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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 060507: Swift/UVOT Upper Limits
  2. GRB 060507: Swift XRT Team Refined Analysis
  3. GRB 060507: MDM Optical Upper Limit
  4. GRB060507: Swift XRT position
  5. GRB 060507: Swift detection of a burst
  6. GRB 060429: Suzaku WAM observation
  7. GRB060505: Swift/UVOT Observations
  8. GRB 060505: Swift XRT Team Refined Analysis
  9. GRB060425: new MASTER survey method
  10. GRB 060306: Further Analysis of SOAR and APO NIR Observations
  11. GRB 060505: Swift XRT afterglow canditate position
  12. GRB 060502b: Second epoch Gemini observations
  13. GRB 060505: Swift-BAT detection of a weak burst
  14. GRB 060428B: spectroscopy
  15. GRB 060502B: optical observations
  16. GRB 060502B: AROMA refined photometric calibration
  17. GRB 060502B MDM Follow-up Observation
  18. GRB 060502b: Gemini imaging and spectroscopy
  19. GRB060502A, optical observation
  20. GRB 060502B: Swift/UVOT upper limits
  21. GRB 060502A: Swift/UVOT source detection
  22. GRB 060429: Refined IPN error box and Konus-Wind spectrum
  23. GRB 060502B: MDM Optical Observation
  24. GRB 060502B: AROMA optical observations
  25. GRB 060502B: Refined analysis of the Swift-BAT short burst
  26. GRB060502B: Swift XRT Team refined analysis
  27. Short GRB 060502B: Tautenburg Observation
  28. GRB 060427B Milagro GeV/TeV Observations
  29. GRB 060502A: TTT Observations
  30. GRB060502B: correction to XRT position
  31. GRB 060501: P60 Observations and Candidate Retraction
  32. GRB 060502B: Xinglong optical observation
  33. GRB 060502B: MASTER optical observations
  34. GRB 060502B: Swift detection of a short burst
  35. GRB060502: Swift-XRT refined analysis
  36. GRB 060502: Swift-BAT refined analysis
  37. GRB060502: Gemini spectroscopy
  38. GRB 060502: APO Spectroscopic Observations
  39. GRB060501: Swift UVOT followup observations
  40. GRB060502: Super-LOTIS Observations
  41. GRB 060502: P60 Afterglow Confirmation
  42. GRB 060502: Swift detection of a burst with an optical counterpart
  43. GRB 060501: MDM Observations
  44. GRB060501: Super-LOTIS observations
  45. GRB060501: P60 imaging and afterglow candidate
  46. GRB 060501: Refined analysis of the Swift-BAT burst
  47. GRB060501: Swift XRT position
  48. GRB 060501: ROTSE-III Optical Limits
  49. GRB 060501: Swift detection of a burst
  50. IPN triangulation of GRB060429 (short/hard)
  51. Konus-Wind observation of GRB 060427B
  52. GRB060428B - SDSS Pre-Burst Observations
  53. GRB060428B: optical observation
  54. GRB060428B: possible detection of an optical counterpart by Swift/UVOT.
  55. GRB 060428B: MDM Observations
  56. GRB 060428A: PROMPT Observations
  57. GRB 060427B: MASTER optical observations
  58. GRB060428B: Swift XRT Team refined analysis
  59. GRB 060427B: IPN localization of a short hard burst
  60. GRB 060428B: Refined analysis of the Swift-BAT burst
  61. GRB 060428B: Xinglong I-band limit
  62. GRB 060428B: KAIT observations
  63. GRB060425:MASTER optical limit
  64. GRB 051117A: Bright host galaxy not confirmed
  65. GRB060428A: Swift/UVOT observations.
  66. GRB060428B, optical observation
  67. GRB 060428A: Refined analysis of the Swift-BAT burst
  68. GRB 060428b : Kiso R-band limit
  69. GRB060427:MASTER optical limit
  70. GRB 060428b: Optical afterglow candidate
  71. GRB060428A: Swift XRT Team refined analysis
  72. GRB 060428B: Swift detection of a burst
  73. GRB 060427: NIR observations
  74. GRB060427: Xinglong optical Observations
  75. GRB 060428: Swift detection of a burst
  76. GRB 060427: NOT observations
  77. GRB 060427: Swift/UVOT upper limits.
  78. GRB 060427: Refined analysis of the Swift-BAT burst
  79. GRB060427: Swift XRT Team refined analysis
  80. GRB060418: Swift XRT Team Further Refined Analysis
  81. GRB060425:MASTER survey observations
  82. GRB 060427, optical observation
  83. GRB 060427: Swift detection of a burst
  84. GRB 060425: IPN localization and KW spectrum of a short, hard burst
  85. An interactive program for GRB pseudo-redshift computations
  86. GRB060424: optical afterglow detection
  87. GRB060418: Further Analysis of MIKE Spectroscopy
  88. GRB 060424: Refined analysis of the Swift-BAT burst
  89. GRB 060424: Swift detection of a burst
  90. GRB 060421: TTT Observations
  91. OT 060420: Likely Not a New Cosmic Transient
  92. No OT 060420 in MASCOT images
  93. Swift-BAT detection of Mrk 421
  94. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  95. GRB060421: Swift/UVOT observations
  96. GRB 060421: Swift-BAT Refined Analysis
  97. GRB 060421: Swift-XRT refined analysis
  98. GRB 060418: prediction of t_break
  99. GRB060418: optical observations
  100. Konus-Wind observation of GRB 060418

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