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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. GRB 050904: more VLT NIR observations
  2. GRB 050904: BOOTES early R-band observation
  3. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  4. GRB 050906: Bright galaxy in BAT error box
  5. GRB 050906: Swift/BAT Detection of a possible burst
  6. GRB 050904: More SOAR
  7. GRB 050904: photometric redshift
  8. GRB 050904: Swift/UVOT observations
  9. GRB 050904: Afterglow Astrometry
  10. GRB 050904: NIR object inside the XRT error box
  11. GRB 050904: early Swift XRT analysis results
  12. GRB 050904: SOAR YJ and PROMPT Ic Observations
  13. GRB 050904: BAT refined analysis of partial data set
  14. GRB 050904: TAROT optical measurements
  15. GRB050904: Optical Observations
  16. GRB 050904: Environmental Constraints
  17. GRB 050904: Possible High-Redshift GRB
  18. GRB 050904: SOAR/PROMPT Observations
  19. GRB050904: P60 Observations
  20. GRB 050904: TAROT optical limits
  21. GRB050904: Swift-BAT detection of a probable burst
  22. Swift-BAT triggers 153461-153465 are not GRBs
  23. Retraction of Swift-BAT trigger #153355
  24. GRB 050824: MDM Observations
  25. GRB 050827: Swift XRT preliminary analysis results
  26. IBAS Alerts 2641 and 2642: not a real GRB
  27. Swift Trigger #152652 is not a GRB
  28. GRB 050827 : OSN 1.5m optical observations
  29. GRB 050827: P200 NIR Observations
  30. GRB050827: Swift/UVOT upper limits
  31. GRB 050827: Optical Limit
  32. GRB 050827: XRT possible afterglow detection
  33. GRB 050826 : Lulin R band observation
  34. GRB050824: Maidanak optical limits
  35. GRB050820A: RTT150 optical observations
  36. GRB050827: RTT150 optical observations
  37. GRB 050827: Swift-BAT refined analysis
  38. GRB050827: Swift-BAT detection of a burst
  39. Subaru Observations of GRB050724
  40. GRB 050826: Optical Candidate
  41. GRB050824, HETE-2 Observation
  42. GRB 050826: Swift XRT preliminary analysis results
  43. GRB 050826: BAT refined analysis
  44. GRB050826: Swift/UVOT early upper limits
  45. GRB050824: First 2 hours of power low optical decay?
  46. GRB 050826: Swift XRT position
  47. GRB050826: Swift-BAT detection of a long burst
  48. GRB050824: MASTER final analysis of the OT observations
  49. Possible GRB050825:MASTER optical observations
  50. Swift-BAT trigger 152038 is definitely not a GRB
  51. GRB050824: CORRECTION to UVOT observing times
  52. Swift-BAT trigger 152038 is probably not a GRB
  53. GRB050824: Swift/UVOT detection of fading afterglow
  54. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  55. GRB050824, I-band imaging
  56. GRB050824: Radio Observations
  57. GRB 050824: Spectroscopic redshift from the VLT
  58. GRB 050822: refined XRT analysis
  59. GRB 050824: XRT refined analysis and possible afterglow detection
  60. GRB 050824: BAT refined analysis of a soft weak burst
  61. GRB050824: MASTER:OT decay
  62. GRB050824: MASTER observation OT
  63. GRB050805a: MASTER optical candidat
  64. GRB 050824: ROTSE-III Optical Limits
  65. GRB050824: Swift-BAT detection of a burst
  66. GRB 050824 optical candidate
  67. GRB050820A: RTT150 optical observations
  68. GRB050820a: PROMPT RcIc Observations
  69. GRB050815: Maidanak optical observation
  70. XRF050509c: Radio upper limits from GMRT
  71. VLT/UVES spectroscopy of GRB050820
  72. GRB050822: Swift/UVOT upper limits
  73. GRB 050820A BAT observations of second, larger episode of emission
  74. GRB050813: Maidanak I-band observations
  75. GRB 050822: Swift-BAT refined analysis
  76. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  77. GRB050820B at FRAM
  78. GRB050820A: RTT150 optical observations
  79. GRB 050820a - corrections to GCN 3846
  80. Swift/UVOT UV Photometry of GRB 050820B
  81. GRB 050822: ROTSE-III Prompt Optical Limits
  82. GRB 050822: Swift detection of a long burst
  83. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  84. GRB050820A: Radio Observation
  85. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  86. GRB050820a BVRcIc field photometry
  87. GRB050820B XMM-Newton observation
  88. GRB 050820a: NIR Observations by WIRO
  89. GRB 050820B: Swift XRT position
  90. GRB050820B: Planned XMM-Newton observation
  91. SUBJECT: GRB050820B: Refined analysis of the Swift-BAT burst
  92. GRB050820B: BAT-Swift detection of a bright GRB
  93. Swift/UVOT photometry of GRB050820
  94. GRB050820: refined XRT analysis
  95. GRB 050820: Early RAPTOR detections
  96. GRB 050820 Swift-BAT refined analysis
  97. GRB 050820: P60 Temporal Decay Index
  98. GRB 050820: High Resolution Spectroscopy from Keck
  99. GRB050819: refined XRT analysis
  100. GRB050819: RTT150 optical observations

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