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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"

19600 results found.

  1. GRB 050906: Swift-BAT refined analysis
  2. GRB 050906: Swift XRT upper limit
  3. GRB050906: P60 Observations
  4. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  5. GRB 050906: Bright galaxy in BAT error box
  6. GRB 050906: Swift/BAT Detection of a possible burst
  7. GRB 050904: Swift/UVOT observations
  8. GRB 050904: early Swift XRT analysis results
  9. GRB 050904: BAT refined analysis of partial data set
  10. GRB050904: P60 Observations
  11. GRB 050904: TAROT optical limits
  12. GRB050904: Swift-BAT detection of a probable burst
  13. Swift-BAT triggers 153461-153465 are not GRBs
  14. Retraction of Swift-BAT trigger #153355
  15. GRB 050824: MDM Observations
  16. GRB 050827: Swift XRT preliminary analysis results
  17. Swift Trigger #152652 is not a GRB
  18. GRB050827: Swift/UVOT upper limits
  19. GRB 050827: Optical Limit
  20. GRB 050827: XRT possible afterglow detection
  21. GRB050827: RTT150 optical observations
  22. GRB 050827: Swift-BAT refined analysis
  23. GRB050827: Swift-BAT detection of a burst
  24. GRB 050826: Optical Candidate
  25. GRB050824, HETE-2 Observation
  26. GRB 050826: Swift XRT preliminary analysis results
  27. GRB 050826: BAT refined analysis
  28. GRB050826: Swift/UVOT early upper limits
  29. GRB050824: First 2 hours of power low optical decay?
  30. GRB 050826: Swift XRT position
  31. GRB050826: Swift-BAT detection of a long burst
  32. GRB050824: MASTER final analysis of the OT observations
  33. Possible GRB050825:MASTER optical observations
  34. Swift-BAT trigger 152038 is definitely not a GRB
  35. GRB050824: CORRECTION to UVOT observing times
  36. Swift-BAT trigger 152038 is probably not a GRB
  37. GRB050824: Swift/UVOT detection of fading afterglow
  38. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  39. GRB050824, I-band imaging
  40. GRB 050822: refined XRT analysis
  41. GRB 050824: XRT refined analysis and possible afterglow detection
  42. GRB 050824: BAT refined analysis of a soft weak burst
  43. GRB050824: MASTER:OT decay
  44. GRB050824: MASTER observation OT
  45. GRB050805a: MASTER optical candidat
  46. GRB 050824: ROTSE-III Optical Limits
  47. GRB050824: Swift-BAT detection of a burst
  48. GRB050822: Swift/UVOT upper limits
  49. GRB 050820A BAT observations of second, larger episode of emission
  50. GRB 050822: Swift-BAT refined analysis
  51. GRB 050820a - corrections to GCN 3846
  52. Swift/UVOT UV Photometry of GRB 050820B
  53. GRB 050822: ROTSE-III Prompt Optical Limits
  54. GRB 050822: Swift detection of a long burst
  55. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  56. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  57. GRB050820a BVRcIc field photometry
  58. GRB050820B XMM-Newton observation
  59. GRB 050820a: NIR Observations by WIRO
  60. GRB 050820B: Swift XRT position
  61. GRB050820B: Refined analysis of the Swift-BAT burst
  62. GRB050820B: BAT-Swift detection of a bright GRB
  63. Swift/UVOT photometry of GRB050820
  64. GRB050820: refined XRT analysis
  65. GRB 050820: Early RAPTOR detections
  66. GRB 050820 Swift-BAT refined analysis
  67. GRB050819: refined XRT analysis
  68. GRB 050820: Swift detection of a GRB
  69. GRB050820: Optical afterglow from P60
  70. GRB 050819 Swift-BAT refined analysis
  71. GRB050819: Swift XRT position
  72. GRB050819: Swift-BAT detection of a weak burst
  73. Swift-BAT trigger 150993 is not a GRB
  74. Swift Trigger 150823 is HETE J1900.1-2455
  75. GRB050817: Swift-BAT Detection of a burst
  76. GRB050815: Optical afterglow detection by Swift UVOT
  77. GRB050815: XRT refined analysis
  78. GRB050815: Refined analysis of the Swift-BAT burst
  79. GRB 050815: ROTSE-III Optical Limits
  80. GRB050815: Swift XRT afterglow localization
  81. GRB050815: Swift-BAT detection of a burst
  82. GRB050814: P60 Optical Afterglow Candidate
  83. GRB 050814: XRT refined analysis
  84. GRB050814: SWIFT/UVOT observation
  85. GRB050814: Refined analysis of the Swift-BAT burst
  86. GRB 050814: Swift XRT Afterglow Localization
  87. GRB 050814: Swift detection of a burst
  88. GRB050813, SDSS pre-burst observations
  89. GRB 050813: KAIT optical limit
  90. GRB 050813: Swift-BAT refined analysis
  91. GRB050813: SWIFT/UVOT observation
  92. GRB 050813: Swift XRT afterglow localization
  93. GRB 050813: Possible Short Swift-BAT GRB
  94. GRB050813 (Swift 150139): P60 Observations
  95. Swift-BAT trigger 150131 is not a GRB
  96. GRB050805b: CrAO optical limit
  97. GRB050805a : Null detection report
  98. Swift-BAT trigger 149118 is very likely not a GRB
  99. Retraction of Swift Trigger 149131 (GRB 050805B)
  100. GRB 050805b: OHP optical limits

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