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

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