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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

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

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