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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"

37518 results found.

  1. GRB 150204A: Swift-XRT observations
  2. GRB 150204A: Fermi GBM detection
  3. GRB 150204A: Swift ToO observations
  4. GRB 150204A BAT refined analysis
  5. GRB 150202B: Swift XRT/UVOT observations
  6. GRB 150204A found in ground analysis of Swift-BAT data
  7. GRB 150203A: RAPTOR Limits Beginning at the Gamma-Ray Emitting Interval
  8. GRB 150202A, Swift-BAT refined analysis
  9. GRB 150203A: Swift/UVOT Upper Limits
  10. GRB 150203A: ISON-NM early optical limit
  11. IPN Triangulation of GRB 150202B
  12. GRB 150203A: Swift-XRT refined Analysis
  13. GRB 150202B: Tiled Swift observations
  14. GRB 150203A: MITSuME Okayama upper limits
  15. Swift Trigger 629693: probably not real
  16. Fermi GBM trigger 150202624 is not a GRB
  17. GRB 150202A: Swift/UVOT Upper Limits
  18. GRB 150203A: REM optical and NIR observations
  19. GRB 150202A: Swift-XRT refined Analysis
  20. GRB 150203A: Fermi GBM observation
  21. GRB 150202B: Fermi GBM detection
  22. GRB 150203A: TAROT La Silla observatory optical observations
  23. GRB 150203A: GROND Upper limits
  24. GRB 150202B: Fermi-LAT detection
  25. GRB 150203A: Enhanced Swift-XRT position
  26. GRB 150203A: RATIR Optical and NIR Observations
  27. GRB 150202A: Enhanced Swift-XRT position
  28. GRB 150202A: GROND Upper limits
  29. GRB 150203A: P60 observations
  30. GRB 150203A: KAIT Optical Upper Limit
  31. GRB 150203A: Prompt enhanced Swift-XRT position
  32. GRB 150203A: Swift detection of a burst
  33. GRB 150202A: Swift detection of a burst
  34. GRB 150201A: Swift/UVOT Upper Limits
  35. GRB 150201A, Swift-BAT refined analysis
  36. Konus-Wind observation of GRB 150201A
  37. GRB 150201A: GROND upper limits
  38. GRB 150201A: Swift-XRT refined Analysis
  39. GRB 150201A: Fermi GBM observation
  40. GRB 150201A: Enhanced Swift-XRT position
  41. GRB 150201A: Swift detection of a burst
  42. GRB 150120B: Khureltogot optical observations
  43. GRB 150128A: MASTER OT detction during inspection
  44. GRB 150127B: Fermi GBM detection
  45. Konus-Wind observation of GRB 150127B
  46. GRB 150123A: MASTER inspection
  47. GRB 150120A: 9.8 GHz VLA upper limit
  48. IPN Triangulation of GRB 150127B
  49. IPN Triangulation of GRB 150127A
  50. GRB 150120A: Gemini-N imaging and host redshift
  51. Konus-Wind observation of GRB 150126A reveals its ultra-long nature
  52. GRB 150127A: Fermi-LAT detection
  53. GRB150127A: Fermi GBM Detection
  54. GRB 150126A: Fermi GBM Detection
  55. GRB 150126A: MAXI/GSC afterglow candidate detection
  56. Konus-Wind observation of GRB 150123A
  57. GRB 150120A: possible AMI 15 GHz detection
  58. GRB 150123A: Swift/UVOT observations
  59. GRB 150123A: Swift-XRT observations
  60. GRB 150120B: Mondy optical observations
  61. GRB 150123A Tiled Swift observations
  62. GRB 150123A: MAXI/GSC detection
  63. Konus-Wind observation of GRB 150118B
  64. GRB 150120B: RATIR Optical and NIR Observations
  65. IPN Triangulation of GRB 150118B (long/intense)
  66. GRB 150120A: ISON-NM early optical limit
  67. GRB 150120B: FTN early optical light curve
  68. GRB150120B: Xinglong TNT optical observation
  69. GRB 150120B: Swift/UVOT Upper Limits
  70. GRB 150120B, Optical observations
  71. GRB 150120B: GROND Afterglow Detection
  72. GRB 150120B: Additional P60 observations
  73. GRB 150120A: Swift-XRT refined Analysis
  74. GRB 150101B: Confirmation of a fading optical counterpart
  75. GRB 150120A: KAIT Optical Upper Limit
  76. GRB 150120B: MITSuME Okayama upper limits
  77. GRB 150120B: Swift-BAT refined analysis
  78. GRB 150120A: Swift-BAT refined analysis
  79. GRB 150118C: Fermi GBM Detection
  80. Konus-Wind observation of GRB 150118C
  81. GRB 150101B/Swift J123205.1-105602: TNG NIR follow-up
  82. GRB 150120B: Swift-XRT refined Analysis
  83. IPN triangulation of GRB 150118C (short/hard)
  84. GRB 150120A: Swift/UVOT Upper Limits
  85. GRB 150110B: AMI 15 GHz detection of possible radio counterpart
  86. GRB 150101B/Swift J123205.1-105602, deep VLT observations
  87. GRB 150120B: Enhanced Swift-XRT position
  88. GRB 150120A: Fermi GBM observation
  89. GRB 150101B/Swift J123205.1-105602: XMM-Newton observation
  90. GRB 150120A: Enhanced Swift-XRT position
  91. GRB 150120B: FTN optical afterglow confirmation
  92. GRB 150120B: P60 optical afterglow
  93. GRB 150120B: Swift detection of a burst
  94. GRB 150120A: Gemini-North optical imaging
  95. GRB 150120A: P60 optical observations
  96. GRB 150120A: Prompt enhanced Swift-XRT position
  97. GRB 150120A: Swift detection of a possibly-short burst
  98. GRB 150101B/Swift J123205.1-105602: continued WSRT radio and VLT optical observations
  99. GRB 150118B: Fermi GBM Detection
  100. GRB 150118B: Fermi-LAT detection

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