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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"

45623 results found.

  1. GRB 050820: Swift detection of a GRB
  2. GRB050820: Optical afterglow from P60
  3. GRB 050819 Swift-BAT refined analysis
  4. GRB050819: Swift XRT position
  5. GRB050819: Swift-BAT detection of a weak burst
  6. Swift-BAT trigger 150993 is not a GRB
  7. Swift Trigger 150823 is HETE J1900.1-2455
  8. GRB 050817: Optical observations
  9. GRB 050815: Radio Observation
  10. GRB050814: Radio Observation
  11. GRB050817: Negative Optical Observations
  12. GRB050817: Swift-BAT Detection of a burst
  13. GRB 050814: continued fading
  14. GRB050815: Optical afterglow detection by Swift UVOT
  15. GRB050815: XRT refined analysis
  16. GRB 050813: Radio Observations
  17. GRB050815: Refined analysis of the Swift-BAT burst
  18. GRB 050815: ROTSE-III Optical Limits
  19. GRB050815: Swift XRT afterglow localization
  20. GRB050815: Swift-BAT detection of a burst
  21. GRB 050730: Third Epoch WSRT Radio Observations
  22. GRB050814: Fading red source
  23. GRB 050813: Gemini Spectra Revisited
  24. GRB050814: P60 Optical Afterglow Candidate
  25. GRB 050813: Non-fading of afterglow candidate
  26. GRB 050814: XRT refined analysis
  27. GRB050814: SWIFT/UVOT observation
  28. GRB050814: Refined analysis of the Swift-BAT burst
  29. GRB050813: Gemini Imaging
  30. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  31. GRB 050814: Swift XRT Afterglow Localization
  32. GRB 050814: Swift detection of a burst
  33. GRB 050813: Magellan detection of a high redshift galaxy cluster
  34. GRB050813: RTT150 optical observations
  35. GRB 050813: I-band observations
  36. GRB050813, SDSS pre-burst observations
  37. GRB 050813: KAIT optical limit
  38. GRB 050813: Swift-BAT refined analysis
  39. GRB 050813: Photometry of object in XRT error circle
  40. GRB050813: SWIFT/UVOT observation
  41. GRB 050813: Swift XRT afterglow localization
  42. RBO GRB 050714A and GRB 050716 observations
  43. GRB 050813: Possible Short Swift-BAT GRB
  44. GRB050813 (Swift 150139): P60 Observations
  45. Swift-BAT trigger 150131 is not a GRB
  46. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  47. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  48. GRB050803: CrAO optical observations, no OT candidate
  49. Detection of an intermediate burst from SGR 1806-20 on August 8
  50. GRB 050730: WSRT Radio Observations
  51. GRB 050803: PROMPT BVRcIc Observations
  52. GRB 050807: ROTSE-III Optical Limits
  53. GRB 050730, optical observation
  54. GRB050805b: CrAO optical limit
  55. GRB050805a : Null detection report
  56. GRB050730, optical observations
  57. GRB050803, optical observations
  58. Swift-BAT trigger 149118 is very likely not a GRB
  59. Retraction of Swift Trigger 149131 (GRB 050805B)
  60. GRB 050805b: OHP optical limits
  61. GRB 050805b: TAROT optical limits
  62. GRB050805b: MASTER optical observations
  63. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  64. GRB050805a: MASTER optical candidat
  65. Swift-BAT trigger 149118 is probably not a GRB
  66. GRB050802: TNG optical observations
  67. GRB050803: Radio Observation
  68. GRB 050803: RTT150 optical observations
  69. GRB050801: Radio Observation
  70. GRB050730: Radio Detection
  71. GRB050803: CrAO optical observations, possible OT candidate
  72. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  73. GRB 050803: Keck Observations
  74. GRB 050803: Swift-BAT refined analysis
  75. GRB 050802.422: Fading of the afterglow and detection of the host
  76. GRB050803: MASTER further analys
  77. GRB 050803, optical observations
  78. GRB 050803: Magellan Observations
  79. GRB 050803: early Swift XRT analysis results
  80. GRB 050803: TAROT optical limits
  81. GRB050803: MASTER optical observations
  82. GRB050802: Tentative absorption redshift
  83. GRB050803: Swift-BAT detection of a very long burst
  84. GCN GRB observation 050713A
  85. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  86. GRB 050802: Swift/UVOT optical and UV detections
  87. GRB050802: CrAO optical observations
  88. GRB050801: Unchanged decay slope
  89. GRB050802 radio non-detection
  90. GRB 050730: OHP optical observations
  91. GRB 050802: early Swift XRT analysis results
  92. GRB 050802: Swift/UVOT observations
  93. GRB 050802 : Lulin Optical follow-up observation
  94. GRB 050802: Swift-BAT refined analysis
  95. GRB050801: Optical photometry and decay index
  96. GRB 050802: XRT position
  97. GRB 050802: Swift Gamma-ray Burst
  98. GRB050801: Swift/UVOT Optical and UV detections
  99. GRB 050730: Preliminary Analysis of MIKE Spectrum
  100. GCN 050801: early Swift XRT analysis results

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