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

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