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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. GRB050817: Negative Optical Observations
  2. GRB050817: Swift-BAT Detection of a burst
  3. GRB 050814: continued fading
  4. GRB050815: Optical afterglow detection by Swift UVOT
  5. GRB050815: XRT refined analysis
  6. GRB 050813: Radio Observations
  7. GRB050815: Refined analysis of the Swift-BAT burst
  8. GRB 050815: ROTSE-III Optical Limits
  9. GRB050815: Swift XRT afterglow localization
  10. GRB050815: Swift-BAT detection of a burst
  11. GRB 050730: Third Epoch WSRT Radio Observations
  12. GRB050814: Fading red source
  13. GRB 050813: Gemini Spectra Revisited
  14. GRB050814: P60 Optical Afterglow Candidate
  15. GRB 050813: Non-fading of afterglow candidate
  16. GRB 050814: XRT refined analysis
  17. GRB050814: SWIFT/UVOT observation
  18. GRB050814: Refined analysis of the Swift-BAT burst
  19. GRB050813: Gemini Imaging
  20. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  21. GRB 050814: Swift XRT Afterglow Localization
  22. GRB 050814: Swift detection of a burst
  23. GRB 050813: Magellan detection of a high redshift galaxy cluster
  24. GRB050813: RTT150 optical observations
  25. GRB 050813: I-band observations
  26. GRB050813, SDSS pre-burst observations
  27. GRB 050813: KAIT optical limit
  28. GRB 050813: Swift-BAT refined analysis
  29. GRB 050813: Photometry of object in XRT error circle
  30. GRB050813: SWIFT/UVOT observation
  31. GRB 050813: Swift XRT afterglow localization
  32. RBO GRB 050714A and GRB 050716 observations
  33. GRB 050813: Possible Short Swift-BAT GRB
  34. GRB050813 (Swift 150139): P60 Observations
  35. Swift-BAT trigger 150131 is not a GRB
  36. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  37. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  38. GRB050803: CrAO optical observations, no OT candidate
  39. Detection of an intermediate burst from SGR 1806-20 on August 8
  40. GRB 050730: WSRT Radio Observations
  41. GRB 050803: PROMPT BVRcIc Observations
  42. GRB 050807: ROTSE-III Optical Limits
  43. GRB 050730, optical observation
  44. GRB050805b: CrAO optical limit
  45. GRB050805a : Null detection report
  46. GRB050730, optical observations
  47. GRB050803, optical observations
  48. Swift-BAT trigger 149118 is very likely not a GRB
  49. Retraction of Swift Trigger 149131 (GRB 050805B)
  50. GRB 050805b: OHP optical limits
  51. GRB 050805b: TAROT optical limits
  52. GRB050805b: MASTER optical observations
  53. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  54. GRB050805a: MASTER optical candidat
  55. Swift-BAT trigger 149118 is probably not a GRB
  56. GRB050802: TNG optical observations
  57. GRB050803: Radio Observation
  58. GRB 050803: RTT150 optical observations
  59. GRB050801: Radio Observation
  60. GRB050730: Radio Detection
  61. GRB050803: CrAO optical observations, possible OT candidate
  62. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  63. GRB 050803: Keck Observations
  64. GRB 050803: Swift-BAT refined analysis
  65. GRB 050802.422: Fading of the afterglow and detection of the host
  66. GRB050803: MASTER further analys
  67. GRB 050803, optical observations
  68. GRB 050803: Magellan Observations
  69. GRB 050803: early Swift XRT analysis results
  70. GRB 050803: TAROT optical limits
  71. GRB050803: MASTER optical observations
  72. GRB050802: Tentative absorption redshift
  73. GRB050803: Swift-BAT detection of a very long burst
  74. GCN GRB observation 050713A
  75. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  76. GRB 050802: Swift/UVOT optical and UV detections
  77. GRB050802: CrAO optical observations
  78. GRB050801: Unchanged decay slope
  79. GRB050802 radio non-detection
  80. GRB 050730: OHP optical observations
  81. GRB 050802: early Swift XRT analysis results
  82. GRB 050802: Swift/UVOT observations
  83. GRB 050802 : Lulin Optical follow-up observation
  84. GRB 050802: Swift-BAT refined analysis
  85. GRB050801: Optical photometry and decay index
  86. GRB 050802: XRT position
  87. GRB 050802: Swift Gamma-ray Burst
  88. GRB050801: Swift/UVOT Optical and UV detections
  89. GRB 050730: Preliminary Analysis of MIKE Spectrum
  90. GCN 050801: early Swift XRT analysis results
  91. GRB 050801: Swift-BAT refined analysis
  92. GRB 050801, SMARTS optical/IR afterglow observations
  93. GRB 050801, afterglow observations
  94. GRB 050730, corrected photometry and break?
  95. GRB 050801: ROTSE-III Early Afterglow Break
  96. GRB050801: Swift-BAT detection of a burst
  97. GRB050801: GCN XRT position is incorrect
  98. GRB 050801: ROTSE-III Detection of Possible Counterpart
  99. GRB 050730: XRT refined analysis
  100. Correction to GCN Circ 3476 on GRB050525A

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