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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 060424: Swift detection of a burst
  2. GRB 060421: TTT Observations
  3. OT 060420: Likely Not a New Cosmic Transient
  4. No OT 060420 in MASCOT images
  5. Swift-BAT detection of Mrk 421
  6. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  7. GRB060421: Swift/UVOT observations
  8. GRB 060421: Swift-BAT Refined Analysis
  9. GRB 060421: Swift-XRT refined analysis
  10. GRB 060418: prediction of t_break
  11. GRB060418: optical observations
  12. Konus-Wind observation of GRB 060418
  13. GRB(?)060421:MASTER optical limit
  14. GRB(?)060421 : XRT position
  15. Possible GRB060421: BART limits
  16. GRB(?) 060421: Swift detection of a burst
  17. Erratum of GCN 4983 for GRB 060418 IR follow-up
  18. GRB 060418 : IR afterglow observations
  19. GRB 060418 : Lulin Optical follow-up
  20. GRB 060418: JHKs PAIRITEL Observations of Afterglow
  21. GRB 060418: Radio Observations
  22. GRB060418, BVRcIc field calibration
  23. GRB060418: Swift/UVOT Observations
  24. GRB060418: Optical Observations
  25. GRB 060418: FRAM early afterglow observation
  26. GRB 060418: Refined Analysis of the Swift-BAT burst
  27. VLT/UVES observations of GRB060418
  28. GRB060418: Swift XRT Team Refined Analysis
  29. GRB 060418, SMARTS continuing afterglow observations
  30. GRB 060418: PROMPT Detections
  31. GRB 060418, SMARTS optical/IR afterglow observations
  32. GRB060418: Magellan/MIKE Spectroscopic Redshift
  33. GRB060418 : LT optical afterglow observation
  34. GRB 060418: REM candidate afterglow
  35. GRB 060418: Swift detection of a burst with bright x-ray and optical afterglow
  36. SGR 1900+14: Refined analysis of the Swift-BAT outburst
  37. GRB060413: Swift/UVOT upper limits
  38. GRB 060413: REM NIR Observations
  39. SGR 1900+14: Swift detection of an outburst
  40. GRB 060413: Refined analysis of the Swift-BAT burst
  41. GRB 060413: Watcher UBVR observations
  42. GRB 060413: XRT refined analysis
  43. GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data
  44. GRB 060413: Swift detection of a burst
  45. GRB060403: optical observations
  46. GRB 060403 Optical observations
  47. GRB 060403: MITSuME optical observation
  48. GRB060403: Optical Limit
  49. GRB060403: XRT refined analysis
  50. GRB 060403: Swift/UVOT upper limits
  51. HETE Triggers H4043 and H4044 Not Due to New Cosmic Source
  52. SGR 1900+14: BAT observations
  53. GRB 060403: Refined analysis of the Swift-BAT burst
  54. GRB060403: Swift XRT refined position
  55. Konus-Wind observation of the recent SGR 1900+14 activity. Will
  56. GRB 060403: Swift detection of a burst
  57. HETE trigger H4044: RTT150 optical observations
  58. GRB060331: Swift/UVOT upper limits
  59. H4044, a Repeat Outburst From The Source of H4043 (="GRB060331")
  60. Swift XRT observations of the HETE transient H4043
  61. HETE Trigger 4043: ROTSE-III Optical Limits
  62. Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE
  63. H4043, an unusual high-energy transient observed by HETE
  64. GRB 060322: LNA optical limit
  65. SGR 1900+14: bright burst detected by Konus-Wind on March 28
  66. INTEGRAL and XMM ToO observations of SGR1900+14
  67. SGR 1900+14: Swift-BAT detection of a cluster of outbursts
  68. SGR 1900+14: Swift-BAT detection of a bright outburst
  69. GRB 060218SN 2006aj: optical observations at Rozhen Observatory
  70. GRB 060323 : WIDGET simultaneous optical observations
  71. GRB 060323: Early optical observation at Xinglong
  72. GRB060218, optical observations
  73. GRB 060322: Confirmation of Swift XRT afterglow
  74. GRB 060211A: optical observation
  75. GRB060323: optical limit
  76. GRB060211B: optical observation
  77. SGR 1900+14: CORRECTION to GCN 4923
  78. SGR 1900+14: Refined Swift-BAT analysis of the renewed activity
  79. SGR 1900+14: Swift detection of renewed activity
  80. GRB060323: NOT optical observations
  81. GRB 060322: IAC80 optical observations
  82. GRB 060322: Swift XRT afterglow candidate
  83. GRB060323: P60 Observations
  84. GRB 060323: Swift/UVOT Observations
  85. GRB 060323: optical afterglow confirmed
  86. GRB060323: NOT observations
  87. GRB 060323: Optical Observations
  88. GRB 060323: Tautenburg OT candidate retraction
  89. GRB 060323: Refined analysis of the Swift-BAT burst
  90. GRB 060323: optical observations at TNG
  91. GRB 060323: Swift XRT refined analysis
  92. GRB 060323: BVRI observations at Tautenburg, aftreglow candidate
  93. GRB 060323: Swift/XRT position
  94. GRB 060322: Refined analysis of the Swift-BAT burst
  95. GRB060323, optical observation
  96. GRB060323 - SDSS Pre-Burst Observations
  97. GRB 060323: Swift detection of a burst with a possible optical afterglow
  98. GRB 060322: Swift-BAT detection of a 200-sec burst
  99. GRB060219: optical observation
  100. GRB060206: optical observation

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