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

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