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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: Swift XRT preliminary analysis results
  2. IBAS Alerts 2641 and 2642: not a real GRB
  3. Swift Trigger #152652 is not a GRB
  4. GRB 050827 : OSN 1.5m optical observations
  5. GRB 050827: P200 NIR Observations
  6. GRB050827: Swift/UVOT upper limits
  7. GRB 050827: Optical Limit
  8. GRB 050827: XRT possible afterglow detection
  9. GRB 050826 : Lulin R band observation
  10. GRB050824: Maidanak optical limits
  11. GRB050820A: RTT150 optical observations
  12. GRB050827: RTT150 optical observations
  13. GRB 050827: Swift-BAT refined analysis
  14. GRB050827: Swift-BAT detection of a burst
  15. Subaru Observations of GRB050724
  16. GRB 050826: Optical Candidate
  17. GRB050824, HETE-2 Observation
  18. GRB 050826: Swift XRT preliminary analysis results
  19. GRB 050826: BAT refined analysis
  20. GRB050826: Swift/UVOT early upper limits
  21. GRB050824: First 2 hours of power low optical decay?
  22. GRB 050826: Swift XRT position
  23. GRB050826: Swift-BAT detection of a long burst
  24. GRB050824: MASTER final analysis of the OT observations
  25. Possible GRB050825:MASTER optical observations
  26. Swift-BAT trigger 152038 is definitely not a GRB
  27. GRB050824: CORRECTION to UVOT observing times
  28. Swift-BAT trigger 152038 is probably not a GRB
  29. GRB050824: Swift/UVOT detection of fading afterglow
  30. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  31. GRB050824, I-band imaging
  32. GRB050824: Radio Observations
  33. GRB 050824: Spectroscopic redshift from the VLT
  34. GRB 050822: refined XRT analysis
  35. GRB 050824: XRT refined analysis and possible afterglow detection
  36. GRB 050824: BAT refined analysis of a soft weak burst
  37. GRB050824: MASTER:OT decay
  38. GRB050824: MASTER observation OT
  39. GRB050805a: MASTER optical candidat
  40. GRB 050824: ROTSE-III Optical Limits
  41. GRB050824: Swift-BAT detection of a burst
  42. GRB 050824 optical candidate
  43. GRB050820A: RTT150 optical observations
  44. GRB050820a: PROMPT RcIc Observations
  45. GRB050815: Maidanak optical observation
  46. XRF050509c: Radio upper limits from GMRT
  47. VLT/UVES spectroscopy of GRB050820
  48. GRB050822: Swift/UVOT upper limits
  49. GRB 050820A BAT observations of second, larger episode of emission
  50. GRB050813: Maidanak I-band observations
  51. GRB 050822: Swift-BAT refined analysis
  52. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  53. GRB050820B at FRAM
  54. GRB050820A: RTT150 optical observations
  55. GRB 050820a - corrections to GCN 3846
  56. Swift/UVOT UV Photometry of GRB 050820B
  57. GRB 050822: ROTSE-III Prompt Optical Limits
  58. GRB 050822: Swift detection of a long burst
  59. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  60. GRB050820A: Radio Observation
  61. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  62. GRB050820a BVRcIc field photometry
  63. GRB050820B XMM-Newton observation
  64. GRB 050820a: NIR Observations by WIRO
  65. GRB 050820B: Swift XRT position
  66. GRB050820B: Planned XMM-Newton observation
  67. GRB050820B: Refined analysis of the Swift-BAT burst
  68. GRB050820B: BAT-Swift detection of a bright GRB
  69. Swift/UVOT photometry of GRB050820
  70. GRB050820: refined XRT analysis
  71. GRB 050820: Early RAPTOR detections
  72. GRB 050820 Swift-BAT refined analysis
  73. GRB 050820: P60 Temporal Decay Index
  74. GRB 050820: High Resolution Spectroscopy from Keck
  75. GRB050819: refined XRT analysis
  76. GRB050819: RTT150 optical observations
  77. GRB 050820: Swift detection of a GRB
  78. GRB050820: Optical afterglow from P60
  79. GRB 050819 Swift-BAT refined analysis
  80. GRB050819: Swift XRT position
  81. GRB050819: Swift-BAT detection of a weak burst
  82. Swift-BAT trigger 150993 is not a GRB
  83. Swift Trigger 150823 is HETE J1900.1-2455
  84. GRB 050817: Optical observations
  85. GRB 050815: Radio Observation
  86. GRB050814: Radio Observation
  87. GRB050817: Negative Optical Observations
  88. GRB050817: Swift-BAT Detection of a burst
  89. GRB 050814: continued fading
  90. GRB050815: Optical afterglow detection by Swift UVOT
  91. GRB050815: XRT refined analysis
  92. GRB 050813: Radio Observations
  93. GRB050815: Refined analysis of the Swift-BAT burst
  94. GRB 050815: ROTSE-III Optical Limits
  95. GRB050815: Swift XRT afterglow localization
  96. GRB050815: Swift-BAT detection of a burst
  97. GRB 050730: Third Epoch WSRT Radio Observations
  98. GRB050814: Fading red source
  99. GRB 050813: Gemini Spectra Revisited
  100. GRB050814: P60 Optical Afterglow Candidate

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