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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 060428B: Xinglong I-band limit
  2. GRB 060428B: KAIT observations
  3. GRB060425:MASTER optical limit
  4. GRB 051117A: Bright host galaxy not confirmed
  5. GRB060428A: Swift/UVOT observations.
  6. GRB060428B, optical observation
  7. GRB 060428A: Refined analysis of the Swift-BAT burst
  8. GRB 060428b : Kiso R-band limit
  9. GRB060427:MASTER optical limit
  10. GRB 060428b: Optical afterglow candidate
  11. GRB060428A: Swift XRT Team refined analysis
  12. GRB 060428B: Swift detection of a burst
  13. GRB 060427: NIR observations
  14. GRB060427: Xinglong optical Observations
  15. GRB 060428: Swift detection of a burst
  16. GRB 060427: NOT observations
  17. GRB 060427: Swift/UVOT upper limits.
  18. GRB 060427: Refined analysis of the Swift-BAT burst
  19. GRB060427: Swift XRT Team refined analysis
  20. GRB060418: Swift XRT Team Further Refined Analysis
  21. GRB060425:MASTER survey observations
  22. GRB 060427, optical observation
  23. GRB 060427: Swift detection of a burst
  24. GRB 060425: IPN localization and KW spectrum of a short, hard burst
  25. An interactive program for GRB pseudo-redshift computations
  26. GRB060424: optical afterglow detection
  27. GRB060418: Further Analysis of MIKE Spectroscopy
  28. GRB 060424: Refined analysis of the Swift-BAT burst
  29. GRB 060424: Swift detection of a burst
  30. GRB 060421: TTT Observations
  31. OT 060420: Likely Not a New Cosmic Transient
  32. No OT 060420 in MASCOT images
  33. Swift-BAT detection of Mrk 421
  34. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  35. GRB060421: Swift/UVOT observations
  36. GRB 060421: Swift-BAT Refined Analysis
  37. GRB 060421: Swift-XRT refined analysis
  38. GRB 060418: prediction of t_break
  39. GRB060418: optical observations
  40. Konus-Wind observation of GRB 060418
  41. GRB(?)060421:MASTER optical limit
  42. GRB(?)060421 : XRT position
  43. Possible GRB060421: BART limits
  44. GRB(?) 060421: Swift detection of a burst
  45. Erratum of GCN 4983 for GRB 060418 IR follow-up
  46. GRB 060418 : IR afterglow observations
  47. GRB 060418 : Lulin Optical follow-up
  48. GRB 060418: JHKs PAIRITEL Observations of Afterglow
  49. GRB 060418: Radio Observations
  50. GRB060418, BVRcIc field calibration
  51. GRB060418: Swift/UVOT Observations
  52. GRB060418: Optical Observations
  53. GRB 060418: FRAM early afterglow observation
  54. GRB 060418: Refined Analysis of the Swift-BAT burst
  55. VLT/UVES observations of GRB060418
  56. GRB060418: Swift XRT Team Refined Analysis
  57. GRB 060418, SMARTS continuing afterglow observations
  58. GRB 060418: PROMPT Detections
  59. GRB 060418, SMARTS optical/IR afterglow observations
  60. GRB060418: Magellan/MIKE Spectroscopic Redshift
  61. GRB060418 : LT optical afterglow observation
  62. GRB 060418: REM candidate afterglow
  63. GRB 060418: Swift detection of a burst with bright x-ray and optical afterglow
  64. SGR 1900+14: Refined analysis of the Swift-BAT outburst
  65. GRB060413: Swift/UVOT upper limits
  66. GRB 060413: REM NIR Observations
  67. SGR 1900+14: Swift detection of an outburst
  68. GRB 060413: Refined analysis of the Swift-BAT burst
  69. GRB 060413: Watcher UBVR observations
  70. GRB 060413: XRT refined analysis
  71. GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data
  72. GRB 060413: Swift detection of a burst
  73. GRB060403: optical observations
  74. GRB 060403 Optical observations
  75. GRB 060403: MITSuME optical observation
  76. GRB060403: Optical Limit
  77. GRB060403: XRT refined analysis
  78. GRB 060403: Swift/UVOT upper limits
  79. HETE Triggers H4043 and H4044 Not Due to New Cosmic Source
  80. SGR 1900+14: BAT observations
  81. GRB 060403: Refined analysis of the Swift-BAT burst
  82. GRB060403: Swift XRT refined position
  83. Konus-Wind observation of the recent SGR 1900+14 activity. Will
  84. GRB 060403: Swift detection of a burst
  85. HETE trigger H4044: RTT150 optical observations
  86. GRB060331: Swift/UVOT upper limits
  87. H4044, a Repeat Outburst From The Source of H4043 (="GRB060331")
  88. Swift XRT observations of the HETE transient H4043
  89. HETE Trigger 4043: ROTSE-III Optical Limits
  90. Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE
  91. H4043, an unusual high-energy transient observed by HETE
  92. GRB 060322: LNA optical limit
  93. SGR 1900+14: bright burst detected by Konus-Wind on March 28
  94. INTEGRAL and XMM ToO observations of SGR1900+14
  95. SGR 1900+14: Swift-BAT detection of a cluster of outbursts
  96. SGR 1900+14: Swift-BAT detection of a bright outburst
  97. GRB 060218SN 2006aj: optical observations at Rozhen Observatory
  98. GRB 060323 : WIDGET simultaneous optical observations
  99. GRB 060323: Early optical observation at Xinglong
  100. GRB060218, optical observations

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