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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"

28100 results found.

  1. GRB 060923: Swift detection of a burst
  2. Swift detection of IGR J17497-2821 (trigger 230504)
  3. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  4. GRB060919: Swift/UVOT optical observations
  5. GRB 060919 : Faulkes South Telescope Observations
  6. GRB060919: XRT refined analysis
  7. GRB 060919: Swift detection of a burst
  8. GRB 060912A: VLA Observation
  9. GRB 060912A: Probable Host Galaxy
  10. GRB060825: MAGIC telescope GeV observation
  11. GRB 060912: Redshift of nearby 2MASS galaxy
  12. GRB060912: optical observations
  13. GRB060912: OPTIMA-Burst optical observations
  14. GRB 060912: Swift XRT Team Refined Analysis
  15. GRB 060912: Swift detection of a burst with an optical afterglow
  16. GRB060906: Danish/DFOSC optical observations
  17. VLA observations of GRB 060908
  18. GRB 060908, Swift/XRT refined analysis
  19. GRB 060908: Swift/UVOT Observations
  20. GRB 060904B : CFHT/WIRCam NIR afterglow observations
  21. GRB 060904B: Kiso Optical observation
  22. GRB 060904A : Optical limit
  23. GRB 060908: PROMPT Detection of a Bright Counterpart
  24. GRB 060908: Swift detection of a burst with a bright optical counterpart
  25. GRB 060906: optical observation
  26. GRB 060906: Early RAPTOR optical limits
  27. GRB 060906: Swift/XRT Refined Analysis
  28. GRB 060906: Swift-UVOT observations
  29. VLT redshift of GRB 060906
  30. GRB 060906: FRAM observations - flash determination (airplane)
  31. GRB 060906: KAIT observations
  32. GRB 060906: Confirmation of P60 Optical Afterglow
  33. GRB 060906: observations with FRAM
  34. GRB 060906 (?): P60 Optical Afterglow Candidate
  35. GRB 060906: Swift detection of a probable burst
  36. GRB 060904b: SMARTS optical/IR afterglow observations
  37. GRB060904A: Swift/UVOT optical observations
  38. GRB 060904A: Subaru NIR observation
  39. GRB060904b: Optical observations with Swift/UVOT
  40. GRB 060904B: Swift-XRT refined analysis
  41. GRB 060904A: Swift-XRT refined analysis
  42. GRB 060904A: P60 Observations
  43. GRB060904B: Watcher observations
  44. GRB 060904: TAROT optical observations
  45. GRB 060904B: Swift detection of a burst with optical counterpart
  46. GRB 060904B: ROTSE-III Detection of Optical Counterpart
  47. GRB 060904: Swift detection of a bright burst
  48. GRB060901: Optical observations
  49. 060901: Swift UVOT followup observations
  50. GRB 060901: SMARTS optical/IR observations update
  51. GRB 060901: Swift/XRT Refined Analysis
  52. GRB 060901: SMARTS optical/IR observations
  53. GRB 060901: Swift/XRT Position
  54. GRB 060901: Watcher observations
  55. GRB 060604: VLA Observation
  56. GRB 060605: VLA Observation
  57. GRB 060707: VLA observation
  58. GRB 060825: VLA observations
  59. GRB 060826(?): Swift detection of a possible burst
  60. GRB 060825: XRT Team Refined Analysis
  61. GRB 060825: TNG optical observations
  62. GRB 060825: P60 Observations
  63. GRB060825: BOOTES-IR optical observations
  64. GRB 060825: Swift detection of a burst
  65. GRB060729: analysis of XMM-Newton observation
  66. Radio observations of GRB 060719
  67. GRB 060729, SMARTS optical/IR observations
  68. GRB060814: Break in the XRT light curve
  69. GRB060813: Break in the XRT light curve
  70. GRB 060814: Confirmation of IR afterglow
  71. GRB 060814: P60 Observations
  72. GRB 060814: P200 NIR Observations
  73. GRB 060814: source inside revised XRT error box
  74. GRB 060814: Possible IR counterpart
  75. GRB060805B: optical observations
  76. GRB060814: Swift/UVOT upper limits
  77. GRB 060814: Swift XRT refined analysis
  78. GRB 060814: VLT optical limits
  79. GRB 060814: Swift detection of a bright burst
  80. GRB060813: Swift/UVOT upper limits
  81. GRB 060813: Swift XRT refined analysis
  82. GRB 060813: Swift detection of a burst
  83. GRB051109B: Late-time Radio Observations
  84. Image of the dust-scattering halo around SGR 1806-20
  85. Second VLA limit on new radio point source in SGR 1806-20
  86. A dust-scattering halo detected around SGR 1806-20
  87. Swift detection of an outburst from the 4U 1246-58 LMXB burster
  88. GRB060807: Possible Highly Significant X-ray Emission Lines
  89. GRB060714: optical observations
  90. GRB 060729: An update on the Swift XRT and UVOT observations
  91. GRB060717: optical observations
  92. GRB 060805B: optical observation at Sierra Nevada
  93. GRB 060805B: XRT Team Analysis
  94. VLA Upper Limit on Outburst of SGR 1806-20
  95. GRB 060807: UVOT Upper limits
  96. GRB 060807: afterglow confirmation
  97. GRB 060807: XRT Team refined analysis
  98. GRB060807: optical afterglow candidate
  99. GRB060807: optical upper limit in white light
  100. GRB 060805B: X-ray Afterglow Detection, Spectral/Spatial/Temporal Properties

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