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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"

25052 results found.

  1. GRB 050128: Radio observations
  2. GRB 050202: Short burst detected by Swift-BAT
  3. GRB 050128 Optical observation with REM
  4. GRB050128: Faulkes Telescope South observations
  5. GRB 050124: Radio Observations
  6. GRB 050128: near-infrared observations with REM
  7. GRB050128,optical observations
  8. GRB050128 Swift-BAT observations
  9. GRB 050128: Swift XRT prompt afterglow position
  10. GRB050126: MASTER optical limit for KECK OT
  11. GRB050126: Burst Parameters Measured by BAT
  12. GRB050126: MASTER optical observations
  13. GRB 050117a: Radio Observations
  14. GRB 050124 I-band observation
  15. GRB050124,optical observation
  16. GRB050124: Updated Swift XRT Position and Fluxes
  17. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  18. GRB050124: Refined BAT position, spectral and fluence information
  19. GRB050123: optical limit 1.8h before GRB
  20. GRB050123,optical observation
  21. GRB 050123: KAIT observations
  22. CFHTLS optical transient unlikely to be a GRB
  23. Unusual optical transient (GRB ???)
  24. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  25. GRB050117b: Swift-BAT detection of a weak burst
  26. GRB 050117, I-band observations
  27. GRB050117: Refined XRT position
  28. GRB050117: MASTER optical observations
  29. MASTER:GRB050117 SWIFT
  30. GRB050117: Swift XRT Position
  31. Triangulation of Short Hard GRB050112 (large error box)
  32. SGR1806-20: Swift-BAT observations of two additional bursts
  33. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  34. SGR 1806-20 and extragalactic short-duration GRBs
  35. Further ATCA observations of SGR 1806-20
  36. Fourth Epoch VLA observations of SGR 1806-20
  37. ATCA observations of SGR 1806-20
  38. SGR 1806-20, RHESSI observations of the 041227 giant flare
  39. Third epoch observations of SGR 1806-20 with VLA
  40. Second Epoch VLA observations of SGR 1806-20
  41. Second-epoch VLA observations of SGR 1806-20
  42. GRB 041217: Optical observations
  43. Detection of the SGR 1806-20 giant outburst back-scattered by the
  44. GRB041228: Swift-BAT detection of a burst
  45. GRB041219; RXTE ASM Observations
  46. GRB041226: Swift-BAT detection of a burst
  47. GRB041223: decay of the afterglow
  48. GRB 041224: near-infrared observations with REM
  49. GRB 041223 Fluence measured by Swift-BAT
  50. GRB041223: optical and NIR observations with REM
  51. GRB 041219: TAROT optical observations
  52. GRB 041218: TAROT optical observations
  53. GRB 041223: J-band observations of the afterglow
  54. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  55. GRB 041219c: PROMPT Observations
  56. GRB041223: Swift-BAT detection of a bright long burst
  57. GRB 041218: optical observations
  58. GRB 041219 : optical follow-up observations
  59. GRB041220: Swift-BAT burst
  60. GRB 041218 Optical Observations
  61. GRB041219c: Third Burst in One Day from Swift-BAT
  62. GRB041219: Continued NIR Observations
  63. GRB041219b: A Swift-BAT burst
  64. GRB 041219 ,optical observation
  65. GRB 041219: Radio Afterglow Detection
  66. GRB 041218 : Radio Observations
  67. GRB 041218: R-band optical observations
  68. GRB041218: optical observations
  69. GRB041219: Confirmed NIR Afterglow
  70. GRB041218: Continued P60 Optical Observations
  71. Swift-BAT detection of the bright long burst GRB041219
  72. GRB 041219: Infrared Afterglow Candidate
  73. GRB041219, BVRcIc field calibration
  74. GRB 041219: Infrared Afterglow Candidate
  75. GRB041218, BVRcIc field calibration
  76. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  77. GRB 041219 - A long GRB detected by INTEGRAL
  78. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  79. GRB 041217: PROMPT Observations
  80. GRB041217: optical limit 30 min after GRB
  81. GRB 041217: LCO40 Optical Observations and Possible Candidates
  82. GRB041217: NIR and optical observations with REM
  83. GRB041217: Infrared Observations
  84. GRB041217: The First GRB Located On-Board Swift
  85. GRB041211: Faulkes Telescope continued optical monitoring
  86. Optical transient (GRB?) in Lynx
  87. GRB041211: RAPTOR observations
  88. GRB041211: Ashra Prototype optical observation
  89. GRB041211, Faulkes Telescope optical observation
  90. GRB041211, BVRcIc field calibration
  91. GRB041211,optical observation
  92. GRB 041211: Infrared Observations
  93. GRB 041211: KAIT observations
  94. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  95. GRB970815: Discovery of Optical Afterglow
  96. Triangulation of short GRB 041116 (large error box)
  97. GRB 040924: Afterglow Color
  98. GRB 041006: GETS Optical Afterglow Observation
  99. GRB 041006: Optical Observations
  100. GRB041006, late-time optical photometry

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