEGRAL
  73. GRB (?) 050504: IR Observations, Intriguing Source
  74. GRB 050502b, Optical observations
  75. GRB050502a: P60 Observations (Correction)
  76. GRB050502a: P60 Observations
  77. Renewal of SGR 1806-20 activity
  78. GRB 050502a: RBO Observations
  79. GRB 050502A: WSRT Radio Observations
  80. GRB050502A: Optical Observations
  81. GRB050502B Swift-BAT refined analysis
  82. GRB050502B: I band source in XRT error circle
  83. Swift UVOT refined analysis
  84. Retraction of Swift-BAT trigger 116145
  85. GRB 050502a : R band observation at Lulin observatory
  86. GRB 050502b : optical observation at Lulin observatory
  87. GRB 050502b: Swift XRT Position
  88. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  89. GRB050502B: Optical Limits from ANU 1m
  90. Swift Detection of the Bright Burst GRB050502b
  91. GRB 050502: INTEGRAL results
  92. GRB050502: ANU 1m optical Observations
  93. GRB 050502: Confirmed variability of the afterglow candidate +
  94. GRB 050502: PAIRITEL IR Observations
  95. GRB050502 - Correction on the Optical Candidate from the Liverpool
  96. GRB050502 - Optical Candidate from the Liverpool Telescope
  97. GRB 050502 - A long GRB detected with INTEGRAL
  98. GRB 050502: ROTSE-III Detection of Possible Counterpart
  99. Swift-BAT Trigger 115881 is not a real GRB
  100. Swift/BAT possible detection of a weak burst GRB050430

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