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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"

35983 results found.

  1. GRB 050319: Optical observation
  2. GRB 050319 : Confirmation of optical afterglow decay
  3. GRB 050319: Swift-BAT refined analysis
  4. GRB050319,optical observation
  5. Swift Detection of GRB 050319
  6. GRB 050319: Detection of Possible Optical Counterpart
  7. GRB 050318: Swift/UVOT detection of afterglow emission
  8. GRB 050318: Magellan optical afterglow identification
  9. GRB050318: Swift XRT position
  10. RXTE Observations of GRB050318
  11. Swift-BAT detection of GRB 050318
  12. GRB 050315, SMARTS optical afterglow decay
  13. GRB050316: MASTER before, simultanious and follow up optical
  14. GRB 050306: ROTSE-III early limits
  15. GRB050316: MASTER optical observations
  16. GRB 050315: Swift-BAT further refined analysis
  17. GRB 050315, SMARTS optical/IR afterglow observations
  18. GRB 050315 I-band observations
  19. GRB050315: Radio afterglow
  20. GRB 050315: Absorption redshift
  21. GRB 050315: Optical afterglow identification
  22. GRB050315: Swift-BAT Refined analysis
  23. Non-detection of GRB050315 in ATCA Radio Observations
  24. GRB 050315: Swift XRT Position
  25. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  26. GRB 050315: Early Observations with Swift/UVOT
  27. Swift-BAT detection of GRB 050315
  28. GRB 050306: Radio Observations
  29. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  30. GRB050309: CONCAM pre-trigger and trigger coincident optical
  31. GRB 050306: optical afterglow
  32. GRB 050126: Redshift determination
  33. Swift-BAT trigger 107873: No Swift XRT counterpart
  34. GRB 050306: Confirmation of X-ray afterglow
  35. GRB 050309, Early optical limits from RAPTOR
  36. GRB 050306: further TAROT optical data
  37. GRB050309: Early optical limit from P60
  38. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  39. GRB 050309 : Lulin R-band observation
  40. Swift 107873: P60 Optical Observations
  41. GRB 050306: CORRECTION to date of observation
  42. GRB 050306: R-band observations
  43. GRB 050306: No Swift UVOT Optical Counterpart Detected
  44. GRB 050306: REM optical-infrared observations
  45. GRB 050306: Possible X-ray Afterglow Position from the Swift
  46. Swift trigger 107518: optical observation
  47. GRB 050306: TAROT optical observations
  48. GRB 050306,optical observation
  49. GRB 050306: Swift-BAT detection of a long burst
  50. GRB 050126: Confirmation of the NIR afterglow candidate
  51. PROMPT VRcIc Observations of GRB 050223
  52. XRF/GRB 050215B: Radio Observations
  53. XMM-Newton Images of GRB 050223
  54. GRB 050219b: candidate NIR afterglow
  55. IBAS GRB Alert #2321
  56. GRB 050223: optical observations
  57. INTEGRAL detection of GRB 050223
  58. GRB 050223 : Planned XMM-Newton observation
  59. GRB050223: ROTSE-III Optical Observations
  60. GRB 050223 Swift/BAT detection of a burst
  61. GRB 050223: Swift XRT Position
  62. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  63. GRB 050219b: CORRECTION to refined XRT position
  64. GRB 050219a: Optical observations from LCO
  65. GRB 050219b: Optical and near-IR observations from LCO
  66. GRB 050219b: Refined XRT position
  67. GRB 050219b: Swift-BAT detection of a burst
  68. GRB 050219b: CORRECTION: Swift XRT Position
  69. GRB 050219b: Swift XRT Position
  70. GRB 050219a, optical observations
  71. GRB 050219a: Refined XRT position
  72. GRB 050219: Swift-BAT detection of a burst
  73. GRB050215b: Swift UVOT Detection of Afterglow Emission
  74. GRB 050219: Prompt X-ray position
  75. GRB 050215B: Radio Observations
  76. GRB 050215b: XRT confirmation of IR afterglow candidate
  77. GRB050215b: P60 Optical Observations
  78. GRB 050215b: Swift XRT Source Variability
  79. GRB 050215B: candidate afterglow
  80. GRB 050215b : Lulin follow-up observation
  81. GRB 050215b, BOOTES-2 simultaneous optical observations
  82. GRB 050215B: UKIRT K-band imaging
  83. GRB 050215b: Swift XRT Observations
  84. GRB 050215b, BOOTES-1B optical limit
  85. GRB050215A: ROTSE-III Optical Observations
  86. GRB050209: TAROT optical observations
  87. GRB 050209(=U11568): Duration and spectrum
  88. short/hard GRB 050202, optical observations
  89. GRB050209: REM optical observations
  90. GRB 050209 I-band observation
  91. GRB 050209 Optical observations
  92. GRB050209: P60 Optical Observations
  93. GRB050209 (=U11568): A Long GRB Detected by HETE
  94. GRB 050209: Optical observation
  95. GRB 050128: Radio observations
  96. Further analysis of the short Swift-BAT GRB 050202
  97. GRB 050202: Second epoch radio observations
  98. GRB 050129: Optical observations
  99. GRB050202: Radio Observations
  100. GRB 050202: Optical observations with LCO40

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