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

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