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

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