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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 070610: SARA upper limit
  2. GRB 070610: Swift-XRT refined analysis
  3. GRB 070610: TLS RRM sees flaring behaviour - Galactic transient?
  4. GRB 070611: Swift/UVOT Observations
  5. GRB 070611: Swift-XRT refined analysis
  6. GRB 070611, Swift-BAT refined analysis
  7. GRB 070610: Optical observations from OSN
  8. GRB 070610: Watcher Observations
  9. GRB 070611: VLT redshift
  10. GRB 060121 : pseudo-z = 1.9 ('intermediate-duration' burst)
  11. GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
  12. GRB 070611; Swift-XRT position
  13. GRB 070611: ROTSE-III Optical Limits
  14. GRB 070611: Swift detection of a burst
  15. GRB 070610: Swift-UVOT Upper Limits
  16. GRB 070610: OPTIMA-Burst high-time-resolution optical observations
  17. GRB 070610, Swift-BAT refined analysis
  18. GRB 070610; Swift-XRT position
  19. GRB 070610: Swift detection of a burst
  20. GRB 070412: TAROT Calern observatory optical observations
  21. GRB 070411: TAROT Calern observatory optical observations
  22. GRB 070419A, deep LBT photometry and possible supernova detection
  23. GRB070520B: optical observations
  24. GRB070520: optical observation
  25. GRB070518: optical observation
  26. GRB070521: optical observation
  27. Swift/UVOT refined analysis of GRB070531
  28. GRB 070531: NOT nIR observations
  29. GRB 070531: Swift-BAT refined analysis
  30. GRB 070531: I-band observations from IAC80
  31. GRB 070531: Swift-XRT position
  32. GRB 070531: Liverpool Telescope Optical Observations
  33. GRB 070531: Swift detection of a burst
  34. GRB 070529: SARA upper limit
  35. Swift/UVOT refined analysis of GRB070529
  36. GRB 070529: MARGE Observations
  37. GRB 070529: Optical aterglow from MIRO
  38. GRB 070529: Gemini Redshift
  39. GRB 070529: Swift-XRT refined analysis
  40. GRB 070529, Swift-BAT refined analysis
  41. GRB 070529: Xinglong TNT Optical Upper Limit
  42. GRB 070529: Swift detection of a burst with an optical aterglow
  43. GRB 070412: Deep Keck imaging
  44. Swift Triggers 280447, 280450 and 280451 are invalid
  45. Swift trigger 280447 is probably a Galactic transient
  46. GRB 070518, deep LBT photometry
  47. GRB 070518: MARGE Observations
  48. GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
  49. Konus-Wind observation of GRB 070521
  50. GRB 070518: optical observation
  51. GRB070521: Second Epoch Gemini Imaging
  52. GRB070521: NIR observations
  53. GRB070520B: NIR observations
  54. GRB 070521: Swift/UVOT Upper Limits
  55. GRB 070521, optical observation
  56. GRB 070521: Swift-XRT refined analysis
  57. GRB 070521: Keck imaging
  58. GRB070521: Gemini Observations
  59. GROND upper limits of GRB 070521
  60. GRB 070521 Milagro GeV/TeV Observations
  61. GRB 070520B: SARA upper limit
  62. GRB 070520A: SARA upper limit
  63. GRB 070521: SARA upper limit
  64. GRB 070521: Subaru observations and possible host detection
  65. GRB070518: Optical/NIR observation
  66. GRB 070520B: Swift/UVOT Upper Limits
  67. GRB 070520A: Subaru Observations
  68. GRB 070521, Swift-BAT refined analysis
  69. GRB 070520A: Swift UVOT Upper Limits
  70. GRB 070520B: Swift-XRT refined analysis
  71. GRB 070521: optical limit by Pi of the Sky
  72. GRB070521: P200 Observations
  73. GRB070521 : Faulkes Telescope North Observations
  74. GRB 070521: TAROT La Silla observatory optical observations
  75. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  76. GRB070521 - SDSS Pre-Burst Observations
  77. GRB 070521: Swift detection of a burst
  78. GRB 070520A: MITSuME Akeno optical upper limits
  79. GRB 070520B, Swift-BAT refined analysis
  80. GRB 070520A, Swift-BAT refined analysis
  81. GRB 070520A: Swift-XRT refined analysis
  82. GRB 070518: TNG observations
  83. GRB 070520B: Swift detection of a burst
  84. GRB 070520: Xinglong EST optical Upper Limit
  85. GRB 070520: Swift detection of a burst
  86. VLA observation of GRB 070518
  87. GRB 070518: Swift-XRT refined analysis
  88. GRB 070517: Gemini optical imaging
  89. GRB070518: UVOT refined analysis
  90. GRB070518: OSN observation
  91. GRB 070518, Swift-BAT refined analysis
  92. GRB 070518: OT confirmed form Xinglong TNT observation
  93. GRB 070518: Swift detection of a burst with optical afterglow
  94. GRB070517: Swift-XRT Refined Analysis
  95. GRB 070517, Swift-BAT refined analysis
  96. GRB 070517: Optical search
  97. GRB 070517: Swift detection of a burst
  98. GRB 070509: objects inside XRT error circle
  99. GRB 070512: pseudo-z ~ 1.39 from prompt emission spectrum
  100. GRB 070512: IPN localization and Konus spectrum of a bright burst

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