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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 : OSN 1.5m optical observations
  2. GRB 050827: P200 NIR Observations
  3. GRB050827: Swift/UVOT upper limits
  4. GRB 050827: Optical Limit
  5. GRB 050827: XRT possible afterglow detection
  6. GRB 050826 : Lulin R band observation
  7. GRB050824: Maidanak optical limits
  8. GRB050820A: RTT150 optical observations
  9. GRB050827: RTT150 optical observations
  10. GRB 050827: Swift-BAT refined analysis
  11. GRB050827: Swift-BAT detection of a burst
  12. Subaru Observations of GRB050724
  13. GRB 050826: Optical Candidate
  14. GRB050824, HETE-2 Observation
  15. GRB 050826: Swift XRT preliminary analysis results
  16. GRB 050826: BAT refined analysis
  17. GRB050826: Swift/UVOT early upper limits
  18. GRB050824: First 2 hours of power low optical decay?
  19. GRB 050826: Swift XRT position
  20. GRB050826: Swift-BAT detection of a long burst
  21. GRB050824: MASTER final analysis of the OT observations
  22. Possible GRB050825:MASTER optical observations
  23. Swift-BAT trigger 152038 is definitely not a GRB
  24. GRB050824: CORRECTION to UVOT observing times
  25. Swift-BAT trigger 152038 is probably not a GRB
  26. GRB050824: Swift/UVOT detection of fading afterglow
  27. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  28. GRB050824, I-band imaging
  29. GRB050824: Radio Observations
  30. GRB 050824: Spectroscopic redshift from the VLT
  31. GRB 050822: refined XRT analysis
  32. GRB 050824: XRT refined analysis and possible afterglow detection
  33. GRB 050824: BAT refined analysis of a soft weak burst
  34. GRB050824: MASTER:OT decay
  35. GRB050824: MASTER observation OT
  36. GRB050805a: MASTER optical candidat
  37. GRB 050824: ROTSE-III Optical Limits
  38. GRB050824: Swift-BAT detection of a burst
  39. GRB 050824 optical candidate
  40. GRB050820A: RTT150 optical observations
  41. GRB050820a: PROMPT RcIc Observations
  42. GRB050815: Maidanak optical observation
  43. XRF050509c: Radio upper limits from GMRT
  44. VLT/UVES spectroscopy of GRB050820
  45. GRB050822: Swift/UVOT upper limits
  46. GRB 050820A BAT observations of second, larger episode of emission
  47. GRB050813: Maidanak I-band observations
  48. GRB 050822: Swift-BAT refined analysis
  49. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  50. GRB050820B at FRAM
  51. GRB050820A: RTT150 optical observations
  52. GRB 050820a - corrections to GCN 3846
  53. Swift/UVOT UV Photometry of GRB 050820B
  54. GRB 050822: ROTSE-III Prompt Optical Limits
  55. GRB 050822: Swift detection of a long burst
  56. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  57. GRB050820A: Radio Observation
  58. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  59. GRB050820a BVRcIc field photometry
  60. GRB050820B XMM-Newton observation
  61. GRB 050820a: NIR Observations by WIRO
  62. GRB 050820B: Swift XRT position
  63. GRB050820B: Planned XMM-Newton observation
  64. SUBJECT: GRB050820B: Refined analysis of the Swift-BAT burst
  65. GRB050820B: BAT-Swift detection of a bright GRB
  66. Swift/UVOT photometry of GRB050820
  67. GRB050820: refined XRT analysis
  68. GRB 050820: Early RAPTOR detections
  69. GRB 050820 Swift-BAT refined analysis
  70. GRB 050820: P60 Temporal Decay Index
  71. GRB 050820: High Resolution Spectroscopy from Keck
  72. GRB050819: refined XRT analysis
  73. GRB050819: RTT150 optical observations
  74. GRB 050820: Swift detection of a GRB
  75. GRB050820: Optical afterglow from P60
  76. GRB 050819 Swift-BAT refined analysis
  77. GRB050819: Swift XRT position
  78. GRB050819: Swift-BAT detection of a weak burst
  79. Swift-BAT trigger 150993 is not a GRB
  80. Swift Trigger 150823 is HETE J1900.1-2455
  81. GRB 050817: Optical observations
  82. GRB 050815: Radio Observation
  83. GRB050814: Radio Observation
  84. GRB050817: Negative Optical Observations
  85. GRB050817: Swift-BAT Detection of a burst
  86. GRB 050814: continued fading
  87. GRB050815: Optical afterglow detection by Swift UVOT
  88. GRB050815: XRT refined analysis
  89. GRB 050813: Radio Observations
  90. GRB050815: Refined analysis of the Swift-BAT burst
  91. GRB 050815: ROTSE-III Optical Limits
  92. GRB050815: Swift XRT afterglow localization
  93. GRB050815: Swift-BAT detection of a burst
  94. GRB 050730: Third Epoch WSRT Radio Observations
  95. GRB050814: Fading red source
  96. GRB 050813: Gemini Spectra Revisited
  97. GRB050814: P60 Optical Afterglow Candidate
  98. GRB 050813: Non-fading of afterglow candidate
  99. GRB 050814: XRT refined analysis
  100. GRB050814: SWIFT/UVOT observation

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