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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"

28068 results found.

  1. XRF 050522: Swift XRT observation
  2. XRF050522, BVRcIc field photometry
  3. XRF050522: Optical Observations
  4. XRF050522: Near-infrared Observations
  5. GRB 050520: VLT/ULTRACAM observations
  6. Swift UVOT Observations of GRB 050520
  7. GRB 050520: Swift XRT refined analysis
  8. XRF050509C: Chandra Afterglow Detection
  9. XRF 050509c: Swift XRT Upper Limit
  10. RBO Observations of GRB050520
  11. GRB 050520: P200 Observations
  12. GRB050520: Liverpool Telescope follow-up
  13. GRB 050520: TAROT optical limit
  14. GRB 050520: Swift XRT position
  15. GRB 050520: OSN optical observations
  16. XRF 050509C: REM NIR and Optical refined analysis
  17. GRB 050504: Swift XRT afterglow candidate has faded
  18. XRF 050509c optical afterglow
  19. GRB 050509B and short GRB-SN association? (corrected)
  20. GRB 050509B and short GRB-SN association?
  21. GRB 050509B: Subaru Optical Observations
  22. GRB050502b: Early Observation
  23. GRB050509b, Bok telescope B-band imaging
  24. Refined Chandra analysis of GRB 050509b
  25. GRB050509b, SDSS pre-burst observations
  26. GRB 050509b: Keck/Chandra Cross-Correlation
  27. GRB 050509b: Keck/Chandra Cross-Correlation
  28. Chandra observation of GRB 050509b
  29. GRB 050509b: RAPTOR deep, early limits.
  30. GRB050509B: Optical/Infared observations
  31. GRB 050509b: Swift/UVOT follow-up measurements
  32. GRB 050509b Milagro GeV/TeV Observations
  33. GRB050509B: Optical observations at the Very Large Telescope
  34. GRB 050509b: No Optical Variability in XRT Error Circle
  35. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  36. GRB 050509a: Swift-BAT refined analysis
  37. GRB 050509B: WSRT Radio Observations
  38. GRB 050505: SARA Observations
  39. Swift UVOT Follow-up Observations of GRB 050509B
  40. GRB 050509B, Optical Observations
  41. GRB 050509B: Swift/XRT refined analysis
  42. GRB050509a: Swift UVOT observations
  43. GRB 050509b: Optical observations
  44. GRB 050509b: Precision Astrometry
  45. GRB 050509b: Possible Optical Counterpart
  46. GRB 050509A: Optical observations
  47. GRB 050509b: Optical Counterpart Candidate
  48. GRB050509b: Radio Observations
  49. GRB 050509b: PAIRITEL and WIYN Observations
  50. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  51. GRB 050509b: optical observations
  52. GRB 050509b: Swift XRT Position
  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 050502a: Swift XRT Upper Limit
  60. GRB 050505: Further Swift UVOT observations.
  61. GRB050505: AAVSO observations
  62. GRB050416A : 1 GHz limit from GMRT
  63. GRB 050505 UVOT
  64. GRB050505: Optical Afterglow Candidate
  65. GRB 050505: Swift XRT Position
  66. GRB 050502a: Optical Observations
  67. GRB 050416b:Swift XRT afterglow upper limits
  68. GRB 050416b:Swift XRT afterglow upper limits
  69. Swift-BAT detection of GRB050505
  70. GRB 050504: Swift XRT position
  71. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  72. GRB050502b: Afterglow Confirmation
  73. GRB050502: P200 Observations (Correction)
  74. GRB050502: P200 Observations
  75. GRB050502a: P60 Observations (Correction)
  76. GRB050502a: P60 Observations
  77. GRB 050502a: RBO Observations
  78. GRB 050502A: WSRT Radio Observations
  79. GRB050502A: Optical Observations
  80. GRB050502B Swift-BAT refined analysis
  81. GRB050502B: I band source in XRT error circle
  82. Swift UVOT refined analysis
  83. GRB 050502a : R band observation at Lulin observatory
  84. GRB 050502b : optical observation at Lulin observatory
  85. GRB 050502b: Swift XRT Position
  86. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  87. Swift Detection of the Bright Burst GRB050502b
  88. GRB 050502: Confirmed variability of the afterglow candidate +
  89. GRB 050502: PAIRITEL IR Observations
  90. GRB 050502: ROTSE-III Detection of Possible Counterpart
  91. Swift-BAT Trigger 115881 is not a real GRB
  92. Swift/BAT possible detection of a weak burst GRB050430
  93. GRB 050401: Rc observation
  94. GRB050416a: Radio Detection
  95. GRB 050422: Swift-UVOT observation
  96. GRB 050422: Swift XRT Position
  97. Swift Detection of GRB 050422
  98. GRB 050421: NIR observations
  99. GRB 050416: Optical/NIR observations
  100. GRB 050421: Further Analysis of IR imaging

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