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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. GRB060418: Further Analysis of MIKE Spectroscopy
  2. GRB 060424: Refined analysis of the Swift-BAT burst
  3. GRB 060424: Swift detection of a burst
  4. GRB 060421: TTT Observations
  5. OT 060420: Likely Not a New Cosmic Transient
  6. No OT 060420 in MASCOT images
  7. Swift-BAT detection of Mrk 421
  8. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  9. GRB060421: Swift/UVOT observations
  10. GRB 060421: Swift-BAT Refined Analysis
  11. GRB 060421: Swift-XRT refined analysis
  12. GRB 060418: prediction of t_break
  13. GRB060418: optical observations
  14. Konus-Wind observation of GRB 060418
  15. GRB(?)060421:MASTER optical limit
  16. GRB(?)060421 : XRT position
  17. Possible GRB060421: BART limits
  18. GRB(?) 060421: Swift detection of a burst
  19. Erratum of GCN 4983 for GRB 060418 IR follow-up
  20. GRB 060418 : IR afterglow observations
  21. GRB 060418 : Lulin Optical follow-up
  22. GRB 060418: JHKs PAIRITEL Observations of Afterglow
  23. GRB 060418: Radio Observations
  24. GRB060418, BVRcIc field calibration
  25. GRB060418: Swift/UVOT Observations
  26. GRB060418: Optical Observations
  27. GRB 060418: FRAM early afterglow observation
  28. GRB 060418: Refined Analysis of the Swift-BAT burst
  29. VLT/UVES observations of GRB060418
  30. GRB060418: Swift XRT Team Refined Analysis
  31. GRB 060418, SMARTS continuing afterglow observations
  32. GRB 060418: PROMPT Detections
  33. GRB 060418, SMARTS optical/IR afterglow observations
  34. GRB060418: Magellan/MIKE Spectroscopic Redshift
  35. GRB060418 : LT optical afterglow observation
  36. GRB 060418: REM candidate afterglow
  37. GRB 060418: Swift detection of a burst with bright x-ray and optical afterglow
  38. SGR 1900+14: Refined analysis of the Swift-BAT outburst
  39. GRB060413: Swift/UVOT upper limits
  40. GRB 060413: REM NIR Observations
  41. SGR 1900+14: Swift detection of an outburst
  42. GRB 060413: Refined analysis of the Swift-BAT burst
  43. GRB 060413: Watcher UBVR observations
  44. GRB 060413: XRT refined analysis
  45. GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data
  46. GRB 060413: Swift detection of a burst
  47. GRB060403: optical observations
  48. GRB 060403 Optical observations
  49. GRB 060403: MITSuME optical observation
  50. GRB060403: Optical Limit
  51. GRB060403: XRT refined analysis
  52. GRB 060403: Swift/UVOT upper limits
  53. HETE Triggers H4043 and H4044 Not Due to New Cosmic Source
  54. SGR 1900+14: BAT observations
  55. GRB 060403: Refined analysis of the Swift-BAT burst
  56. GRB060403: Swift XRT refined position
  57. Konus-Wind observation of the recent SGR 1900+14 activity. Will
  58. GRB 060403: Swift detection of a burst
  59. HETE trigger H4044: RTT150 optical observations
  60. GRB060331: Swift/UVOT upper limits
  61. H4044, a Repeat Outburst From The Source of H4043 (="GRB060331")
  62. Swift XRT observations of the HETE transient H4043
  63. HETE Trigger 4043: ROTSE-III Optical Limits
  64. Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE
  65. H4043, an unusual high-energy transient observed by HETE
  66. GRB 060322: LNA optical limit
  67. SGR 1900+14: bright burst detected by Konus-Wind on March 28
  68. INTEGRAL and XMM ToO observations of SGR1900+14
  69. SGR 1900+14: Swift-BAT detection of a cluster of outbursts
  70. SGR 1900+14: Swift-BAT detection of a bright outburst
  71. GRB 060218SN 2006aj: optical observations at Rozhen Observatory
  72. GRB 060323 : WIDGET simultaneous optical observations
  73. GRB 060323: Early optical observation at Xinglong
  74. GRB060218, optical observations
  75. GRB 060322: Confirmation of Swift XRT afterglow
  76. GRB 060211A: optical observation
  77. GRB060323: optical limit
  78. GRB060211B: optical observation
  79. SGR 1900+14: CORRECTION to GCN 4923
  80. SGR 1900+14: Refined Swift-BAT analysis of the renewed activity
  81. SGR 1900+14: Swift detection of renewed activity
  82. GRB060323: NOT optical observations
  83. GRB 060322: IAC80 optical observations
  84. GRB 060322: Swift XRT afterglow candidate
  85. GRB060323: P60 Observations
  86. GRB 060323: Swift/UVOT Observations
  87. GRB 060323: optical afterglow confirmed
  88. GRB060323: NOT observations
  89. GRB 060323: Optical Observations
  90. GRB 060323: Tautenburg OT candidate retraction
  91. GRB 060323: Refined analysis of the Swift-BAT burst
  92. GRB 060323: optical observations at TNG
  93. GRB 060323: Swift XRT refined analysis
  94. GRB 060323: BVRI observations at Tautenburg, aftreglow candidate
  95. GRB 060323: Swift/XRT position
  96. GRB 060322: Refined analysis of the Swift-BAT burst
  97. GRB060323, optical observation
  98. GRB060323 - SDSS Pre-Burst Observations
  99. GRB 060323: Swift detection of a burst with a possible optical afterglow
  100. GRB 060322: Swift-BAT detection of a 200-sec burst

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