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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. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  2. GRB 050509b: Further Analysis of Keck LRIS Images
  3. GRB050509c: REM NIR and Optical observations
  4. GRB 050509b: Physical Properties of the Candidate Host galaxy
  5. GRB 050505: SARA Observations
  6. Swift UVOT Follow-up Observations of GRB 050509B
  7. GRB 050509B, Optical Observations
  8. GRB 050509B: Swift/XRT refined analysis
  9. GRB050509a: Swift UVOT observations
  10. GRB 050509b: Optical observations
  11. GRB 050509b: Precision Astrometry
  12. GRB 050509b: Possible Optical Counterpart
  13. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  14. GRB 050509A: Optical observations
  15. GRB 050509b: Optical Counterpart Candidate
  16. GRB050509b: Radio Observations
  17. GRB 050509b: PAIRITEL and WIYN Observations
  18. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  19. GRB 050509b: optical observations
  20. GRB 050509b: Swift XRT Position
  21. GRB 050509B: ROTSE-III Optical Limits
  22. Swift Detection of GRB050509b: A short duration burst
  23. GRB 050509a: Swift XRT Position
  24. Swift Detection of the Burst GRB050509
  25. Swift-BAT detection of GRB 050507
  26. GRB 050505: Keck I-band Magnitude
  27. GRB 050505: early time observations
  28. GRB 050505 - Faulkes Telescope North observations
  29. GRB 050502a: Swift XRT Upper Limit
  30. GRB 050505, simultaneous optical observation
  31. GRB050505: Infrared observations
  32. GRB 050505: Further Swift UVOT observations.
  33. GRB050505: AAVSO observations
  34. GRB050416A : 1 GHz limit from GMRT
  35. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  36. GRB 050505 UVOT
  37. GRB050505: Optical Afterglow Candidate
  38. GRB 050505: Swift XRT Position
  39. GRB050505 Swift-BAT refined analysis
  40. GRB 050502a: Optical Observations
  41. GRB 050416b:Swift XRT afterglow upper limits
  42. GRB 050416b:Swift XRT afterglow upper limits
  43. Swift-BAT detection of GRB050505
  44. GRB 050504: Swift XRT position
  45. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  46. GRB050502b: Afterglow Confirmation
  47. GRB050502: P200 Observations (Correction)
  48. GRB050502: P200 Observations
  49. GRB 050504 : R band observation at Lulin observatory
  50. Swift UVOT observation of GRB 050504
  51. GRB 050504, R band Observations
  52. GRB050504: Faulkes North optical robotic limit
  53. GRB 050502b, V band Observations
  54. GRB050504: P60 Observations
  55. GRB 050504: A long GRB detected with INTEGRAL
  56. GRB (?) 050504: IR Observations, Intriguing Source
  57. GRB 050502b, Optical observations
  58. GRB050502a: P60 Observations (Correction)
  59. GRB050502a: P60 Observations
  60. Renewal of SGR 1806-20 activity
  61. GRB 050502a: RBO Observations
  62. GRB 050502A: WSRT Radio Observations
  63. GRB050502A: Optical Observations
  64. GRB050502B Swift-BAT refined analysis
  65. GRB050502B: I band source in XRT error circle
  66. Swift UVOT refined analysis
  67. Retraction of Swift-BAT trigger 116145
  68. GRB 050502a : R band observation at Lulin observatory
  69. GRB 050502b : optical observation at Lulin observatory
  70. GRB 050502b: Swift XRT Position
  71. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  72. GRB050502B: Optical Limits from ANU 1m
  73. Swift Detection of the Bright Burst GRB050502b
  74. GRB 050502: INTEGRAL results
  75. GRB050502: ANU 1m optical Observations
  76. GRB 050502: Confirmed variability of the afterglow candidate +
  77. GRB 050502: PAIRITEL IR Observations
  78. GRB050502 - Correction on the Optical Candidate from the Liverpool
  79. GRB050502 - Optical Candidate from the Liverpool Telescope
  80. GRB 050502 - A long GRB detected with INTEGRAL
  81. GRB 050502: ROTSE-III Detection of Possible Counterpart
  82. Swift-BAT Trigger 115881 is not a real GRB
  83. Swift/BAT possible detection of a weak burst GRB050430
  84. GRB 050401: Rc observation
  85. GRB050416a: Radio Detection
  86. GRB 050422: Swift-UVOT observation
  87. GRB 050422: Swift-BAT refined analysis
  88. GRB 050422: Swift XRT Position
  89. Swift Detection of GRB 050422
  90. GRB 050421: NIR observations
  91. GRB 050416: Optical/NIR observations
  92. GRB 050421: SLOTIS observations
  93. GRB 050421: Further Analysis of IR imaging
  94. GRB050421: Radio Observations
  95. GRB050421: Radio Observations
  96. GRB 050421: Swift-UVOT observation
  97. GRB 050421: IR Observations
  98. GRB 050421: Swift-BAT refined analysis
  99. GRB 050421: ROTSE-III Optical Limits
  100. GRB 050421: NIR observations re-examination

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