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

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