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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 060428b : Kiso R-band limit
  2. GRB060427:MASTER optical limit
  3. GRB 060428b: Optical afterglow candidate
  4. GRB060428A: Swift XRT Team refined analysis
  5. GRB 060428B: Swift detection of a burst
  6. GRB 060427: NIR observations
  7. GRB060427: Xinglong optical Observations
  8. GRB 060428: Swift detection of a burst
  9. GRB 060427: NOT observations
  10. GRB 060427: Swift/UVOT upper limits.
  11. GRB 060427: Refined analysis of the Swift-BAT burst
  12. GRB060427: Swift XRT Team refined analysis
  13. GRB060418: Swift XRT Team Further Refined Analysis
  14. GRB060425:MASTER survey observations
  15. GRB 060427, optical observation
  16. GRB 060427: Swift detection of a burst
  17. GRB 060425: IPN localization and KW spectrum of a short, hard burst
  18. An interactive program for GRB pseudo-redshift computations
  19. GRB060424: optical afterglow detection
  20. GRB060418: Further Analysis of MIKE Spectroscopy
  21. GRB 060424: Refined analysis of the Swift-BAT burst
  22. GRB 060424: Swift detection of a burst
  23. GRB 060421: TTT Observations
  24. OT 060420: Likely Not a New Cosmic Transient
  25. No OT 060420 in MASCOT images
  26. Swift-BAT detection of Mrk 421
  27. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  28. GRB060421: Swift/UVOT observations
  29. GRB 060421: Swift-BAT Refined Analysis
  30. GRB 060421: Swift-XRT refined analysis
  31. GRB 060418: prediction of t_break
  32. GRB060418: optical observations
  33. Konus-Wind observation of GRB 060418
  34. GRB(?)060421:MASTER optical limit
  35. GRB(?)060421 : XRT position
  36. Possible GRB060421: BART limits
  37. GRB(?) 060421: Swift detection of a burst
  38. Erratum of GCN 4983 for GRB 060418 IR follow-up
  39. GRB 060418 : IR afterglow observations
  40. GRB 060418 : Lulin Optical follow-up
  41. GRB 060418: JHKs PAIRITEL Observations of Afterglow
  42. GRB 060418: Radio Observations
  43. GRB060418, BVRcIc field calibration
  44. GRB060418: Swift/UVOT Observations
  45. GRB060418: Optical Observations
  46. GRB 060418: FRAM early afterglow observation
  47. GRB 060418: Refined Analysis of the Swift-BAT burst
  48. VLT/UVES observations of GRB060418
  49. GRB060418: Swift XRT Team Refined Analysis
  50. GRB 060418, SMARTS continuing afterglow observations
  51. GRB 060418: PROMPT Detections
  52. GRB 060418, SMARTS optical/IR afterglow observations
  53. GRB060418: Magellan/MIKE Spectroscopic Redshift
  54. GRB060418 : LT optical afterglow observation
  55. GRB 060418: REM candidate afterglow
  56. GRB 060418: Swift detection of a burst with bright x-ray and optical afterglow
  57. SGR 1900+14: Refined analysis of the Swift-BAT outburst
  58. GRB060413: Swift/UVOT upper limits
  59. GRB 060413: REM NIR Observations
  60. SGR 1900+14: Swift detection of an outburst
  61. GRB 060413: Refined analysis of the Swift-BAT burst
  62. GRB 060413: Watcher UBVR observations
  63. GRB 060413: XRT refined analysis
  64. GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data
  65. GRB 060413: Swift detection of a burst
  66. GRB060403: optical observations
  67. GRB 060403 Optical observations
  68. GRB 060403: MITSuME optical observation
  69. GRB060403: Optical Limit
  70. GRB060403: XRT refined analysis
  71. GRB 060403: Swift/UVOT upper limits
  72. HETE Triggers H4043 and H4044 Not Due to New Cosmic Source
  73. SGR 1900+14: BAT observations
  74. GRB 060403: Refined analysis of the Swift-BAT burst
  75. GRB060403: Swift XRT refined position
  76. Konus-Wind observation of the recent SGR 1900+14 activity. Will
  77. GRB 060403: Swift detection of a burst
  78. HETE trigger H4044: RTT150 optical observations
  79. GRB060331: Swift/UVOT upper limits
  80. H4044, a Repeat Outburst From The Source of H4043 (="GRB060331")
  81. Swift XRT observations of the HETE transient H4043
  82. HETE Trigger 4043: ROTSE-III Optical Limits
  83. Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE
  84. H4043, an unusual high-energy transient observed by HETE
  85. GRB 060322: LNA optical limit
  86. SGR 1900+14: bright burst detected by Konus-Wind on March 28
  87. INTEGRAL and XMM ToO observations of SGR1900+14
  88. SGR 1900+14: Swift-BAT detection of a cluster of outbursts
  89. SGR 1900+14: Swift-BAT detection of a bright outburst
  90. GRB 060218SN 2006aj: optical observations at Rozhen Observatory
  91. GRB 060323 : WIDGET simultaneous optical observations
  92. GRB 060323: Early optical observation at Xinglong
  93. GRB060218, optical observations
  94. GRB 060322: Confirmation of Swift XRT afterglow
  95. GRB 060211A: optical observation
  96. GRB060323: optical limit
  97. GRB060211B: optical observation
  98. SGR 1900+14: CORRECTION to GCN 4923
  99. SGR 1900+14: Refined Swift-BAT analysis of the renewed activity
  100. SGR 1900+14: Swift detection of renewed activity

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