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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"

26324 results found.

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

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