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

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