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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, optical observation
  2. GRB 070521: Swift-XRT refined analysis
  3. GRB 070521: Keck imaging
  4. GRB070521: Gemini Observations
  5. GROND upper limits of GRB 070521
  6. GRB 070521 Milagro GeV/TeV Observations
  7. GRB 070520B: SARA upper limit
  8. GRB 070520A: SARA upper limit
  9. GRB 070521: SARA upper limit
  10. GRB 070521: Subaru observations and possible host detection
  11. GRB070518: Optical/NIR observation
  12. GRB 070520B: Swift/UVOT Upper Limits
  13. GRB 070520A: Subaru Observations
  14. GRB 070521, Swift-BAT refined analysis
  15. GRB 070520A: Swift UVOT Upper Limits
  16. GRB 070520B: Swift-XRT refined analysis
  17. GRB 070521: optical limit by Pi of the Sky
  18. GRB070521: P200 Observations
  19. GRB070521 : Faulkes Telescope North Observations
  20. GRB 070521: TAROT La Silla observatory optical observations
  21. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  22. GRB070521 - SDSS Pre-Burst Observations
  23. GRB 070521: Swift detection of a burst
  24. GRB 070520A: MITSuME Akeno optical upper limits
  25. GRB 070520B, Swift-BAT refined analysis
  26. GRB 070520A, Swift-BAT refined analysis
  27. GRB 070520A: Swift-XRT refined analysis
  28. GRB 070518: TNG observations
  29. GRB 070520B: Swift detection of a burst
  30. GRB 070520: Xinglong EST optical Upper Limit
  31. GRB 070520: Swift detection of a burst
  32. VLA observation of GRB 070518
  33. GRB 070518: Swift-XRT refined analysis
  34. GRB 070517: Gemini optical imaging
  35. GRB070518: UVOT refined analysis
  36. GRB070518: OSN observation
  37. GRB 070518, Swift-BAT refined analysis
  38. GRB 070518: OT confirmed form Xinglong TNT observation
  39. GRB 070518: Swift detection of a burst with optical afterglow
  40. GRB070517: Swift-XRT Refined Analysis
  41. GRB 070517, Swift-BAT refined analysis
  42. GRB 070517: Optical search
  43. GRB 070517: Swift detection of a burst
  44. GRB 070509: objects inside XRT error circle
  45. GRB 070512: pseudo-z ~ 1.39 from prompt emission spectrum
  46. GRB 070512: IPN localization and Konus spectrum of a bright burst
  47. GRB070419A: optical observations
  48. GRB 070419A, Deep LBT photometry
  49. GRB 070508: pseudo-z from 4 different spectral analyses
  50. GRB 070509: Swift/UVOT Upper Limits
  51. Konus-Wind and Konus-A observation of GRB 070508
  52. Swift-BAT trigger 278987 is not a GRB
  53. GRB 070510: Swift detection of a possible burst
  54. GRB070509: Swift-XRT Refined Analysis
  55. RHESSI Spectrum of GRB070508
  56. GRB 070508: OA fading and tentative redshift
  57. GRB 070509, Swift-BAT refined analysis
  58. GRB 070508: Suzaku/WAM observation of the prompt emission
  59. GRB 070509: REM observations
  60. GRB 070509: Swift detection of a burst
  61. GRB 070509: ROTSE-III Optical Limits
  62. GRB070508: Swift/UVOT Observations
  63. GRB 070508, SMARTS optical afterglow observation
  64. GRB 070508, Swift-BAT refined analysis
  65. GRB 070508: Multicolor optical observations and possible redshift limit
  66. GRB 070508: Swift-XRT refined analysis
  67. GRB 070508: Optical observation limiting magnitude
  68. GRB 070508: Optical afterglow detection
  69. GRB 070508: REM observations
  70. GRB 070508: TAROT La Silla observatory optical observations
  71. GRB 070508: Swift detection of an intense burst with an optical counterpart
  72. GRB070412: MAGIC telescope GeV observation
  73. Swift-BAT trigger 278809 is not a GRB
  74. GRB 070507: Swift detection of a possible cosmic ray shower event or a possible burst
  75. GRB 070506: VLT redshift
  76. GRB070506: Swift/UVOT Observations
  77. GRB070506: Swift XRT refined analysis
  78. GRB 070506, Swift-BAT Refined Analysis
  79. GRB 070506: Swift detection of a burst with optical afterglow
  80. GRB 070412, deep LBT imaging
  81. GRB 070429A: Swift XRT further analysis
  82. GRB070429B: VLT observations
  83. GRB 070429A: optical observations
  84. GRB070429B: position correction
  85. GRB 070309: Swift-XRT afterglow confirmation
  86. GRB070429B: possible host galaxy detection
  87. VLA observation of GRB 070429B
  88. Swift/UVOT observations of GRB070429B
  89. GRB 070429B, Swift-BAT refined analysis
  90. Swift/UVOT observations of GRB070429A
  91. GRB 070429A: Swift XRT refined analysis
  92. GRB 070429A, Swift-BAT refined analysis
  93. GRB 070429A: optical and NIR observations
  94. GRB 070429B: Swift XRT refined analysis
  95. GRB 070429B: ROTSE-III Optical Limits
  96. GRB 070429B: Swift detection of a short burst
  97. GRB 070429: What's the temperature?
  98. GRB 070429: ROTSE-III Optical Limits
  99. GRB 070429: Swift detection of a burst
  100. GRB 070427, Swift-BAT Refined Analysis

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