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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"

27392 results found.

  1. WIRO observations in I of GRB 050908
  2. GRB 050906: Possible X-ray Counterpart
  3. GRB050908: Swift/UVOT Early upper limits
  4. GRB050908 : Swift-XRT refined analysis
  5. GRB 050908: Swift-BAT refined analysis
  6. GRB 050908: Optical observations
  7. GRB 050908: Optical Observations
  8. GRB 050908: Swift detection of a burst
  9. GRB 050906: Optical observations at the Very Large Telescope
  10. GRB 050904 BAT refined analysis of complete data set
  11. GRB 050904: Subaru Optical Spectroscopy
  12. GRB 050906: MARGE Optical Limits
  13. GRB 050906: Swift-BAT refined analysis
  14. GRB 050906: Swift XRT upper limit
  15. GRB 050906: Radio Observations
  16. GRB 050904: Keck I-band Imaging
  17. GRB050906: P60 Observations
  18. GRB 050904: more VLT NIR observations
  19. GRB 050904: photometric redshift
  20. GRB 050904: Swift/UVOT observations
  21. GRB 050904: NIR object inside the XRT error box
  22. GRB 050904: early Swift XRT analysis results
  23. GRB 050904: SOAR YJ and PROMPT Ic Observations
  24. GRB050904: Optical Observations
  25. GRB050904: P60 Observations
  26. GRB 050904: TAROT optical limits
  27. GRB 050827 : OSN 1.5m optical observations
  28. GRB 050827: P200 NIR Observations
  29. GRB050827: Swift/UVOT upper limits
  30. GRB 050827: Optical Limit
  31. GRB 050827: XRT possible afterglow detection
  32. GRB 050826 : Lulin R band observation
  33. GRB050824: Maidanak optical limits
  34. GRB 050827: Swift-BAT refined analysis
  35. Subaru Observations of GRB050724
  36. GRB 050826: Optical Candidate
  37. GRB 050826: Swift XRT preliminary analysis results
  38. GRB 050826: BAT refined analysis
  39. GRB050826: Swift/UVOT early upper limits
  40. GRB050826: Swift-BAT detection of a long burst
  41. GRB050824: MASTER final analysis of the OT observations
  42. Swift-BAT trigger 152038 is probably not a GRB
  43. GRB 050824: XRT refined analysis and possible afterglow detection
  44. GRB 050824: BAT refined analysis of a soft weak burst
  45. GRB050824: MASTER:OT decay
  46. GRB050824: MASTER observation OT
  47. GRB050805a: MASTER optical candidat
  48. XRF050509c: Radio upper limits from GMRT
  49. GRB050822: Swift/UVOT upper limits
  50. GRB 050820A BAT observations of second, larger episode of emission
  51. GRB050813: Maidanak I-band observations
  52. GRB 050822: Swift-BAT refined analysis
  53. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  54. GRB050820B at FRAM
  55. Swift/UVOT UV Photometry of GRB 050820B
  56. GRB 050822: Swift detection of a long burst
  57. GRB050820a BVRcIc field photometry
  58. GRB050820B XMM-Newton observation
  59. GRB 050820a: NIR Observations by WIRO
  60. GRB 050820B: Swift XRT position
  61. GRB050820B: Refined analysis of the Swift-BAT burst
  62. GRB050820: refined XRT analysis
  63. GRB 050820 Swift-BAT refined analysis
  64. GRB050819: refined XRT analysis
  65. GRB 050820: Swift detection of a GRB
  66. GRB 050819 Swift-BAT refined analysis
  67. GRB050819: Swift-BAT detection of a weak burst
  68. GRB 050817: Optical observations
  69. GRB050817: Negative Optical Observations
  70. GRB 050814: continued fading
  71. GRB050815: Optical afterglow detection by Swift UVOT
  72. GRB050815: XRT refined analysis
  73. GRB050815: Refined analysis of the Swift-BAT burst
  74. GRB 050815: ROTSE-III Optical Limits
  75. GRB050815: Swift-BAT detection of a burst
  76. GRB050814: Fading red source
  77. GRB050814: P60 Optical Afterglow Candidate
  78. GRB 050813: Non-fading of afterglow candidate
  79. GRB 050814: XRT refined analysis
  80. GRB050814: SWIFT/UVOT observation
  81. GRB050814: Refined analysis of the Swift-BAT burst
  82. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  83. GRB 050814: Swift XRT Afterglow Localization
  84. GRB 050814: Swift detection of a burst
  85. GRB 050813: Magellan detection of a high redshift galaxy cluster
  86. GRB050813, SDSS pre-burst observations
  87. GRB 050813: Swift-BAT refined analysis
  88. GRB 050813: Photometry of object in XRT error circle
  89. GRB050813: SWIFT/UVOT observation
  90. GRB 050813: Swift XRT afterglow localization
  91. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  92. Detection of an intermediate burst from SGR 1806-20 on August 8
  93. GRB050805b: CrAO optical limit
  94. GRB050803, optical observations
  95. Retraction of Swift Trigger 149131 (GRB 050805B)
  96. GRB 050805b: OHP optical limits
  97. GRB 050805b: TAROT optical limits
  98. GRB050805b: MASTER optical observations
  99. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  100. GRB050805a: MASTER optical candidat

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