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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"

35982 results found.

  1. GRB 050908: Swift detection of a burst
  2. Swift trigger 154073 is not a GRB
  3. GRB 050906: Optical observations at the Very Large Telescope
  4. GRB050904: CrAO optical observations
  5. GRB 050904 BAT refined analysis of complete data set
  6. GRB 050904: Subaru Optical Spectroscopy
  7. GRB 050906: MARGE Optical Limits
  8. GRB 050906: Swift-BAT refined analysis
  9. GRB 050906: Swift XRT upper limit
  10. GRB 050906: Radio Observations
  11. GRB 050904: Keck I-band Imaging
  12. GRB 050904: more VLT NIR observations
  13. GRB 050904: BOOTES early R-band observation
  14. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  15. GRB 050906: Bright galaxy in BAT error box
  16. GRB 050906: Swift/BAT Detection of a possible burst
  17. GRB 050904: More SOAR
  18. GRB 050904: photometric redshift
  19. GRB 050904: Swift/UVOT observations
  20. GRB 050904: Afterglow Astrometry
  21. GRB 050904: NIR object inside the XRT error box
  22. GRB 050904: early Swift XRT analysis results
  23. GRB 050904: SOAR YJ and PROMPT Ic Observations
  24. GRB 050904: BAT refined analysis of partial data set
  25. GRB 050904: TAROT optical measurements
  26. GRB050904: Optical Observations
  27. GRB 050904: Environmental Constraints
  28. GRB 050904: Possible High-Redshift GRB
  29. GRB 050904: SOAR/PROMPT Observations
  30. GRB 050904: TAROT optical limits
  31. Swift-BAT triggers 153461-153465 are not GRBs
  32. GRB 050824: MDM Observations
  33. GRB 050827: Swift XRT preliminary analysis results
  34. IBAS Alerts 2641 and 2642: not a real GRB
  35. Swift Trigger #152652 is not a GRB
  36. GRB 050827 : OSN 1.5m optical observations
  37. GRB 050827: P200 NIR Observations
  38. GRB 050827: Optical Limit
  39. GRB 050827: XRT possible afterglow detection
  40. GRB 050826 : Lulin R band observation
  41. GRB050824: Maidanak optical limits
  42. GRB050820A: RTT150 optical observations
  43. GRB050827: RTT150 optical observations
  44. GRB 050827: Swift-BAT refined analysis
  45. GRB 050826: Optical Candidate
  46. GRB050824, HETE-2 Observation
  47. GRB 050826: Swift XRT preliminary analysis results
  48. GRB 050826: BAT refined analysis
  49. GRB050824: First 2 hours of power low optical decay?
  50. GRB 050826: Swift XRT position
  51. GRB050826: Swift-BAT detection of a long burst
  52. GRB050824: MASTER final analysis of the OT observations
  53. Possible GRB050825:MASTER optical observations
  54. Swift-BAT trigger 152038 is definitely not a GRB
  55. Swift-BAT trigger 152038 is probably not a GRB
  56. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  57. GRB050824, I-band imaging
  58. GRB050824: Radio Observations
  59. GRB 050824: Spectroscopic redshift from the VLT
  60. GRB 050822: refined XRT analysis
  61. GRB 050824: XRT refined analysis and possible afterglow detection
  62. GRB 050824: BAT refined analysis of a soft weak burst
  63. GRB050824: MASTER:OT decay
  64. GRB050824: MASTER observation OT
  65. GRB050805a: MASTER optical candidat
  66. GRB 050824: ROTSE-III Optical Limits
  67. GRB050824: Swift-BAT detection of a burst
  68. GRB 050824 optical candidate
  69. GRB050820A: RTT150 optical observations
  70. GRB050820a: PROMPT RcIc Observations
  71. GRB050815: Maidanak optical observation
  72. XRF050509c: Radio upper limits from GMRT
  73. VLT/UVES spectroscopy of GRB050820
  74. GRB 050820A BAT observations of second, larger episode of emission
  75. GRB050813: Maidanak I-band observations
  76. GRB 050822: Swift-BAT refined analysis
  77. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  78. GRB050820B at FRAM
  79. GRB050820A: RTT150 optical observations
  80. GRB 050820a - corrections to GCN 3846
  81. Swift/UVOT UV Photometry of GRB 050820B
  82. GRB 050822: ROTSE-III Prompt Optical Limits
  83. GRB 050822: Swift detection of a long burst
  84. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  85. GRB050820A: Radio Observation
  86. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  87. GRB050820a BVRcIc field photometry
  88. GRB 050820a: NIR Observations by WIRO
  89. GRB 050820B: Swift XRT position
  90. GRB050820B: Refined analysis of the Swift-BAT burst
  91. GRB050820B: BAT-Swift detection of a bright GRB
  92. GRB050820: refined XRT analysis
  93. GRB 050820: Early RAPTOR detections
  94. GRB 050820 Swift-BAT refined analysis
  95. GRB 050820: P60 Temporal Decay Index
  96. GRB 050820: High Resolution Spectroscopy from Keck
  97. GRB050819: RTT150 optical observations
  98. GRB 050820: Swift detection of a GRB
  99. GRB 050819 Swift-BAT refined analysis
  100. GRB050819: Swift XRT position

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