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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 070521: Swift/UVOT Upper Limits
  2. GRB 070521, optical observation
  3. GRB 070521: Swift-XRT refined analysis
  4. GRB 070521: Keck imaging
  5. GRB070521: Gemini Observations
  6. GROND upper limits of GRB 070521
  7. GRB 070521 Milagro GeV/TeV Observations
  8. GRB 070520B: SARA upper limit
  9. GRB 070520A: SARA upper limit
  10. GRB 070521: SARA upper limit
  11. GRB 070521: Subaru observations and possible host detection
  12. GRB070518: Optical/NIR observation
  13. GRB 070520B: Swift/UVOT Upper Limits
  14. GRB 070520A: Subaru Observations
  15. GRB 070521, Swift-BAT refined analysis
  16. GRB 070520A: Swift UVOT Upper Limits
  17. GRB 070520B: Swift-XRT refined analysis
  18. GRB 070521: optical limit by Pi of the Sky
  19. GRB070521: P200 Observations
  20. GRB070521 : Faulkes Telescope North Observations
  21. GRB 070521: TAROT La Silla observatory optical observations
  22. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  23. GRB070521 - SDSS Pre-Burst Observations
  24. GRB 070521: Swift detection of a burst
  25. GRB 070520A: MITSuME Akeno optical upper limits
  26. GRB 070520B, Swift-BAT refined analysis
  27. GRB 070520A, Swift-BAT refined analysis
  28. GRB 070520A: Swift-XRT refined analysis
  29. GRB 070518: TNG observations
  30. GRB 070520B: Swift detection of a burst
  31. GRB 070520: Xinglong EST optical Upper Limit
  32. GRB 070520: Swift detection of a burst
  33. VLA observation of GRB 070518
  34. GRB 070518: Swift-XRT refined analysis
  35. GRB 070517: Gemini optical imaging
  36. GRB070518: UVOT refined analysis
  37. GRB070518: OSN observation
  38. GRB 070518, Swift-BAT refined analysis
  39. GRB 070518: OT confirmed form Xinglong TNT observation
  40. GRB 070518: Swift detection of a burst with optical afterglow
  41. GRB070517: Swift-XRT Refined Analysis
  42. GRB 070517, Swift-BAT refined analysis
  43. GRB 070517: Optical search
  44. GRB 070517: Swift detection of a burst
  45. GRB 070509: objects inside XRT error circle
  46. GRB 070512: pseudo-z ~ 1.39 from prompt emission spectrum
  47. GRB 070512: IPN localization and Konus spectrum of a bright burst
  48. GRB070419A: optical observations
  49. GRB 070419A, Deep LBT photometry
  50. GRB 070508: pseudo-z from 4 different spectral analyses
  51. GRB 070509: Swift/UVOT Upper Limits
  52. Konus-Wind and Konus-A observation of GRB 070508
  53. Swift-BAT trigger 278987 is not a GRB
  54. GRB 070510: Swift detection of a possible burst
  55. GRB070509: Swift-XRT Refined Analysis
  56. RHESSI Spectrum of GRB070508
  57. GRB 070508: OA fading and tentative redshift
  58. GRB 070509, Swift-BAT refined analysis
  59. GRB 070508: Suzaku/WAM observation of the prompt emission
  60. GRB 070509: REM observations
  61. GRB 070509: Swift detection of a burst
  62. GRB 070509: ROTSE-III Optical Limits
  63. GRB070508: Swift/UVOT Observations
  64. GRB 070508, SMARTS optical afterglow observation
  65. GRB 070508, Swift-BAT refined analysis
  66. GRB 070508: Multicolor optical observations and possible redshift limit
  67. GRB 070508: Swift-XRT refined analysis
  68. GRB 070508: Optical observation limiting magnitude
  69. GRB 070508: Optical afterglow detection
  70. GRB 070508: REM observations
  71. GRB 070508: TAROT La Silla observatory optical observations
  72. GRB 070508: Swift detection of an intense burst with an optical counterpart
  73. GRB070412: MAGIC telescope GeV observation
  74. Swift-BAT trigger 278809 is not a GRB
  75. GRB 070507: Swift detection of a possible cosmic ray shower event or a possible burst
  76. GRB 070506: VLT redshift
  77. GRB070506: Swift/UVOT Observations
  78. GRB070506: Swift XRT refined analysis
  79. GRB 070506, Swift-BAT Refined Analysis
  80. GRB 070506: Swift detection of a burst with optical afterglow
  81. GRB 070412, deep LBT imaging
  82. GRB 070429A: Swift XRT further analysis
  83. GRB070429B: VLT observations
  84. GRB 070429A: optical observations
  85. GRB070429B: position correction
  86. GRB 070309: Swift-XRT afterglow confirmation
  87. GRB070429B: possible host galaxy detection
  88. VLA observation of GRB 070429B
  89. Swift/UVOT observations of GRB070429B
  90. GRB 070429B, Swift-BAT refined analysis
  91. Swift/UVOT observations of GRB070429A
  92. GRB 070429A: Swift XRT refined analysis
  93. GRB 070429A, Swift-BAT refined analysis
  94. GRB 070429A: optical and NIR observations
  95. GRB 070429B: Swift XRT refined analysis
  96. GRB 070429B: ROTSE-III Optical Limits
  97. GRB 070429B: Swift detection of a short burst
  98. GRB 070429: What's the temperature?
  99. GRB 070429: ROTSE-III Optical Limits
  100. GRB 070429: Swift detection of a burst

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