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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"

15710 results found.

  1. GRB 061121: MDM Continued Monitoring
  2. GRB 061122: Confirmation of X-ray/Optical Afterglow
  3. GRB 061121: MDM Continuing Optical Decay
  4. GRB061121: optical observations
  5. GRB 061122: Candidate Optical Afterglow
  6. GRB 061121: MDM Optical Decay
  7. GRB061122: Swift/UVOT Optical Observations
  8. GRB 061121: ART detection in Ic
  9. GRB 061121: MDM Optical Observations
  10. GRB 061121 declared "Burst of Interest" by Swift team
  11. GRB 061121: Swift/UVOT Observations
  12. GRB061121, optical observation
  13. GRB 061121: Optical observation at the KANATA 1.5m telescope
  14. GRB 061121: Faulkes Telescope North Optical Observation
  15. GRB061121: Spectroscopic Redshift
  16. GRB061121: Keck spectroscopic observations
  17. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  18. GRB 061121: Swift detection of a bright burst with an optical counterpart
  19. GRB 060605: NIR Observations
  20. GRB 050915B: optical afterglow
  21. GRB 061110B: Swift XRT refined analysis
  22. GRB061110B: Optical observations at Crni Vrh
  23. GRB 061110B: NOT optical observations
  24. GRB 061110A: Swift XRT refined analysis
  25. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  26. GRB 061110B: TAROT Calern observatory optical observations
  27. GRB 061110: NOT observations
  28. GRB 061110 : Optical afterglow candidate
  29. GRB 061110: ROTSE-III Optical Limits
  30. GRB061110A - Optical Non-detection
  31. GRB 061109: optical observation
  32. GRB 061109: TAROT Calern observatory optical observations
  33. GRB061028: MAGIC telescope GeV observation
  34. GRB 061027: TAROT La Silla observatory optical observations
  35. GRB 061007: Third Epoch ATCA Radio Observations
  36. GRB061019: second epoch CrAO observations
  37. GRB 061028: Swift/XRT Astrometry Correction
  38. GRB 061102: Swift/UVOT Magnitude Upper Limits
  39. GRB 061004: Further VLT/NTT observations
  40. GRB 061028: Optical R passband observations
  41. GRB 061004: Swift/XRT Astrometry Correction
  42. GRB 060801: Swift/XRT Astrometry Correction
  43. GRB 061028: SARA upper limit
  44. GRB 061028: TAROT Calern observatory late optical observations
  45. GRB 061028: TAROT Calern observatory optical observations
  46. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  47. GRB 061025: REM observations
  48. GRB 061025: ROTSE-III Optical Limits
  49. GRB 061021: Swift/UVOT Observation
  50. GRB060904b: optical observations
  51. GRB061019: optical observations
  52. GRB061019: optical observations
  53. GRB 061019: dust-scattered X-ray halo detected in Swift/XRT
  54. GRB 060930: MARGE Optical Limits
  55. GRB 061019: Swift/UVOT upper limit
  56. GRB 061019: SMARTS afterglow confirmation
  57. GRB 061019: TAROT La Silla observatory optical observations
  58. GRB 061019: REM K-band candidate afterglow
  59. GRB 060825: GORT Observations
  60. GRB 061007: Second Epoch ATCA Radio Observations
  61. GRB 061006: astrometry-corrected XRT position
  62. GRB 061007: ATCA Radio Observations
  63. GRB 061006: optical afterglow
  64. GRB 061007: OA fading and VLT redshift
  65. GRB 061006: Swift/UVOT optical observations
  66. GRB 061007 - FTS early brightening and power law decay
  67. GRB 061007: Swift detection of a burst with an optical counterpart
  68. GRB 061007: ROTSE-III Detection of Optical Counterpart
  69. GRB 061004: Optical afterglow candidate and redshift
  70. GRB 061004: Las Campanas Optical/NIR Observations
  71. GRB061004: Swift/UVOT optical observations
  72. GRB 060930: Xinglong TNT optical observations
  73. GRB 060929: Swift/UVOT Optical Observations
  74. GRB 060930: ROTSE-III Optical Limits
  75. GRB 060927 : GAO 150cm telescope optical observation
  76. GRB060929: Optical limit
  77. GRB 060929: BOOTES-IR & OSN observations
  78. GRB060908: optical observations
  79. GRB 060729: An update on the late-time Swift observations
  80. GRB060923C: optical limit
  81. GRB060927: optical observations
  82. GRB 060926: Swift-UVOT UVW1 Detection Retraction
  83. GRB 060927: Swift/UVOT Optical Observations
  84. GRB 060927: Early color
  85. GRB 060927: Swift XRT Team refined analysis
  86. GRB 060927 optical limit
  87. GRB 060927: Xinglong TNT optical observations
  88. GRB 060927, optical observation
  89. GRB 060927 : Kiso optical observation
  90. GRB 060927: optical afterglow confirmation
  91. GRB 060927A: ROTSE-III Detection of Optical Counterpart
  92. Swift XRT boresight
  93. GRB060926: VLT redshift
  94. GRB 060926: Swift-UVOT Detections
  95. GRB 060926: MASTER OT alert observation
  96. GRB 060926: BOOTES-IR observations
  97. GRB060926 OPTIMA-Burst optical observation
  98. GRB 060926: MASTER optical observation
  99. GRB060923C: AROMA optical obsevation
  100. GRB 060923C, optical observation

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