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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 050827: P200 NIR Observations
  2. GRB050827: Swift/UVOT upper limits
  3. GRB 050827: Optical Limit
  4. GRB 050827: XRT possible afterglow detection
  5. GRB 050826 : Lulin R band observation
  6. GRB050824: Maidanak optical limits
  7. GRB050820A: RTT150 optical observations
  8. GRB050827: RTT150 optical observations
  9. GRB 050827: Swift-BAT refined analysis
  10. GRB050827: Swift-BAT detection of a burst
  11. Subaru Observations of GRB050724
  12. GRB 050826: Optical Candidate
  13. GRB050824, HETE-2 Observation
  14. GRB 050826: Swift XRT preliminary analysis results
  15. GRB 050826: BAT refined analysis
  16. GRB050826: Swift/UVOT early upper limits
  17. GRB050824: First 2 hours of power low optical decay?
  18. GRB 050826: Swift XRT position
  19. GRB050826: Swift-BAT detection of a long burst
  20. GRB050824: MASTER final analysis of the OT observations
  21. Possible GRB050825:MASTER optical observations
  22. Swift-BAT trigger 152038 is definitely not a GRB
  23. GRB050824: CORRECTION to UVOT observing times
  24. Swift-BAT trigger 152038 is probably not a GRB
  25. GRB050824: Swift/UVOT detection of fading afterglow
  26. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  27. GRB050824, I-band imaging
  28. GRB050824: Radio Observations
  29. GRB 050824: Spectroscopic redshift from the VLT
  30. GRB 050822: refined XRT analysis
  31. GRB 050824: XRT refined analysis and possible afterglow detection
  32. GRB 050824: BAT refined analysis of a soft weak burst
  33. GRB050824: MASTER:OT decay
  34. GRB050824: MASTER observation OT
  35. GRB050805a: MASTER optical candidat
  36. GRB 050824: ROTSE-III Optical Limits
  37. GRB050824: Swift-BAT detection of a burst
  38. GRB 050824 optical candidate
  39. GRB050820A: RTT150 optical observations
  40. GRB050820a: PROMPT RcIc Observations
  41. GRB050815: Maidanak optical observation
  42. XRF050509c: Radio upper limits from GMRT
  43. VLT/UVES spectroscopy of GRB050820
  44. GRB050822: Swift/UVOT upper limits
  45. GRB 050820A BAT observations of second, larger episode of emission
  46. GRB050813: Maidanak I-band observations
  47. GRB 050822: Swift-BAT refined analysis
  48. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  49. GRB050820B at FRAM
  50. GRB050820A: RTT150 optical observations
  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. GRB050820A: Radio Observation
  57. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  58. GRB050820a BVRcIc field photometry
  59. GRB050820B XMM-Newton observation
  60. GRB 050820a: NIR Observations by WIRO
  61. GRB 050820B: Swift XRT position
  62. GRB050820B: Planned XMM-Newton observation
  63. SUBJECT: GRB050820B: Refined analysis of the Swift-BAT burst
  64. GRB050820B: BAT-Swift detection of a bright GRB
  65. Swift/UVOT photometry of GRB050820
  66. GRB050820: refined XRT analysis
  67. GRB 050820: Early RAPTOR detections
  68. GRB 050820 Swift-BAT refined analysis
  69. GRB 050820: P60 Temporal Decay Index
  70. GRB 050820: High Resolution Spectroscopy from Keck
  71. GRB050819: refined XRT analysis
  72. GRB050819: RTT150 optical observations
  73. GRB 050820: Swift detection of a GRB
  74. GRB050820: Optical afterglow from P60
  75. GRB 050819 Swift-BAT refined analysis
  76. GRB050819: Swift XRT position
  77. GRB050819: Swift-BAT detection of a weak burst
  78. Swift-BAT trigger 150993 is not a GRB
  79. Swift Trigger 150823 is HETE J1900.1-2455
  80. GRB 050817: Optical observations
  81. GRB 050815: Radio Observation
  82. GRB050814: Radio Observation
  83. GRB050817: Negative Optical Observations
  84. GRB050817: Swift-BAT Detection of a burst
  85. GRB 050814: continued fading
  86. GRB050815: Optical afterglow detection by Swift UVOT
  87. GRB050815: XRT refined analysis
  88. GRB 050813: Radio Observations
  89. GRB050815: Refined analysis of the Swift-BAT burst
  90. GRB 050815: ROTSE-III Optical Limits
  91. GRB050815: Swift XRT afterglow localization
  92. GRB050815: Swift-BAT detection of a burst
  93. GRB 050730: Third Epoch WSRT Radio Observations
  94. GRB050814: Fading red source
  95. GRB 050813: Gemini Spectra Revisited
  96. GRB050814: P60 Optical Afterglow Candidate
  97. GRB 050813: Non-fading of afterglow candidate
  98. GRB 050814: XRT refined analysis
  99. GRB050814: SWIFT/UVOT observation
  100. GRB050814: Refined analysis of the Swift-BAT burst

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