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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 070520B, Swift-BAT refined analysis
  2. GRB 070520A, Swift-BAT refined analysis
  3. GRB 070520A: Swift-XRT refined analysis
  4. GRB 070518: TNG observations
  5. GRB 070520B: Swift detection of a burst
  6. GRB 070520: Xinglong EST optical Upper Limit
  7. GRB 070520: Swift detection of a burst
  8. VLA observation of GRB 070518
  9. GRB 070518: Swift-XRT refined analysis
  10. GRB 070517: Gemini optical imaging
  11. GRB070518: UVOT refined analysis
  12. GRB070518: OSN observation
  13. GRB 070518, Swift-BAT refined analysis
  14. GRB 070518: OT confirmed form Xinglong TNT observation
  15. GRB 070518: Swift detection of a burst with optical afterglow
  16. GRB070517: Swift-XRT Refined Analysis
  17. GRB 070517, Swift-BAT refined analysis
  18. GRB 070517: Optical search
  19. GRB 070517: Swift detection of a burst
  20. GRB 070509: objects inside XRT error circle
  21. GRB 070512: pseudo-z ~ 1.39 from prompt emission spectrum
  22. GRB 070512: IPN localization and Konus spectrum of a bright burst
  23. GRB070419A: optical observations
  24. GRB 070419A, Deep LBT photometry
  25. GRB 070508: pseudo-z from 4 different spectral analyses
  26. GRB 070509: Swift/UVOT Upper Limits
  27. Konus-Wind and Konus-A observation of GRB 070508
  28. Swift-BAT trigger 278987 is not a GRB
  29. GRB 070510: Swift detection of a possible burst
  30. GRB070509: Swift-XRT Refined Analysis
  31. RHESSI Spectrum of GRB070508
  32. GRB 070508: OA fading and tentative redshift
  33. GRB 070509, Swift-BAT refined analysis
  34. GRB 070508: Suzaku/WAM observation of the prompt emission
  35. GRB 070509: REM observations
  36. GRB 070509: Swift detection of a burst
  37. GRB 070509: ROTSE-III Optical Limits
  38. GRB070508: Swift/UVOT Observations
  39. GRB 070508, SMARTS optical afterglow observation
  40. GRB 070508, Swift-BAT refined analysis
  41. GRB 070508: Multicolor optical observations and possible redshift limit
  42. GRB 070508: Swift-XRT refined analysis
  43. GRB 070508: Optical observation limiting magnitude
  44. GRB 070508: Optical afterglow detection
  45. GRB 070508: REM observations
  46. GRB 070508: TAROT La Silla observatory optical observations
  47. GRB 070508: Swift detection of an intense burst with an optical counterpart
  48. GRB070412: MAGIC telescope GeV observation
  49. Swift-BAT trigger 278809 is not a GRB
  50. GRB 070507: Swift detection of a possible cosmic ray shower event or a possible burst
  51. GRB 070506: VLT redshift
  52. GRB070506: Swift/UVOT Observations
  53. GRB070506: Swift XRT refined analysis
  54. GRB 070506, Swift-BAT Refined Analysis
  55. GRB 070506: Swift detection of a burst with optical afterglow
  56. GRB 070412, deep LBT imaging
  57. GRB 070429A: Swift XRT further analysis
  58. GRB070429B: VLT observations
  59. GRB 070429A: optical observations
  60. GRB070429B: position correction
  61. GRB 070309: Swift-XRT afterglow confirmation
  62. GRB070429B: possible host galaxy detection
  63. VLA observation of GRB 070429B
  64. Swift/UVOT observations of GRB070429B
  65. GRB 070429B, Swift-BAT refined analysis
  66. Swift/UVOT observations of GRB070429A
  67. GRB 070429A: Swift XRT refined analysis
  68. GRB 070429A, Swift-BAT refined analysis
  69. GRB 070429A: optical and NIR observations
  70. GRB 070429B: Swift XRT refined analysis
  71. GRB 070429B: ROTSE-III Optical Limits
  72. GRB 070429B: Swift detection of a short burst
  73. GRB 070429: What's the temperature?
  74. GRB 070429: ROTSE-III Optical Limits
  75. GRB 070429: Swift detection of a burst
  76. GRB 070427, Swift-BAT Refined Analysis
  77. LT monitoring of GRB070412
  78. GRB 070427: Swift detection of a burst
  79. GRB 070411, further deep LBT photometry
  80. GRB 070411: Late-time Keck imaging
  81. GRB 070411 : Planned XMM-Newton observation
  82. GRB070419B: Suzaku WAM observation of the prompt emission
  83. GRB 070420, SMARTS optical/IR afterglow observations
  84. GRB 070411, deep LBT photometry
  85. GRB 070420: pseudo-z~1.56 from spectral parameters of the prompt
  86. Konus-Wind observation of GRB 070420
  87. GRB 070411: break in the optical light curve
  88. GRB 070420 Swift-BAT Refined Analysis
  89. GRB070419A: Kuiper Optical detection
  90. GRB070419a: Swift UVOT observations
  91. GRB 070419A: MARGE Observations
  92. GRB 070420: optical rebrightening observed at Mt. John
  93. GRB 070420: Swift XRT refined analysis
  94. GRB070420: Swift UVOT continuing observations
  95. GRB 070411: BART early limit
  96. GRB 070420: Faulkes Telescope South Observations
  97. GBR 070419A: Swift/XRT refined analysis
  98. GRB 070420: TAROT La Silla observatory optical observations
  99. GRB 070420: NIR and optical afterglow confirmed
  100. GRB 070420: Swift detection of a burst with optical afterglow

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