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

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