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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 060429: Suzaku WAM observation
  2. GRB060505: Swift/UVOT Observations
  3. GRB 060505: Swift XRT Team Refined Analysis
  4. GRB060425: new MASTER survey method
  5. GRB 060306: Further Analysis of SOAR and APO NIR Observations
  6. GRB 060505: Swift XRT afterglow canditate position
  7. GRB 060502b: Second epoch Gemini observations
  8. GRB 060505: Swift-BAT detection of a weak burst
  9. GRB 060428B: spectroscopy
  10. GRB 060502B: optical observations
  11. GRB 060502B: AROMA refined photometric calibration
  12. GRB 060502B MDM Follow-up Observation
  13. GRB 060502b: Gemini imaging and spectroscopy
  14. GRB060502A, optical observation
  15. GRB 060502B: Swift/UVOT upper limits
  16. GRB 060502A: Swift/UVOT source detection
  17. GRB 060429: Refined IPN error box and Konus-Wind spectrum
  18. GRB 060502B: MDM Optical Observation
  19. GRB 060502B: AROMA optical observations
  20. GRB 060502B: Refined analysis of the Swift-BAT short burst
  21. GRB060502B: Swift XRT Team refined analysis
  22. Short GRB 060502B: Tautenburg Observation
  23. GRB 060427B Milagro GeV/TeV Observations
  24. GRB 060502A: TTT Observations
  25. GRB060502B: correction to XRT position
  26. GRB 060501: P60 Observations and Candidate Retraction
  27. GRB 060502B: Xinglong optical observation
  28. GRB 060502B: MASTER optical observations
  29. GRB 060502B: Swift detection of a short burst
  30. GRB060502: Swift-XRT refined analysis
  31. GRB 060502: Swift-BAT refined analysis
  32. GRB060502: Gemini spectroscopy
  33. GRB 060502: APO Spectroscopic Observations
  34. GRB060501: Swift UVOT followup observations
  35. GRB060502: Super-LOTIS Observations
  36. GRB 060502: P60 Afterglow Confirmation
  37. GRB 060502: Swift detection of a burst with an optical counterpart
  38. GRB 060501: MDM Observations
  39. GRB060501: Super-LOTIS observations
  40. GRB060501: P60 imaging and afterglow candidate
  41. GRB 060501: Refined analysis of the Swift-BAT burst
  42. GRB060501: Swift XRT position
  43. GRB 060501: ROTSE-III Optical Limits
  44. GRB 060501: Swift detection of a burst
  45. IPN triangulation of GRB060429 (short/hard)
  46. Konus-Wind observation of GRB 060427B
  47. GRB060428B - SDSS Pre-Burst Observations
  48. GRB060428B: optical observation
  49. GRB060428B: possible detection of an optical counterpart by Swift/UVOT.
  50. GRB 060428B: MDM Observations
  51. GRB 060428A: PROMPT Observations
  52. GRB 060427B: MASTER optical observations
  53. GRB060428B: Swift XRT Team refined analysis
  54. GRB 060427B: IPN localization of a short hard burst
  55. GRB 060428B: Refined analysis of the Swift-BAT burst
  56. GRB 060428B: Xinglong I-band limit
  57. GRB 060428B: KAIT observations
  58. GRB060425:MASTER optical limit
  59. GRB 051117A: Bright host galaxy not confirmed
  60. GRB060428A: Swift/UVOT observations.
  61. GRB060428B, optical observation
  62. GRB 060428A: Refined analysis of the Swift-BAT burst
  63. GRB 060428b : Kiso R-band limit
  64. GRB060427:MASTER optical limit
  65. GRB 060428b: Optical afterglow candidate
  66. GRB060428A: Swift XRT Team refined analysis
  67. GRB 060428B: Swift detection of a burst
  68. GRB 060427: NIR observations
  69. GRB060427: Xinglong optical Observations
  70. GRB 060428: Swift detection of a burst
  71. GRB 060427: NOT observations
  72. GRB 060427: Swift/UVOT upper limits.
  73. GRB 060427: Refined analysis of the Swift-BAT burst
  74. GRB060427: Swift XRT Team refined analysis
  75. GRB060418: Swift XRT Team Further Refined Analysis
  76. GRB060425:MASTER survey observations
  77. GRB 060427, optical observation
  78. GRB 060427: Swift detection of a burst
  79. GRB 060425: IPN localization and KW spectrum of a short, hard burst
  80. An interactive program for GRB pseudo-redshift computations
  81. GRB060424: optical afterglow detection
  82. GRB060418: Further Analysis of MIKE Spectroscopy
  83. GRB 060424: Refined analysis of the Swift-BAT burst
  84. GRB 060424: Swift detection of a burst
  85. GRB 060421: TTT Observations
  86. OT 060420: Likely Not a New Cosmic Transient
  87. No OT 060420 in MASCOT images
  88. Swift-BAT detection of Mrk 421
  89. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  90. GRB060421: Swift/UVOT observations
  91. GRB 060421: Swift-BAT Refined Analysis
  92. GRB 060421: Swift-XRT refined analysis
  93. GRB 060418: prediction of t_break
  94. GRB060418: optical observations
  95. Konus-Wind observation of GRB 060418
  96. GRB(?)060421:MASTER optical limit
  97. GRB(?)060421 : XRT position
  98. Possible GRB060421: BART limits
  99. GRB(?) 060421: Swift detection of a burst
  100. Erratum of GCN 4983 for GRB 060418 IR follow-up

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