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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"

21392 results found.

  1. GRB 050525A: Swift-BAT refined analysis
  2. Swift/UVOT UV and optical detections of GRB 050525
  3. Konus-Wind observation of GRB 050525
  4. GRB 050525: TAROT observations of the early afterglow
  5. INTEGRAL detection of GRB 050525
  6. GRB 050525: Optical observation
  7. GRB050525: ROTSE-III Refined Analysis
  8. GRB 050525 - Very Bright, Not Short
  9. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  10. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  11. XRF050522: NIR observations of XRT candidate
  12. XRF 050522: Swift XRT refined analysis
  13. Swift/UVOT observation of XRF 050522
  14. GRB 050509A: Further I-band imaging
  15. RBO Observations of GRB050522
  16. GRB050509b: optical observations
  17. GRB050520: Radio Observations
  18. XRF 050522: Swift XRT observation
  19. GRB 050520: VLT/ULTRACAM observations
  20. Swift UVOT Observations of GRB 050520
  21. GRB 050520: Swift XRT refined analysis
  22. XRF050509C: Chandra Afterglow Detection
  23. XRF 050509c: Swift XRT Upper Limit
  24. RBO Observations of GRB050520
  25. GRB 050520: P200 Observations
  26. GRB050520: Liverpool Telescope follow-up
  27. GRB 050520: TAROT optical limit
  28. GRB 050520: Swift XRT position
  29. No Swift-BAT Lightcurves in real-time for next 3 weeks
  30. Swift-BAT trigger 122203 is not a real GRB
  31. GRB 050504: Swift XRT afterglow candidate has faded
  32. GRB 050509B and short GRB-SN association? (corrected)
  33. GRB 050509B and short GRB-SN association?
  34. GRB 050509B: Subaru Optical Observations
  35. GRB050502b: Early Observation
  36. GRB050509b, Bok telescope B-band imaging
  37. Refined Chandra analysis of GRB 050509b
  38. GRB050509b, SDSS pre-burst observations
  39. GRB 050509b: Keck/Chandra Cross-Correlation
  40. GRB 050509b: Keck/Chandra Cross-Correlation
  41. Chandra observation of GRB 050509b
  42. GRB 050509b: RAPTOR deep, early limits.
  43. GRB050509B: Optical/Infared observations
  44. GRB 050509b: Swift/UVOT follow-up measurements
  45. GRB 050509b Milagro GeV/TeV Observations
  46. GRB050509B: Optical observations at the Very Large Telescope
  47. GRB 050509b: No Optical Variability in XRT Error Circle
  48. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  49. GRB 050509a: Swift-BAT refined analysis
  50. GRB 050509B: WSRT Radio Observations
  51. GRB 050505: SARA Observations
  52. Swift UVOT Follow-up Observations of GRB 050509B
  53. GRB 050509B, Optical Observations
  54. GRB 050509B: Swift/XRT refined analysis
  55. GRB050509a: Swift UVOT observations
  56. GRB 050509b: Optical observations
  57. GRB 050509b: Precision Astrometry
  58. GRB 050509b: Possible Optical Counterpart
  59. GRB 050509A: Optical observations
  60. GRB 050509b: Optical Counterpart Candidate
  61. GRB050509b: Radio Observations
  62. GRB 050509b: PAIRITEL and WIYN Observations
  63. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  64. GRB 050509b: optical observations
  65. GRB 050509b: Swift XRT Position
  66. GRB 050509B: ROTSE-III Optical Limits
  67. Swift Detection of GRB050509b: A short duration burst
  68. GRB 050509a: Swift XRT Position
  69. Swift Detection of the Burst GRB050509
  70. Swift-BAT detection of GRB 050507
  71. GRB 050505: early time observations
  72. GRB 050505 - Faulkes Telescope North observations
  73. GRB 050502a: Swift XRT Upper Limit
  74. GRB 050505, simultaneous optical observation
  75. GRB 050505: Further Swift UVOT observations.
  76. GRB050416A : 1 GHz limit from GMRT
  77. GRB 050505 UVOT
  78. GRB050505: Optical Afterglow Candidate
  79. GRB 050505: Swift XRT Position
  80. GRB050505 Swift-BAT refined analysis
  81. GRB 050416b:Swift XRT afterglow upper limits
  82. GRB 050416b:Swift XRT afterglow upper limits
  83. Swift-BAT detection of GRB050505
  84. GRB 050504: Swift XRT position
  85. Swift UVOT observation of GRB 050504
  86. GRB 050502b, V band Observations
  87. GRB050502B Swift-BAT refined analysis
  88. GRB050502B: I band source in XRT error circle
  89. Swift UVOT refined analysis
  90. Retraction of Swift-BAT trigger 116145
  91. GRB 050502b : optical observation at Lulin observatory
  92. GRB 050502b: Swift XRT Position
  93. GRB050502B: Optical Limits from ANU 1m
  94. Swift Detection of the Bright Burst GRB050502b
  95. GRB050502: ANU 1m optical Observations
  96. Swift-BAT Trigger 115881 is not a real GRB
  97. Swift/BAT possible detection of a weak burst GRB050430
  98. GRB 050401: Rc observation
  99. GRB050416a: Radio Detection
  100. GRB 050422: Swift-UVOT observation

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