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

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