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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. GRB050820B: Refined analysis of the Swift-BAT burst
  2. GRB050820B: BAT-Swift detection of a bright GRB
  3. Swift/UVOT photometry of GRB050820
  4. GRB050820: refined XRT analysis
  5. GRB 050820: Early RAPTOR detections
  6. GRB 050820 Swift-BAT refined analysis
  7. GRB 050820: P60 Temporal Decay Index
  8. GRB 050820: High Resolution Spectroscopy from Keck
  9. GRB050819: refined XRT analysis
  10. GRB050819: RTT150 optical observations
  11. GRB 050820: Swift detection of a GRB
  12. GRB050820: Optical afterglow from P60
  13. GRB 050819 Swift-BAT refined analysis
  14. GRB050819: Swift XRT position
  15. GRB050819: Swift-BAT detection of a weak burst
  16. Swift-BAT trigger 150993 is not a GRB
  17. Swift Trigger 150823 is HETE J1900.1-2455
  18. GRB 050817: Optical observations
  19. GRB 050815: Radio Observation
  20. GRB050814: Radio Observation
  21. GRB050817: Negative Optical Observations
  22. GRB050817: Swift-BAT Detection of a burst
  23. GRB 050814: continued fading
  24. GRB050815: Optical afterglow detection by Swift UVOT
  25. GRB050815: XRT refined analysis
  26. GRB 050813: Radio Observations
  27. GRB050815: Refined analysis of the Swift-BAT burst
  28. GRB 050815: ROTSE-III Optical Limits
  29. GRB050815: Swift XRT afterglow localization
  30. GRB050815: Swift-BAT detection of a burst
  31. GRB 050730: Third Epoch WSRT Radio Observations
  32. GRB050814: Fading red source
  33. GRB 050813: Gemini Spectra Revisited
  34. GRB050814: P60 Optical Afterglow Candidate
  35. GRB 050813: Non-fading of afterglow candidate
  36. GRB 050814: XRT refined analysis
  37. GRB050814: SWIFT/UVOT observation
  38. GRB050814: Refined analysis of the Swift-BAT burst
  39. GRB050813: Gemini Imaging
  40. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  41. GRB 050814: Swift XRT Afterglow Localization
  42. GRB 050814: Swift detection of a burst
  43. GRB 050813: Magellan detection of a high redshift galaxy cluster
  44. GRB050813: RTT150 optical observations
  45. GRB 050813: I-band observations
  46. GRB050813, SDSS pre-burst observations
  47. GRB 050813: KAIT optical limit
  48. GRB 050813: Swift-BAT refined analysis
  49. GRB 050813: Photometry of object in XRT error circle
  50. GRB050813: SWIFT/UVOT observation
  51. GRB 050813: Swift XRT afterglow localization
  52. RBO GRB 050714A and GRB 050716 observations
  53. GRB 050813: Possible Short Swift-BAT GRB
  54. GRB050813 (Swift 150139): P60 Observations
  55. Swift-BAT trigger 150131 is not a GRB
  56. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  57. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  58. GRB050803: CrAO optical observations, no OT candidate
  59. Detection of an intermediate burst from SGR 1806-20 on August 8
  60. GRB 050730: WSRT Radio Observations
  61. GRB 050803: PROMPT BVRcIc Observations
  62. GRB 050807: ROTSE-III Optical Limits
  63. GRB 050730, optical observation
  64. GRB050805b: CrAO optical limit
  65. GRB050805a : Null detection report
  66. GRB050730, optical observations
  67. GRB050803, optical observations
  68. Swift-BAT trigger 149118 is very likely not a GRB
  69. Retraction of Swift Trigger 149131 (GRB 050805B)
  70. GRB 050805b: OHP optical limits
  71. GRB 050805b: TAROT optical limits
  72. GRB050805b: MASTER optical observations
  73. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  74. GRB050805a: MASTER optical candidat
  75. Swift-BAT trigger 149118 is probably not a GRB
  76. GRB050802: TNG optical observations
  77. GRB050803: Radio Observation
  78. GRB 050803: RTT150 optical observations
  79. GRB050801: Radio Observation
  80. GRB050730: Radio Detection
  81. GRB050803: CrAO optical observations, possible OT candidate
  82. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  83. GRB 050803: Keck Observations
  84. GRB 050803: Swift-BAT refined analysis
  85. GRB 050802.422: Fading of the afterglow and detection of the host
  86. GRB050803: MASTER further analys
  87. GRB 050803, optical observations
  88. GRB 050803: Magellan Observations
  89. GRB 050803: early Swift XRT analysis results
  90. GRB 050803: TAROT optical limits
  91. GRB050803: MASTER optical observations
  92. GRB050802: Tentative absorption redshift
  93. GRB050803: Swift-BAT detection of a very long burst
  94. GCN GRB observation 050713A
  95. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  96. GRB 050802: Swift/UVOT optical and UV detections
  97. GRB050802: CrAO optical observations
  98. GRB050801: Unchanged decay slope
  99. GRB050802 radio non-detection
  100. GRB 050730: OHP optical observations

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