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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"

26328 results found.

  1. GRB 050509A: Further I-band imaging
  2. GRB050522,optical observation
  3. GRB050520,optical observation
  4. XRF 050522: Continued NIR P200 Monitoring
  5. RBO Observations of GRB050522
  6. Recent GRB BVRcIc field photometry
  7. GRB050520: Radio Observations
  8. XRF 050522: Swift XRT observation
  9. XRF050522, BVRcIc field photometry
  10. XRF050522: Optical Observations
  11. XRF050522: Near-infrared Observations
  12. GRB 050520: VLT/ULTRACAM observations
  13. GRB 050520: Swift XRT refined analysis
  14. XRF050509C: Chandra Afterglow Detection
  15. XRF050509c: Radio Observations
  16. GRB 050520: P200 Observations
  17. GRB 050520: TAROT optical limit
  18. GRB 050520: VLT/ULTRACAM observations
  19. XRF 050509c optical afterglow
  20. GRB 050509B and short GRB-SN association? (corrected)
  21. GRB 050509B and short GRB-SN association?
  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 observations at the Very Large Telescope
  31. GRB 050509b: No Optical Variability in XRT Error Circle
  32. GRB 050509a: Swift-BAT refined analysis
  33. GRB 050509c: ROTSE-III Optical Limits
  34. GRB 050505, early TAROT observation
  35. GRB050509c: REM NIR and Optical observations
  36. GRB 050509b: Physical Properties of the Candidate Host galaxy
  37. GRB 050505: SARA Observations
  38. GRB 050509B, Optical Observations
  39. GRB 050509B: Swift/XRT refined analysis
  40. GRB 050509b: Optical observations
  41. GRB 050509A: Optical observations
  42. GRB050509b: Radio Observations
  43. GRB 050509b: PAIRITEL and WIYN Observations
  44. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  45. Swift Detection of GRB050509b: A short duration burst
  46. Swift Detection of the Burst GRB050509
  47. GRB 050505: early time observations
  48. GRB 050505, simultaneous optical observation
  49. GRB050505: AAVSO observations
  50. GRB050416A : 1 GHz limit from GMRT
  51. GRB050505: Optical Afterglow Candidate
  52. GRB050505 Swift-BAT refined analysis
  53. GRB 050416b:Swift XRT afterglow upper limits
  54. GRB 050416b:Swift XRT afterglow upper limits
  55. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  56. GRB050502b: Afterglow Confirmation
  57. GRB050502: P200 Observations (Correction)
  58. GRB050502: P200 Observations
  59. GRB 050504 : R band observation at Lulin observatory
  60. Swift UVOT observation of GRB 050504
  61. GRB 050504, R band Observations
  62. GRB 050502b, V band Observations
  63. GRB050504: P60 Observations
  64. GRB 050504: A long GRB detected with INTEGRAL
  65. GRB (?) 050504: IR Observations, Intriguing Source
  66. GRB 050502b, Optical observations
  67. GRB050502a: P60 Observations (Correction)
  68. GRB050502a: P60 Observations
  69. Renewal of SGR 1806-20 activity
  70. GRB050502B Swift-BAT refined analysis
  71. Swift UVOT refined analysis
  72. GRB 050502a : R band observation at Lulin observatory
  73. GRB 050502b : optical observation at Lulin observatory
  74. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  75. Swift Detection of the Bright Burst GRB050502b
  76. GRB 050502: INTEGRAL results
  77. GRB 050502: ROTSE-III Detection of Possible Counterpart
  78. Swift/BAT possible detection of a weak burst GRB050430
  79. GRB050416a: Radio Detection
  80. GRB 050422: Swift-UVOT observation
  81. GRB 050422: Swift-BAT refined analysis
  82. Swift Detection of GRB 050422
  83. GRB 050421: SLOTIS observations
  84. GRB 050421: Further Analysis of IR imaging
  85. GRB050421: Radio Observations
  86. GRB050421: Radio Observations
  87. GRB 050421: IR Observations
  88. GRB 050421: Swift-BAT refined analysis
  89. GRB050421
  90. GRB 050421: early Swift XRT analysis results
  91. GRB 050421: NIR observations
  92. GRB050421: P60 Observations
  93. GRB 050421: BOOTES-2 simultaneous optical observations
  94. GRB 050416b: Tentative Swift XRT Position
  95. GRB 050315: potential host galaxy
  96. GRB050326: analysis of the XMM-Newton observation
  97. GRB050418: Null Optical Observations
  98. GRB050416A, optical observations
  99. GRB 050418: Swift-BAT refined analysis
  100. GRB 050416: Mitsume optical observation

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