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

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