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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 070612B: Swift detection of a burst
  2. GRB070612 - SDSS Pre-Burst Observations
  3. GRB 070612: Swift detection of a burst
  4. GRB 070610: OPTIMA-Burst detection of continued strong flaring activity
  5. GRB 070610: SARA upper limit
  6. GRB 070610: Swift-XRT refined analysis
  7. GRB 070610: TLS RRM sees flaring behaviour - Galactic transient?
  8. GRB 070611: Swift/UVOT Observations
  9. GRB 070611: Swift-XRT refined analysis
  10. GRB 070611, Swift-BAT refined analysis
  11. GRB 070610: Optical observations from OSN
  12. GRB 070610: Watcher Observations
  13. GRB 070611: VLT redshift
  14. GRB 060121 : pseudo-z = 1.9 ('intermediate-duration' burst)
  15. GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
  16. GRB 070611; Swift-XRT position
  17. GRB 070611: ROTSE-III Optical Limits
  18. GRB 070611: Swift detection of a burst
  19. GRB 070610: Swift-UVOT Upper Limits
  20. GRB 070610: OPTIMA-Burst high-time-resolution optical observations
  21. GRB 070610, Swift-BAT refined analysis
  22. GRB 070610; Swift-XRT position
  23. GRB 070610: Swift detection of a burst
  24. GRB 070412: TAROT Calern observatory optical observations
  25. GRB 070411: TAROT Calern observatory optical observations
  26. GRB 070419A, deep LBT photometry and possible supernova detection
  27. GRB070520B: optical observations
  28. GRB070520: optical observation
  29. GRB070518: optical observation
  30. GRB070521: optical observation
  31. Swift/UVOT refined analysis of GRB070531
  32. GRB 070531: NOT nIR observations
  33. GRB 070531: Swift-BAT refined analysis
  34. GRB 070531: I-band observations from IAC80
  35. GRB 070531: Swift-XRT position
  36. GRB 070531: Liverpool Telescope Optical Observations
  37. GRB 070531: Swift detection of a burst
  38. GRB 070529: SARA upper limit
  39. Swift/UVOT refined analysis of GRB070529
  40. GRB 070529: MARGE Observations
  41. GRB 070529: Optical aterglow from MIRO
  42. GRB 070529: Gemini Redshift
  43. GRB 070529: Swift-XRT refined analysis
  44. GRB 070529, Swift-BAT refined analysis
  45. GRB 070529: Xinglong TNT Optical Upper Limit
  46. GRB 070529: Swift detection of a burst with an optical aterglow
  47. GRB 070412: Deep Keck imaging
  48. Swift Triggers 280447, 280450 and 280451 are invalid
  49. Swift trigger 280447 is probably a Galactic transient
  50. GRB 070518, deep LBT photometry
  51. GRB 070518: MARGE Observations
  52. GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
  53. Konus-Wind observation of GRB 070521
  54. GRB 070518: optical observation
  55. GRB070521: Second Epoch Gemini Imaging
  56. GRB070521: NIR observations
  57. GRB070520B: NIR observations
  58. GRB 070521: Swift/UVOT Upper Limits
  59. GRB 070521, optical observation
  60. GRB 070521: Swift-XRT refined analysis
  61. GRB 070521: Keck imaging
  62. GRB070521: Gemini Observations
  63. GROND upper limits of GRB 070521
  64. GRB 070521 Milagro GeV/TeV Observations
  65. GRB 070520B: SARA upper limit
  66. GRB 070520A: SARA upper limit
  67. GRB 070521: SARA upper limit
  68. GRB 070521: Subaru observations and possible host detection
  69. GRB070518: Optical/NIR observation
  70. GRB 070520B: Swift/UVOT Upper Limits
  71. GRB 070520A: Subaru Observations
  72. GRB 070521, Swift-BAT refined analysis
  73. GRB 070520A: Swift UVOT Upper Limits
  74. GRB 070520B: Swift-XRT refined analysis
  75. GRB 070521: optical limit by Pi of the Sky
  76. GRB070521: P200 Observations
  77. GRB070521 : Faulkes Telescope North Observations
  78. GRB 070521: TAROT La Silla observatory optical observations
  79. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  80. GRB070521 - SDSS Pre-Burst Observations
  81. GRB 070521: Swift detection of a burst
  82. GRB 070520A: MITSuME Akeno optical upper limits
  83. GRB 070520B, Swift-BAT refined analysis
  84. GRB 070520A, Swift-BAT refined analysis
  85. GRB 070520A: Swift-XRT refined analysis
  86. GRB 070518: TNG observations
  87. GRB 070520B: Swift detection of a burst
  88. GRB 070520: Xinglong EST optical Upper Limit
  89. GRB 070520: Swift detection of a burst
  90. VLA observation of GRB 070518
  91. GRB 070518: Swift-XRT refined analysis
  92. GRB 070517: Gemini optical imaging
  93. GRB070518: UVOT refined analysis
  94. GRB070518: OSN observation
  95. GRB 070518, Swift-BAT refined analysis
  96. GRB 070518: OT confirmed form Xinglong TNT observation
  97. GRB 070518: Swift detection of a burst with optical afterglow
  98. GRB070517: Swift-XRT Refined Analysis
  99. GRB 070517, Swift-BAT refined analysis
  100. GRB 070517: Optical search

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