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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"

26422 results found.

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

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