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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"
  1. GRB 050319: Detection of Possible Optical Counterpart
  2. GRB 050318: Swift/UVOT detection of afterglow emission
  3. GRB 050318: Magellan optical afterglow identification
  4. GRB050318: Swift XRT position
  5. RXTE Observations of GRB050318
  6. Swift-BAT detection of GRB 050318
  7. GRB 050315, SMARTS optical afterglow decay
  8. GRB050223: analysis of the XMM-Newton observation
  9. GRB050316: MASTER before, simultanious and follow up optical
  10. GRB 050306: ROTSE-III early limits
  11. GRB050316: MASTER optical observations
  12. GRB 050315: Swift-BAT further refined analysis
  13. GRB 050315, SMARTS optical/IR afterglow observations
  14. GRB 050315 I-band observations
  15. GRB050315: Radio afterglow
  16. GRB 050315: Absorption redshift
  17. GRB 050315: Optical afterglow identification
  18. GRB050315: Swift-BAT Refined analysis
  19. Non-detection of GRB050315 in ATCA Radio Observations
  20. GRB 050315: Swift XRT Position
  21. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  22. GRB 050315: Early Observations with Swift/UVOT
  23. Swift-BAT detection of GRB 050315
  24. GRB050223: No XMM-Newton OM detection of afterglow emission
  25. GRB 050306: Radio Observations
  26. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  27. GRB050309: CONCAM pre-trigger and trigger coincident optical
  28. GRB 050306: optical afterglow
  29. GRB 050126: Redshift determination
  30. Swift-BAT trigger 107873: No Swift XRT counterpart
  31. GRB 050306: Confirmation of X-ray afterglow
  32. GRB 050309, Early optical limits from RAPTOR
  33. GRB 050306: further TAROT optical data
  34. GRB050309: Early optical limit from P60
  35. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  36. GRB 050309 : Lulin R-band observation
  37. Swift 107873: P60 Optical Observations
  38. GRB 050306: CORRECTION to date of observation
  39. GRB 050306: R-band observations
  40. GRB 050306: No Swift UVOT Optical Counterpart Detected
  41. GRB 050306: REM optical-infrared observations
  42. GRB 050306: Possible X-ray Afterglow Position from the Swift
  43. Swift trigger 107518: optical observation
  44. GRB 050306: TAROT optical observations
  45. GRB 050306,optical observation
  46. GRB 050306: Swift-BAT detection of a long burst
  47. Ongoing activity of SGR 1806-20 after the giant flare
  48. GRB050215B: Late-Time Swift UVOT Observations
  49. GRB 050126: Confirmation of the NIR afterglow candidate
  50. PROMPT VRcIc Observations of GRB 050223
  51. XRF/GRB 050215B: Radio Observations
  52. XMM-Newton Images of GRB 050223
  53. GRB 050219b: candidate NIR afterglow
  54. IBAS GRB Alert #2321
  55. Confirmed XRF nature for GRB050215b
  56. GRB 050223: optical observations
  57. GRB050223 XMM-Newton observation
  58. INTEGRAL detection of GRB 050223
  59. GRB 050223 : Planned XMM-Newton observation
  60. GRB050223: No Swift UVOT Detection of Afterglow Emission
  61. GRB050223: ROTSE-III Optical Observations
  62. GRB 050223 Swift/BAT detection of a burst
  63. GRB 050223: Swift XRT Position
  64. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  65. GRB050219b: CORRECTION to time of UVOT observations
  66. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  67. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  68. GRB 050219b: CORRECTION to refined XRT position
  69. GRB 050219a: Optical observations from LCO
  70. GRB 050219b: Optical and near-IR observations from LCO
  71. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  72. GRB 050219b: Refined XRT position
  73. GRB 050219b: Swift-BAT detection of a burst
  74. GRB 050219b: CORRECTION: Swift XRT Position
  75. GRB 050219b: Swift XRT Position
  76. GRB 050219a, optical observations
  77. GRB 050219a: Refined XRT position
  78. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  79. GRB 050219: Swift-BAT detection of a burst
  80. GRB050215b: Swift UVOT Detection of Afterglow Emission
  81. GRB 050219: Prompt X-ray position
  82. GRB 050215B: Radio Observations
  83. GRB 050215b: XRT confirmation of IR afterglow candidate
  84. GRB050215b: P60 Optical Observations
  85. GRB 050215b: Swift XRT Source Variability
  86. GRB 050215B: candidate afterglow
  87. GRB 050215b : Lulin follow-up observation
  88. GRB 050215b, BOOTES-2 simultaneous optical observations
  89. GRB 050215B: UKIRT K-band imaging
  90. GRB 050215b: Swift XRT Observations
  91. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  92. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  93. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  94. GRB 050215b, BOOTES-1B optical limit
  95. GRB050215B: ROTSE-III optical observations
  96. GRB050215A: ROTSE-III Optical Observations
  97. GRB050209: TAROT optical observations
  98. GRB 050209(=U11568): Duration and spectrum
  99. short/hard GRB 050202, optical observations
  100. GRB050209: REM optical observations

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