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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"

18568 results found.

  1. GRB050826: Swift-BAT detection of a long burst
  2. GRB050824: MASTER final analysis of the OT observations
  3. Possible GRB050825:MASTER optical observations
  4. Swift-BAT trigger 152038 is definitely not a GRB
  5. GRB050824: CORRECTION to UVOT observing times
  6. Swift-BAT trigger 152038 is probably not a GRB
  7. GRB050824: Swift/UVOT detection of fading afterglow
  8. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  9. GRB050824, I-band imaging
  10. GRB 050822: refined XRT analysis
  11. GRB 050824: XRT refined analysis and possible afterglow detection
  12. GRB 050824: BAT refined analysis of a soft weak burst
  13. GRB050824: MASTER:OT decay
  14. GRB050824: MASTER observation OT
  15. GRB050805a: MASTER optical candidat
  16. GRB 050824: ROTSE-III Optical Limits
  17. GRB050824: Swift-BAT detection of a burst
  18. GRB050822: Swift/UVOT upper limits
  19. GRB 050820A BAT observations of second, larger episode of emission
  20. GRB 050822: Swift-BAT refined analysis
  21. GRB 050820a - corrections to GCN 3846
  22. Swift/UVOT UV Photometry of GRB 050820B
  23. GRB 050822: ROTSE-III Prompt Optical Limits
  24. GRB 050822: Swift detection of a long burst
  25. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  26. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  27. GRB050820a BVRcIc field photometry
  28. GRB050820B XMM-Newton observation
  29. GRB 050820a: NIR Observations by WIRO
  30. GRB 050820B: Swift XRT position
  31. GRB050820B: Refined analysis of the Swift-BAT burst
  32. GRB050820B: BAT-Swift detection of a bright GRB
  33. Swift/UVOT photometry of GRB050820
  34. GRB050820: refined XRT analysis
  35. GRB 050820: Early RAPTOR detections
  36. GRB 050820 Swift-BAT refined analysis
  37. GRB050819: refined XRT analysis
  38. GRB 050820: Swift detection of a GRB
  39. GRB050820: Optical afterglow from P60
  40. GRB 050819 Swift-BAT refined analysis
  41. GRB050819: Swift XRT position
  42. GRB050819: Swift-BAT detection of a weak burst
  43. Swift-BAT trigger 150993 is not a GRB
  44. Swift Trigger 150823 is HETE J1900.1-2455
  45. GRB050817: Swift-BAT Detection of a burst
  46. GRB050815: Optical afterglow detection by Swift UVOT
  47. GRB050815: XRT refined analysis
  48. GRB050815: Refined analysis of the Swift-BAT burst
  49. GRB 050815: ROTSE-III Optical Limits
  50. GRB050815: Swift XRT afterglow localization
  51. GRB050815: Swift-BAT detection of a burst
  52. GRB050814: P60 Optical Afterglow Candidate
  53. GRB 050814: XRT refined analysis
  54. GRB050814: SWIFT/UVOT observation
  55. GRB050814: Refined analysis of the Swift-BAT burst
  56. GRB 050814: Swift XRT Afterglow Localization
  57. GRB 050814: Swift detection of a burst
  58. GRB050813, SDSS pre-burst observations
  59. GRB 050813: KAIT optical limit
  60. GRB 050813: Swift-BAT refined analysis
  61. GRB050813: SWIFT/UVOT observation
  62. GRB 050813: Swift XRT afterglow localization
  63. GRB 050813: Possible Short Swift-BAT GRB
  64. GRB050813 (Swift 150139): P60 Observations
  65. Swift-BAT trigger 150131 is not a GRB
  66. GRB050805b: CrAO optical limit
  67. GRB050805a : Null detection report
  68. Swift-BAT trigger 149118 is very likely not a GRB
  69. Retraction of Swift Trigger 149131 (GRB 050805B)
  70. GRB 050805b: OHP optical limits
  71. GRB 050805b: TAROT optical limits
  72. GRB050805b: MASTER optical observations
  73. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  74. GRB050805a: MASTER optical candidat
  75. Swift-BAT trigger 149118 is probably not a GRB
  76. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  77. GRB 050803: Swift-BAT refined analysis
  78. GRB050803: MASTER further analys
  79. GRB 050803: early Swift XRT analysis results
  80. GRB 050803: TAROT optical limits
  81. GRB050803: MASTER optical observations
  82. GRB050803: Swift-BAT detection of a very long burst
  83. GCN GRB observation 050713A
  84. GRB 050802: Swift/UVOT optical and UV detections
  85. GRB050802 radio non-detection
  86. GRB 050730: OHP optical observations
  87. GRB 050802: early Swift XRT analysis results
  88. GRB 050802: Swift/UVOT observations
  89. GRB 050802: Swift-BAT refined analysis
  90. GRB 050802: XRT position
  91. GRB 050802: Swift Gamma-ray Burst
  92. GRB050801: Swift/UVOT Optical and UV detections
  93. GCN 050801: early Swift XRT analysis results
  94. GRB 050801: Swift-BAT refined analysis
  95. GRB 050801, afterglow observations
  96. GRB 050730, corrected photometry and break?
  97. GRB 050801: ROTSE-III Early Afterglow Break
  98. GRB050801: Swift-BAT detection of a burst
  99. GRB050801: GCN XRT position is incorrect
  100. GRB 050801: ROTSE-III Detection of Possible Counterpart

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