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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"

23417 results found.

  1. GRB050502b: Early Observation
  2. GRB050509b, Bok telescope B-band imaging
  3. GRB050509b, SDSS pre-burst observations
  4. GRB 050509b: Keck/Chandra Cross-Correlation
  5. GRB 050509b: Keck/Chandra Cross-Correlation
  6. Chandra observation of GRB 050509b
  7. GRB 050509b: Swift/UVOT follow-up measurements
  8. GRB050509B: Optical observations at the Very Large Telescope
  9. GRB 050509b: No Optical Variability in XRT Error Circle
  10. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  11. GRB 050509c: ROTSE-III Optical Limits
  12. GRB 050509B: WSRT Radio Observations
  13. GRB 050505, early TAROT observation
  14. GRB050509c: REM NIR and Optical observations
  15. GRB 050505: SARA Observations
  16. GRB 050509B: Swift/XRT refined analysis
  17. GRB 050509b: Optical observations
  18. GRB 050509b: Possible Optical Counterpart
  19. GRB 050509A: Optical observations
  20. GRB050509b: Radio Observations
  21. GRB 050509B: ROTSE-III Optical Limits
  22. Swift Detection of GRB050509b: A short duration burst
  23. Swift Detection of the Burst GRB050509
  24. Swift-BAT detection of GRB 050507
  25. GRB 050502a: Swift XRT Upper Limit
  26. GRB 050505, simultaneous optical observation
  27. GRB 050505: Further Swift UVOT observations.
  28. GRB050505: AAVSO observations
  29. GRB050416A : 1 GHz limit from GMRT
  30. GRB050505: Optical Afterglow Candidate
  31. GRB050505 Swift-BAT refined analysis
  32. GRB 050416b:Swift XRT afterglow upper limits
  33. GRB 050416b:Swift XRT afterglow upper limits
  34. Swift-BAT detection of GRB050505
  35. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  36. GRB050502b: Afterglow Confirmation
  37. GRB050502: P200 Observations (Correction)
  38. GRB050502: P200 Observations
  39. Swift UVOT observation of GRB 050504
  40. GRB050504: P60 Observations
  41. GRB (?) 050504: IR Observations, Intriguing Source
  42. GRB 050502b, Optical observations
  43. GRB050502a: P60 Observations (Correction)
  44. GRB050502a: P60 Observations
  45. GRB 050502A: WSRT Radio Observations
  46. GRB050502A: Optical Observations
  47. GRB050502B Swift-BAT refined analysis
  48. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  49. Swift Detection of the Bright Burst GRB050502b
  50. GRB050502 - Optical Candidate from the Liverpool Telescope
  51. GRB 050502: ROTSE-III Detection of Possible Counterpart
  52. Swift/BAT possible detection of a weak burst GRB050430
  53. GRB050416a: Radio Detection
  54. GRB 050422: Swift-BAT refined analysis
  55. Swift Detection of GRB 050422
  56. GRB 050421: SLOTIS observations
  57. GRB 050421: Further Analysis of IR imaging
  58. GRB050421: Radio Observations
  59. GRB050421: Radio Observations
  60. GRB 050421: IR Observations
  61. GRB 050421: ROTSE-III Optical Limits
  62. GRB 050421: NIR observations re-examination
  63. GRB050421
  64. GRB 050421: early Swift XRT analysis results
  65. GRB 050421: NIR observations
  66. GRB050421: P60 Observations
  67. GRB 050421: BOOTES-2 simultaneous optical observations
  68. Swift Detection of GRB050421
  69. GRB 050416b: Tentative Swift XRT Position
  70. GRB 050315: potential host galaxy
  71. GRB050326: analysis of the XMM-Newton observation
  72. GRB050418: Null Optical Observations
  73. GRB050416A, optical observations
  74. GRB 050418: Swift-BAT refined analysis
  75. GRB 050416: Mitsume optical observation
  76. GRB 050416b: Swift-BAT refined analysis
  77. GRB050416B: IR observations
  78. GRB050412: Radio Observations
  79. GRB 050416: Swift/UVOT detection of afterglow emission
  80. GRB 050416: Swift-BAT refined analysis
  81. GRB 050416,optical observation
  82. GRB050416: P200 NIR Observations
  83. GRB 050416: Radio observations
  84. Swift BAT/XRT Detection of GRB 050416
  85. GRB 050412: Subaru observations
  86. GRB 050412: PROMPT VRcIc Observations
  87. GRB 050408: Kuiper 1.5m observations
  88. GRB 050412 : XingLong optical observation
  89. GRB 050412: Swift-BAT refined analysis
  90. GRB 050412: Early Optical/Ultraviolet Observations with
  91. GRB 050408: SDSS Field Calibration
  92. GRB 050412: Optical limit
  93. GRB050412: P60 Observations
  94. GRB050412: ROTSE-III Optical Limits
  95. Swift-BAT Detection of GRB 050412: A Bright, Long Burst
  96. GRB 050412: IR and Optical observations
  97. GRB 050412: IR Observations
  98. GRB050408: Radio Observations
  99. GRB 050401: Optical limit
  100. GRB 050408: Optical limit

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