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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 051109B: Swift-BAT refined analysis
  2. GRB 051109B: ROTSE-III Optical Limits
  3. GRB 051109A: Swift-UVOT Observations
  4. IPN triangulation and Konus spectrum of the short/soft GRB051107 (large
  5. GRB051109B: no UVOT source detected
  6. GRB051109B: XRT refined analysis
  7. GRB 051109B : Lulin Optical Observations
  8. GRB 051109A : Lulin BVRI Optical afterglow observation
  9. GRB051109A: further steepening in the X-ray light curve
  10. GRB051109A: XRT refined analysis
  11. GRB 051109a: BOOTES R & I-band detection of the early afterglow
  12. GRB051109B: XRT position
  13. GRB 051109B: Super-LOTIS Observations
  14. GRB 051109B Kiso optical follow-up observation
  15. GRB051105B: REM Optical observation
  16. GRB 051109B: Swift detection of a burst
  17. GRB 051109: HET Optical Spectrum and Absorption Redshift
  18. GRB 051109: PROMPT Detections
  19. GRB 051109: Rc and Ic observations
  20. GRB051109: Early Super-LOTIS Detection
  21. GRB 051109: Swift-BAT refined analysis
  22. GRB 051109a: IR Photometry and Astrometry
  23. GRB 051109a: MDM Observations
  24. GRB 051109A: ROTSE-III Decline rate for Optical Counterpart
  25. GRB051109: Swift detection of a burst
  26. GRB 051109a: IR Detections
  27. GRB 051109: ROTSE-III Detection of Possible Counterpart
  28. GRB051105B: Swift/XRT upper limit
  29. GRB051105B: Swift/UVOT upper limit
  30. GRB051103: optical observations
  31. GRB 051103, optical observations
  32. GRB051103: MASTER: OT limit and host galaxy candidates
  33. GRB051028: Swift-XRT refined analysis
  34. GRB 051105a, observation from Naini Tal and OSN
  35. GRB 051105A, 2nd epoch optical observations
  36. GRB 051105a: MDM Observations
  37. GRB 051105A: TNG optical observations
  38. GRB051105A: Swift/UVOT Observations
  39. GRB 051105A, radio observations
  40. GRB051103:_MASTER_optical_observations
  41. IPN triangulation and Konus spectrum of the bright short/hard GRB051103
  42. GRB 051105A, optical observations
  43. XRT observations of GRB 051105A
  44. GRB 051105: Swift-BAT improved refined analysis
  45. GRB 051105b: ART optical limits
  46. GRB051105B - A long GRB detected by INTEGRAL
  47. GRB 051105B (INTEGRAL 2701): Optical observation
  48. GRB 051105: Swift-BAT refined analysis
  49. GRB 051105: Optical limit
  50. GRB 051105: Swift detection of a short burst
  51. IBAS Alert 2700: Not a GRB
  52. GRB 051016B host spectroscopy and redshift
  53. GRB051016B: optical observation
  54. Recent GRB UBVRcIc field photometry
  55. Konus-Wind observation of GRB 051028
  56. GRB051028:MASTER correction and final results
  57. GRB 051022: RTT150 optical observations
  58. GRB 051021A: RTT150 optical observations
  59. GRB051028 SARA Observation
  60. GRB051028: optical observations
  61. GRB051028: Swift/UVOT upper limits
  62. GRB051028: confirmation of the afterglow
  63. GRB051028: WHT optical candidate
  64. GRB051028: Swift XRT Position
  65. GRB051028:MASTER observations
  66. GRB 051028 (=H3951): A GRB localized by HETE
  67. GRB051028:MASTER optical observations
  68. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  69. GRB051022: Swift XRT measurement of jet break
  70. SGR 1806-20: continued moderate activity seen with INTEGRAL
  71. GRB051021B: Swift/UVOT Upper limits
  72. GRB 051021, Optical Observations
  73. GRB 051022: XRT Refined Spectral and Temporal Analysis
  74. GRB 051022, refined optical astrometry
  75. Chandra Observations of GRB 051022
  76. GRB051012: Swift-XRT analysis
  77. GRB 051022 Chandra Observations scheduled
  78. GRB051021B: Swift XRT refined analysis
  79. GRB051021a: optical observations
  80. GRB 051022: WSRT Radio Detection
  81. GRB 051022, mm counterpart
  82. GRB051022: host galaxy redshift
  83. GRB 051022: Swift/UVOT Upper Limits
  84. GRB051022: Radio Counterpart
  85. GRB051022: IR observations
  86. GRB 051022: SOAR JKs Observations
  87. GRB051021A: Swift XRT refined analysis
  88. Konus-Wind observation of GRB 051022
  89. GRB051022: Optical Observations
  90. GRB 051022: Magellan NIR imaging
  91. GRB 051021: PROMPT RcIc Observations
  92. GRB051021b: Magellan IR Imaging
  93. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  94. GRB 051021: Correction
  95. GRB 051022, J & K-band observation
  96. GRB 051021, SMARTS optical/IR observations
  97. GRB051022: Swift XRT Position
  98. GRB 051021: P200 Ks Observations
  99. IPN triangulation of GRB051022 (=H3950)
  100. GRB 051021: MDM Upper Limit

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