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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-XRT refined analysis
  2. SWIFT J195509.6+261406 / GRB 070610: SWIFT continued observations
  3. GRB 070612B: Swift/UVOT upper limits
  4. GRB 070612B: FRAM limit
  5. GRB070612B: P60 Observations
  6. GRB 070612B: KAIT limits
  7. GRB 070612A: SARA detection of possible OT
  8. GRB 070612B: Swift XRT position from downlink data
  9. GRB 070610: TAROT Calern observatory optical observations
  10. GRB 070610: MITSuME OAO optical upper limit
  11. GRB 070612B: Swift detection of a burst
  12. GRB070612 - SDSS Pre-Burst Observations
  13. GRB 070612: Swift detection of a burst
  14. GRB 070610: OPTIMA-Burst detection of continued strong flaring activity
  15. GRB 070610: SARA upper limit
  16. GRB 070610: Swift-XRT refined analysis
  17. GRB 070610: TLS RRM sees flaring behaviour - Galactic transient?
  18. GRB 070611: Swift/UVOT Observations
  19. GRB 070611: Swift-XRT refined analysis
  20. GRB 070611, Swift-BAT refined analysis
  21. GRB 070610: Optical observations from OSN
  22. GRB 070610: Watcher Observations
  23. GRB 070611: VLT redshift
  24. GRB 060121 : pseudo-z = 1.9 ('intermediate-duration' burst)
  25. GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
  26. GRB 070611; Swift-XRT position
  27. GRB 070611: ROTSE-III Optical Limits
  28. GRB 070611: Swift detection of a burst
  29. GRB 070610: Swift-UVOT Upper Limits
  30. GRB 070610: OPTIMA-Burst high-time-resolution optical observations
  31. GRB 070610, Swift-BAT refined analysis
  32. GRB 070610; Swift-XRT position
  33. GRB 070610: Swift detection of a burst
  34. GRB 070412: TAROT Calern observatory optical observations
  35. GRB 070411: TAROT Calern observatory optical observations
  36. GRB 070419A, deep LBT photometry and possible supernova detection
  37. GRB070520B: optical observations
  38. GRB070520: optical observation
  39. GRB070518: optical observation
  40. GRB070521: optical observation
  41. Swift/UVOT refined analysis of GRB070531
  42. GRB 070531: NOT nIR observations
  43. GRB 070531: Swift-BAT refined analysis
  44. GRB 070531: I-band observations from IAC80
  45. GRB 070531: Swift-XRT position
  46. GRB 070531: Liverpool Telescope Optical Observations
  47. GRB 070531: Swift detection of a burst
  48. GRB 070529: SARA upper limit
  49. Swift/UVOT refined analysis of GRB070529
  50. GRB 070529: MARGE Observations
  51. GRB 070529: Optical aterglow from MIRO
  52. GRB 070529: Gemini Redshift
  53. GRB 070529: Swift-XRT refined analysis
  54. GRB 070529, Swift-BAT refined analysis
  55. GRB 070529: Xinglong TNT Optical Upper Limit
  56. GRB 070529: Swift detection of a burst with an optical aterglow
  57. GRB 070412: Deep Keck imaging
  58. Swift Triggers 280447, 280450 and 280451 are invalid
  59. Swift trigger 280447 is probably a Galactic transient
  60. GRB 070518, deep LBT photometry
  61. GRB 070518: MARGE Observations
  62. GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
  63. Konus-Wind observation of GRB 070521
  64. GRB 070518: optical observation
  65. GRB070521: Second Epoch Gemini Imaging
  66. GRB070521: NIR observations
  67. GRB070520B: NIR observations
  68. GRB 070521: Swift/UVOT Upper Limits
  69. GRB 070521, optical observation
  70. GRB 070521: Swift-XRT refined analysis
  71. GRB 070521: Keck imaging
  72. GRB070521: Gemini Observations
  73. GROND upper limits of GRB 070521
  74. GRB 070521 Milagro GeV/TeV Observations
  75. GRB 070520B: SARA upper limit
  76. GRB 070520A: SARA upper limit
  77. GRB 070521: SARA upper limit
  78. GRB 070521: Subaru observations and possible host detection
  79. GRB070518: Optical/NIR observation
  80. GRB 070520B: Swift/UVOT Upper Limits
  81. GRB 070520A: Subaru Observations
  82. GRB 070521, Swift-BAT refined analysis
  83. GRB 070520A: Swift UVOT Upper Limits
  84. GRB 070520B: Swift-XRT refined analysis
  85. GRB 070521: optical limit by Pi of the Sky
  86. GRB070521: P200 Observations
  87. GRB070521 : Faulkes Telescope North Observations
  88. GRB 070521: TAROT La Silla observatory optical observations
  89. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  90. GRB070521 - SDSS Pre-Burst Observations
  91. GRB 070521: Swift detection of a burst
  92. GRB 070520A: MITSuME Akeno optical upper limits
  93. GRB 070520B, Swift-BAT refined analysis
  94. GRB 070520A, Swift-BAT refined analysis
  95. GRB 070520A: Swift-XRT refined analysis
  96. GRB 070518: TNG observations
  97. GRB 070520B: Swift detection of a burst
  98. GRB 070520: Xinglong EST optical Upper Limit
  99. GRB 070520: Swift detection of a burst
  100. VLA observation of GRB 070518

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