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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 050820: Early RAPTOR detections
  2. GRB 050820 Swift-BAT refined analysis
  3. GRB 050820: P60 Temporal Decay Index
  4. GRB 050820: High Resolution Spectroscopy from Keck
  5. GRB050819: refined XRT analysis
  6. GRB050819: RTT150 optical observations
  7. GRB 050820: Swift detection of a GRB
  8. GRB050820: Optical afterglow from P60
  9. GRB 050819 Swift-BAT refined analysis
  10. GRB050819: Swift XRT position
  11. GRB050819: Swift-BAT detection of a weak burst
  12. Swift-BAT trigger 150993 is not a GRB
  13. Swift Trigger 150823 is HETE J1900.1-2455
  14. GRB 050817: Optical observations
  15. GRB 050815: Radio Observation
  16. GRB050814: Radio Observation
  17. GRB050817: Negative Optical Observations
  18. GRB050817: Swift-BAT Detection of a burst
  19. GRB 050814: continued fading
  20. GRB050815: Optical afterglow detection by Swift UVOT
  21. GRB050815: XRT refined analysis
  22. GRB 050813: Radio Observations
  23. GRB050815: Refined analysis of the Swift-BAT burst
  24. GRB 050815: ROTSE-III Optical Limits
  25. GRB050815: Swift XRT afterglow localization
  26. GRB050815: Swift-BAT detection of a burst
  27. GRB 050730: Third Epoch WSRT Radio Observations
  28. GRB050814: Fading red source
  29. GRB 050813: Gemini Spectra Revisited
  30. GRB050814: P60 Optical Afterglow Candidate
  31. GRB 050813: Non-fading of afterglow candidate
  32. GRB 050814: XRT refined analysis
  33. GRB050814: SWIFT/UVOT observation
  34. GRB050814: Refined analysis of the Swift-BAT burst
  35. GRB050813: Gemini Imaging
  36. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  37. GRB 050814: Swift XRT Afterglow Localization
  38. GRB 050814: Swift detection of a burst
  39. GRB 050813: Magellan detection of a high redshift galaxy cluster
  40. GRB050813: RTT150 optical observations
  41. GRB 050813: I-band observations
  42. GRB050813, SDSS pre-burst observations
  43. GRB 050813: KAIT optical limit
  44. GRB 050813: Swift-BAT refined analysis
  45. GRB 050813: Photometry of object in XRT error circle
  46. GRB050813: SWIFT/UVOT observation
  47. GRB 050813: Swift XRT afterglow localization
  48. RBO GRB 050714A and GRB 050716 observations
  49. GRB 050813: Possible Short Swift-BAT GRB
  50. GRB050813 (Swift 150139): P60 Observations
  51. Swift-BAT trigger 150131 is not a GRB
  52. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  53. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  54. GRB050803: CrAO optical observations, no OT candidate
  55. Detection of an intermediate burst from SGR 1806-20 on August 8
  56. GRB 050730: WSRT Radio Observations
  57. GRB 050803: PROMPT BVRcIc Observations
  58. GRB 050807: ROTSE-III Optical Limits
  59. GRB 050730, optical observation
  60. GRB050805b: CrAO optical limit
  61. GRB050805a : Null detection report
  62. GRB050730, optical observations
  63. GRB050803, optical observations
  64. Swift-BAT trigger 149118 is very likely not a GRB
  65. Retraction of Swift Trigger 149131 (GRB 050805B)
  66. GRB 050805b: OHP optical limits
  67. GRB 050805b: TAROT optical limits
  68. GRB050805b: MASTER optical observations
  69. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  70. GRB050805a: MASTER optical candidat
  71. Swift-BAT trigger 149118 is probably not a GRB
  72. GRB050802: TNG optical observations
  73. GRB050803: Radio Observation
  74. GRB 050803: RTT150 optical observations
  75. GRB050801: Radio Observation
  76. GRB050730: Radio Detection
  77. GRB050803: CrAO optical observations, possible OT candidate
  78. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  79. GRB 050803: Keck Observations
  80. GRB 050803: Swift-BAT refined analysis
  81. GRB 050802.422: Fading of the afterglow and detection of the host
  82. GRB050803: MASTER further analys
  83. GRB 050803, optical observations
  84. GRB 050803: Magellan Observations
  85. GRB 050803: early Swift XRT analysis results
  86. GRB 050803: TAROT optical limits
  87. GRB050803: MASTER optical observations
  88. GRB050802: Tentative absorption redshift
  89. GRB050803: Swift-BAT detection of a very long burst
  90. GCN GRB observation 050713A
  91. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  92. GRB 050802: Swift/UVOT optical and UV detections
  93. GRB050802: CrAO optical observations
  94. GRB050801: Unchanged decay slope
  95. GRB050802 radio non-detection
  96. GRB 050730: OHP optical observations
  97. GRB 050802: early Swift XRT analysis results
  98. GRB 050802: Swift/UVOT observations
  99. GRB 050802 : Lulin Optical follow-up observation
  100. GRB 050802: Swift-BAT refined analysis

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