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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').
  1. GRB050906: P60 Observations
  2. GRB 050904: more VLT NIR observations
  3. GRB 050904: BOOTES early R-band observation
  4. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  5. GRB 050906: Bright galaxy in BAT error box
  6. GRB 050906: Swift/BAT Detection of a possible burst
  7. GRB 050904: More SOAR
  8. GRB 050904: photometric redshift
  9. GRB 050904: Swift/UVOT observations
  10. GRB 050904: Afterglow Astrometry
  11. GRB 050904: NIR object inside the XRT error box
  12. GRB 050904: early Swift XRT analysis results
  13. GRB 050904: SOAR YJ and PROMPT Ic Observations
  14. GRB 050904: BAT refined analysis of partial data set
  15. GRB 050904: TAROT optical measurements
  16. GRB050904: Optical Observations
  17. GRB 050904: Environmental Constraints
  18. GRB 050904: Possible High-Redshift GRB
  19. GRB 050904: SOAR/PROMPT Observations
  20. GRB050904: P60 Observations
  21. GRB 050904: TAROT optical limits
  22. GRB050904: Swift-BAT detection of a probable burst
  23. Swift-BAT triggers 153461-153465 are not GRBs
  24. Retraction of Swift-BAT trigger #153355
  25. GRB 050824: MDM Observations
  26. GRB 050827: Swift XRT preliminary analysis results
  27. IBAS Alerts 2641 and 2642: not a real GRB
  28. Swift Trigger #152652 is not a GRB
  29. GRB 050827 : OSN 1.5m optical observations
  30. GRB 050827: P200 NIR Observations
  31. GRB050827: Swift/UVOT upper limits
  32. GRB 050827: Optical Limit
  33. GRB 050827: XRT possible afterglow detection
  34. GRB 050826 : Lulin R band observation
  35. GRB050824: Maidanak optical limits
  36. GRB050820A: RTT150 optical observations
  37. GRB050827: RTT150 optical observations
  38. GRB 050827: Swift-BAT refined analysis
  39. GRB050827: Swift-BAT detection of a burst
  40. Subaru Observations of GRB050724
  41. GRB 050826: Optical Candidate
  42. GRB050824, HETE-2 Observation
  43. GRB 050826: Swift XRT preliminary analysis results
  44. GRB 050826: BAT refined analysis
  45. GRB050826: Swift/UVOT early upper limits
  46. GRB050824: First 2 hours of power low optical decay?
  47. GRB 050826: Swift XRT position
  48. GRB050826: Swift-BAT detection of a long burst
  49. GRB050824: MASTER final analysis of the OT observations
  50. Possible GRB050825:MASTER optical observations
  51. Swift-BAT trigger 152038 is definitely not a GRB
  52. GRB050824: CORRECTION to UVOT observing times
  53. Swift-BAT trigger 152038 is probably not a GRB
  54. GRB050824: Swift/UVOT detection of fading afterglow
  55. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  56. GRB050824, I-band imaging
  57. GRB050824: Radio Observations
  58. GRB 050824: Spectroscopic redshift from the VLT
  59. GRB 050822: refined XRT analysis
  60. GRB 050824: XRT refined analysis and possible afterglow detection
  61. GRB 050824: BAT refined analysis of a soft weak burst
  62. GRB050824: MASTER:OT decay
  63. GRB050824: MASTER observation OT
  64. GRB050805a: MASTER optical candidat
  65. GRB 050824: ROTSE-III Optical Limits
  66. GRB050824: Swift-BAT detection of a burst
  67. GRB 050824 optical candidate
  68. GRB050820A: RTT150 optical observations
  69. GRB050820a: PROMPT RcIc Observations
  70. GRB050815: Maidanak optical observation
  71. XRF050509c: Radio upper limits from GMRT
  72. VLT/UVES spectroscopy of GRB050820
  73. GRB050822: Swift/UVOT upper limits
  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. GRB050820B XMM-Newton observation
  89. GRB 050820a: NIR Observations by WIRO
  90. GRB 050820B: Swift XRT position
  91. GRB050820B: Planned XMM-Newton observation
  92. SUBJECT: GRB050820B: Refined analysis of the Swift-BAT burst
  93. GRB050820B: BAT-Swift detection of a bright GRB
  94. Swift/UVOT photometry of GRB050820
  95. GRB050820: refined XRT analysis
  96. GRB 050820: Early RAPTOR detections
  97. GRB 050820 Swift-BAT refined analysis
  98. GRB 050820: P60 Temporal Decay Index
  99. GRB 050820: High Resolution Spectroscopy from Keck
  100. GRB050819: refined XRT analysis

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