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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"

35995 results found.

  1. GRB050209: REM optical observations
  2. GRB 050209 I-band observation
  3. GRB 050209 Optical observations
  4. GRB050209: P60 Optical Observations
  5. GRB050209 (=U11568): A Long GRB Detected by HETE
  6. GRB 050209: Optical observation
  7. GRB 050128: Radio observations
  8. Further analysis of the short Swift-BAT GRB 050202
  9. GRB 050202: Second epoch radio observations
  10. GRB 050129: Optical observations
  11. GRB050202: Radio Observations
  12. GRB 050202: Optical observations with LCO40
  13. GRB 050202: Short burst detected by Swift-BAT
  14. GRB 050128 Optical observation with REM
  15. GRB 050129: a weak long GRB detected with INTEGRAL
  16. GRB050128: Faulkes Telescope South observations
  17. GRB 050124: Radio Observations
  18. GRB 050128: near-infrared observations with REM
  19. GRB050128,optical observations
  20. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  21. GRB 050126: Radio Observations
  22. GRB050128 Swift-BAT observations
  23. GRB 050128: Swift XRT prompt afterglow position
  24. GRB 050124: K-band afterglow observations
  25. GRB050126: MASTER optical limit for KECK OT
  26. GRB050126: MASTER optical observations
  27. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  28. GRB 050126: Prompt XRT detection and localization
  29. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  30. GRB 050124, SMARTS optical/IR observations
  31. GRB 050117a: Radio Observations
  32. GRB 050124 I-band observation
  33. GRB 050124: NIR Candidates from Keck/NIRC
  34. GRB050124,optical observation
  35. GRB 050124 : Lulin R-band follow-up observation
  36. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  37. GRB 050123 : I-band follow-up observation
  38. GRB050123: optical limit 1.8h before GRB
  39. GRB050123,optical observation
  40. GRB 050123: KAIT observations
  41. GRB050123: P60 Observations
  42. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  43. CFHTLS optical transient unlikely to be a GRB
  44. Unusual optical transient (GRB ???)
  45. GRB050117a: Radio Observations
  46. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  47. GRB 050117, I-band observations
  48. GRB 050117: Optical observation
  49. GRB050117: Refined XRT position
  50. GRB050117: MASTER optical observations
  51. MASTER:GRB050117 SWIFT
  52. GRB050117: Swift-BAT detection of a long multi-peaked burst
  53. Triangulation of Short Hard GRB050112 (large error box)
  54. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  55. SGR 1806-20 and extragalactic short-duration GRBs
  56. SGR 1806-20: Temporal and Spectral behavior of radio transient
  57. SGR 1806-20, RHESSI observations of the 041227 giant flare
  58. SGR1806: Detection of a Sudden Ionospheric Disturbance
  59. GRB 041217: Optical observations
  60. GRB041219, early time observations
  61. IPN localization of giant flare from SGR1806-20
  62. GRB041219; RXTE ASM Observations
  63. NIR Observations of GRB 041219
  64. GRB041223: decay of the afterglow
  65. GRB 041224: near-infrared observations with REM
  66. GRB 041223: XRT afterglow spectrum and light curve
  67. GRB 041223 Fluence measured by Swift-BAT
  68. GRB041223: optical and NIR observations with REM
  69. GRB 041219: TAROT optical observations
  70. GRB 041218: TAROT optical observations
  71. GRB 041223: J-band observations of the afterglow
  72. GRB 041223: Detection of Optical Transient with LCO40
  73. GRB 041219c: PROMPT Observations
  74. GRB 041218: optical observations
  75. GRB 041219: Second Epoch WSRT Radio Observations
  76. GRB 041219: WSRT Radio Afterglow Detection
  77. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  78. GRB 041218: Optical observations
  79. GRB 041219 : optical follow-up observations
  80. Deep RAPTOR observations during GRB 041219
  81. GRB 041218 Optical Observations
  82. GRB 041219 Optical Observations
  83. GRB041219c: Third Burst in One Day from Swift-BAT
  84. GRB041219: Optical Afterglow Detection
  85. GRB041219: Continued NIR Observations
  86. GRB 041219 ,optical observation
  87. GRB 041219: Radio Afterglow Detection
  88. GRB 041218 : Radio Observations
  89. GRB 041218: R-band optical observations
  90. GRB041219: Confirmed NIR Afterglow
  91. GRB041218: Continued P60 Optical Observations
  92. GRB 041218: Optical Observation
  93. GRB 041219: Infrared Afterglow Candidate
  94. GRB041219, BVRcIc field calibration
  95. GRB 041219: Infrared Afterglow Candidate
  96. GRB041218, BVRcIc field calibration
  97. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  98. GRB041219: P60 Optical Observations
  99. GRB 041219 - A long GRB detected by INTEGRAL
  100. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger

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