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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: Swift-XRT refined analysis
  2. GRB 070610: TLS RRM sees flaring behaviour - Galactic transient?
  3. GRB 070611: Swift/UVOT Observations
  4. GRB 070611: Swift-XRT refined analysis
  5. GRB 070611, Swift-BAT refined analysis
  6. GRB 070610: Optical observations from OSN
  7. GRB 070610: Watcher Observations
  8. GRB 070611: VLT redshift
  9. GRB 060121 : pseudo-z = 1.9 ('intermediate-duration' burst)
  10. GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
  11. GRB 070611; Swift-XRT position
  12. GRB 070611: ROTSE-III Optical Limits
  13. GRB 070611: Swift detection of a burst
  14. GRB 070610: Swift-UVOT Upper Limits
  15. GRB 070610: OPTIMA-Burst high-time-resolution optical observations
  16. GRB 070610, Swift-BAT refined analysis
  17. GRB 070610; Swift-XRT position
  18. GRB 070610: Swift detection of a burst
  19. GRB 070412: TAROT Calern observatory optical observations
  20. GRB 070411: TAROT Calern observatory optical observations
  21. GRB 070419A, deep LBT photometry and possible supernova detection
  22. GRB070520B: optical observations
  23. GRB070520: optical observation
  24. GRB070518: optical observation
  25. GRB070521: optical observation
  26. Swift/UVOT refined analysis of GRB070531
  27. GRB 070531: NOT nIR observations
  28. GRB 070531: Swift-BAT refined analysis
  29. GRB 070531: I-band observations from IAC80
  30. GRB 070531: Swift-XRT position
  31. GRB 070531: Liverpool Telescope Optical Observations
  32. GRB 070531: Swift detection of a burst
  33. GRB 070529: SARA upper limit
  34. Swift/UVOT refined analysis of GRB070529
  35. GRB 070529: MARGE Observations
  36. GRB 070529: Optical aterglow from MIRO
  37. GRB 070529: Gemini Redshift
  38. GRB 070529: Swift-XRT refined analysis
  39. GRB 070529, Swift-BAT refined analysis
  40. GRB 070529: Xinglong TNT Optical Upper Limit
  41. GRB 070529: Swift detection of a burst with an optical aterglow
  42. GRB 070412: Deep Keck imaging
  43. Swift Triggers 280447, 280450 and 280451 are invalid
  44. Swift trigger 280447 is probably a Galactic transient
  45. GRB 070518, deep LBT photometry
  46. GRB 070518: MARGE Observations
  47. GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
  48. Konus-Wind observation of GRB 070521
  49. GRB 070518: optical observation
  50. GRB070521: Second Epoch Gemini Imaging
  51. GRB070521: NIR observations
  52. GRB070520B: NIR observations
  53. GRB 070521: Swift/UVOT Upper Limits
  54. GRB 070521, optical observation
  55. GRB 070521: Swift-XRT refined analysis
  56. GRB 070521: Keck imaging
  57. GRB070521: Gemini Observations
  58. GROND upper limits of GRB 070521
  59. GRB 070521 Milagro GeV/TeV Observations
  60. GRB 070520B: SARA upper limit
  61. GRB 070520A: SARA upper limit
  62. GRB 070521: SARA upper limit
  63. GRB 070521: Subaru observations and possible host detection
  64. GRB070518: Optical/NIR observation
  65. GRB 070520B: Swift/UVOT Upper Limits
  66. GRB 070520A: Subaru Observations
  67. GRB 070521, Swift-BAT refined analysis
  68. GRB 070520A: Swift UVOT Upper Limits
  69. GRB 070520B: Swift-XRT refined analysis
  70. GRB 070521: optical limit by Pi of the Sky
  71. GRB070521: P200 Observations
  72. GRB070521 : Faulkes Telescope North Observations
  73. GRB 070521: TAROT La Silla observatory optical observations
  74. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  75. GRB070521 - SDSS Pre-Burst Observations
  76. GRB 070521: Swift detection of a burst
  77. GRB 070520A: MITSuME Akeno optical upper limits
  78. GRB 070520B, Swift-BAT refined analysis
  79. GRB 070520A, Swift-BAT refined analysis
  80. GRB 070520A: Swift-XRT refined analysis
  81. GRB 070518: TNG observations
  82. GRB 070520B: Swift detection of a burst
  83. GRB 070520: Xinglong EST optical Upper Limit
  84. GRB 070520: Swift detection of a burst
  85. VLA observation of GRB 070518
  86. GRB 070518: Swift-XRT refined analysis
  87. GRB 070517: Gemini optical imaging
  88. GRB070518: UVOT refined analysis
  89. GRB070518: OSN observation
  90. GRB 070518, Swift-BAT refined analysis
  91. GRB 070518: OT confirmed form Xinglong TNT observation
  92. GRB 070518: Swift detection of a burst with optical afterglow
  93. GRB070517: Swift-XRT Refined Analysis
  94. GRB 070517, Swift-BAT refined analysis
  95. GRB 070517: Optical search
  96. GRB 070517: Swift detection of a burst
  97. GRB 070509: objects inside XRT error circle
  98. GRB 070512: pseudo-z ~ 1.39 from prompt emission spectrum
  99. GRB 070512: IPN localization and Konus spectrum of a bright burst
  100. GRB070419A: optical observations

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