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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"
  1. GRB 050904: SOAR/PROMPT Observations
  2. GRB050904: P60 Observations
  3. GRB 050904: TAROT optical limits
  4. GRB050904: Swift-BAT detection of a probable burst
  5. Swift-BAT triggers 153461-153465 are not GRBs
  6. Retraction of Swift-BAT trigger #153355
  7. GRB 050824: MDM Observations
  8. GRB 050827: Swift XRT preliminary analysis results
  9. IBAS Alerts 2641 and 2642: not a real GRB
  10. Swift Trigger #152652 is not a GRB
  11. GRB 050827 : OSN 1.5m optical observations
  12. GRB 050827: P200 NIR Observations
  13. GRB050827: Swift/UVOT upper limits
  14. GRB 050827: Optical Limit
  15. GRB 050827: XRT possible afterglow detection
  16. GRB 050826 : Lulin R band observation
  17. GRB050824: Maidanak optical limits
  18. GRB050820A: RTT150 optical observations
  19. GRB050827: RTT150 optical observations
  20. GRB 050827: Swift-BAT refined analysis
  21. GRB050827: Swift-BAT detection of a burst
  22. Subaru Observations of GRB050724
  23. GRB 050826: Optical Candidate
  24. GRB050824, HETE-2 Observation
  25. GRB 050826: Swift XRT preliminary analysis results
  26. GRB 050826: BAT refined analysis
  27. GRB050826: Swift/UVOT early upper limits
  28. GRB050824: First 2 hours of power low optical decay?
  29. GRB 050826: Swift XRT position
  30. GRB050826: Swift-BAT detection of a long burst
  31. GRB050824: MASTER final analysis of the OT observations
  32. Possible GRB050825:MASTER optical observations
  33. Swift-BAT trigger 152038 is definitely not a GRB
  34. GRB050824: CORRECTION to UVOT observing times
  35. Swift-BAT trigger 152038 is probably not a GRB
  36. GRB050824: Swift/UVOT detection of fading afterglow
  37. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  38. GRB050824, I-band imaging
  39. GRB050824: Radio Observations
  40. GRB 050824: Spectroscopic redshift from the VLT
  41. GRB 050822: refined XRT analysis
  42. GRB 050824: XRT refined analysis and possible afterglow detection
  43. GRB 050824: BAT refined analysis of a soft weak burst
  44. GRB050824: MASTER:OT decay
  45. GRB050824: MASTER observation OT
  46. GRB050805a: MASTER optical candidat
  47. GRB 050824: ROTSE-III Optical Limits
  48. GRB050824: Swift-BAT detection of a burst
  49. GRB 050824 optical candidate
  50. GRB050820A: RTT150 optical observations
  51. GRB050820a: PROMPT RcIc Observations
  52. GRB050815: Maidanak optical observation
  53. XRF050509c: Radio upper limits from GMRT
  54. VLT/UVES spectroscopy of GRB050820
  55. GRB050822: Swift/UVOT upper limits
  56. GRB 050820A BAT observations of second, larger episode of emission
  57. GRB050813: Maidanak I-band observations
  58. GRB 050822: Swift-BAT refined analysis
  59. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  60. GRB050820B at FRAM
  61. GRB050820A: RTT150 optical observations
  62. GRB 050820a - corrections to GCN 3846
  63. Swift/UVOT UV Photometry of GRB 050820B
  64. GRB 050822: ROTSE-III Prompt Optical Limits
  65. GRB 050822: Swift detection of a long burst
  66. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  67. GRB050820A: Radio Observation
  68. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  69. GRB050820a BVRcIc field photometry
  70. GRB050820B XMM-Newton observation
  71. GRB 050820a: NIR Observations by WIRO
  72. GRB 050820B: Swift XRT position
  73. GRB050820B: Planned XMM-Newton observation
  74. GRB050820B: Refined analysis of the Swift-BAT burst
  75. GRB050820B: BAT-Swift detection of a bright GRB
  76. Swift/UVOT photometry of GRB050820
  77. GRB050820: refined XRT analysis
  78. GRB 050820: Early RAPTOR detections
  79. GRB 050820 Swift-BAT refined analysis
  80. GRB 050820: P60 Temporal Decay Index
  81. GRB 050820: High Resolution Spectroscopy from Keck
  82. GRB050819: refined XRT analysis
  83. GRB050819: RTT150 optical observations
  84. GRB 050820: Swift detection of a GRB
  85. GRB050820: Optical afterglow from P60
  86. GRB 050819 Swift-BAT refined analysis
  87. GRB050819: Swift XRT position
  88. GRB050819: Swift-BAT detection of a weak burst
  89. Swift-BAT trigger 150993 is not a GRB
  90. Swift Trigger 150823 is HETE J1900.1-2455
  91. GRB 050817: Optical observations
  92. GRB 050815: Radio Observation
  93. GRB050814: Radio Observation
  94. GRB050817: Negative Optical Observations
  95. GRB050817: Swift-BAT Detection of a burst
  96. GRB 050814: continued fading
  97. GRB050815: Optical afterglow detection by Swift UVOT
  98. GRB050815: XRT refined analysis
  99. GRB 050813: Radio Observations
  100. GRB050815: Refined analysis of the Swift-BAT burst

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