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

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