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

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