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

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