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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"

26494 results found.

  1. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  2. Swift 107873: P60 Optical Observations
  3. GRB 050306: R-band observations
  4. GRB 050306: REM optical-infrared observations
  5. GRB 050306: Possible X-ray Afterglow Position from the Swift
  6. GRB 050306: TAROT optical observations
  7. GRB 050306,optical observation
  8. GRB 050306: Swift-BAT detection of a long burst
  9. Ongoing activity of SGR 1806-20 after the giant flare
  10. GRB050215B: Late-Time Swift UVOT Observations
  11. PROMPT VRcIc Observations of GRB 050223
  12. XMM-Newton Images of GRB 050223
  13. GRB 050219b: candidate NIR afterglow
  14. Confirmed XRF nature for GRB050215b
  15. GRB 050223: optical observations
  16. GRB050223 XMM-Newton observation
  17. GRB050223: ROTSE-III Optical Observations
  18. GRB 050223 Swift/BAT detection of a burst
  19. GRB 050223: Swift XRT Position
  20. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  21. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  22. GRB 050219a: Optical observations from LCO
  23. GRB 050219b: Optical and near-IR observations from LCO
  24. GRB 050219b: Swift-BAT detection of a burst
  25. GRB 050219b: CORRECTION: Swift XRT Position
  26. GRB 050219b: Swift XRT Position
  27. GRB 050219a, optical observations
  28. GRB 050219: Swift-BAT detection of a burst
  29. GRB 050215b: XRT confirmation of IR afterglow candidate
  30. GRB050215b: P60 Optical Observations
  31. GRB 050215b: Swift XRT Source Variability
  32. GRB 050215B: candidate afterglow
  33. GRB 050215b, BOOTES-2 simultaneous optical observations
  34. GRB 050215b, BOOTES-1B optical limit
  35. GRB050215A: ROTSE-III Optical Observations
  36. GRB050209: TAROT optical observations
  37. GRB 050209(=U11568): Duration and spectrum
  38. short/hard GRB 050202, optical observations
  39. GRB050209: REM optical observations
  40. GRB 050209 I-band observation
  41. GRB 050209 Optical observations
  42. GRB050209: P60 Optical Observations
  43. GRB 050128: Radio observations
  44. GRB 050202: Short burst detected by Swift-BAT
  45. GRB 050128 Optical observation with REM
  46. GRB050128: Faulkes Telescope South observations
  47. GRB 050124: Radio Observations
  48. GRB 050128: near-infrared observations with REM
  49. GRB050128,optical observations
  50. GRB050128 Swift-BAT observations
  51. GRB 050128: Swift XRT prompt afterglow position
  52. GRB050126: MASTER optical limit for KECK OT
  53. GRB050126: Burst Parameters Measured by BAT
  54. GRB050126: MASTER optical observations
  55. GRB 050117a: Radio Observations
  56. GRB 050124 I-band observation
  57. GRB050124,optical observation
  58. GRB050124: Updated Swift XRT Position and Fluxes
  59. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  60. GRB050124: Refined BAT position, spectral and fluence information
  61. GRB050123: optical limit 1.8h before GRB
  62. GRB050123,optical observation
  63. GRB 050123: KAIT observations
  64. CFHTLS optical transient unlikely to be a GRB
  65. Unusual optical transient (GRB ???)
  66. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  67. GRB050117b: Swift-BAT detection of a weak burst
  68. GRB 050117, I-band observations
  69. GRB050117: Refined XRT position
  70. GRB050117: MASTER optical observations
  71. MASTER:GRB050117 SWIFT
  72. GRB050117: Swift XRT Position
  73. Triangulation of Short Hard GRB050112 (large error box)
  74. SGR1806-20: Swift-BAT observations of two additional bursts
  75. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  76. SGR 1806-20 and extragalactic short-duration GRBs
  77. Further ATCA observations of SGR 1806-20
  78. Fourth Epoch VLA observations of SGR 1806-20
  79. ATCA observations of SGR 1806-20
  80. SGR 1806-20, RHESSI observations of the 041227 giant flare
  81. Third epoch observations of SGR 1806-20 with VLA
  82. Second Epoch VLA observations of SGR 1806-20
  83. Second-epoch VLA observations of SGR 1806-20
  84. GRB 041217: Optical observations
  85. Detection of the SGR 1806-20 giant outburst back-scattered by the
  86. GRB041228: Swift-BAT detection of a burst
  87. GRB041219; RXTE ASM Observations
  88. GRB041226: Swift-BAT detection of a burst
  89. GRB041223: decay of the afterglow
  90. GRB 041224: near-infrared observations with REM
  91. GRB 041223 Fluence measured by Swift-BAT
  92. GRB041223: optical and NIR observations with REM
  93. GRB 041219: TAROT optical observations
  94. GRB 041218: TAROT optical observations
  95. GRB 041223: J-band observations of the afterglow
  96. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  97. GRB 041219c: PROMPT Observations
  98. GRB041223: Swift-BAT detection of a bright long burst
  99. GRB 041218: optical observations
  100. GRB 041219 : optical follow-up observations

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