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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').
  1. GRB 070610; Swift-XRT position
  2. GRB 070610: Swift detection of a burst
  3. GRB 070412: TAROT Calern observatory optical observations
  4. GRB 070411: TAROT Calern observatory optical observations
  5. GRB 070419A, deep LBT photometry and possible supernova detection
  6. GRB070520B: optical observations
  7. GRB070520: optical observation
  8. GRB070518: optical observation
  9. GRB070521: optical observation
  10. Swift/UVOT refined analysis of GRB070531
  11. GRB 070531: NOT nIR observations
  12. GRB 070531: Swift-BAT refined analysis
  13. GRB 070531: I-band observations from IAC80
  14. GRB 070531: Swift-XRT position
  15. GRB 070531: Liverpool Telescope Optical Observations
  16. GRB 070531: Swift detection of a burst
  17. GRB 070529: SARA upper limit
  18. Swift/UVOT refined analysis of GRB070529
  19. GRB 070529: MARGE Observations
  20. GRB 070529: Optical aterglow from MIRO
  21. GRB 070529: Gemini Redshift
  22. GRB 070529: Swift-XRT refined analysis
  23. GRB 070529, Swift-BAT refined analysis
  24. GRB 070529: Xinglong TNT Optical Upper Limit
  25. GRB 070529: Swift detection of a burst with an optical aterglow
  26. GRB 070412: Deep Keck imaging
  27. Swift Triggers 280447, 280450 and 280451 are invalid
  28. Swift trigger 280447 is probably a Galactic transient
  29. GRB 070518, deep LBT photometry
  30. GRB 070518: MARGE Observations
  31. GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
  32. Konus-Wind observation of GRB 070521
  33. GRB 070518: optical observation
  34. GRB070521: Second Epoch Gemini Imaging
  35. GRB070521: NIR observations
  36. GRB070520B: NIR observations
  37. GRB 070521: Swift/UVOT Upper Limits
  38. GRB 070521, optical observation
  39. GRB 070521: Swift-XRT refined analysis
  40. GRB 070521: Keck imaging
  41. GRB070521: Gemini Observations
  42. GROND upper limits of GRB 070521
  43. GRB 070521 Milagro GeV/TeV Observations
  44. GRB 070520B: SARA upper limit
  45. GRB 070520A: SARA upper limit
  46. GRB 070521: SARA upper limit
  47. GRB 070521: Subaru observations and possible host detection
  48. GRB070518: Optical/NIR observation
  49. GRB 070520B: Swift/UVOT Upper Limits
  50. GRB 070520A: Subaru Observations
  51. GRB 070521, Swift-BAT refined analysis
  52. GRB 070520A: Swift UVOT Upper Limits
  53. GRB 070520B: Swift-XRT refined analysis
  54. GRB 070521: optical limit by Pi of the Sky
  55. GRB070521: P200 Observations
  56. GRB070521 : Faulkes Telescope North Observations
  57. GRB 070521: TAROT La Silla observatory optical observations
  58. GRB070521: Bright SDSS Galaxy Near XRT Error Circle
  59. GRB070521 - SDSS Pre-Burst Observations
  60. GRB 070521: Swift detection of a burst
  61. GRB 070520A: MITSuME Akeno optical upper limits
  62. GRB 070520B, Swift-BAT refined analysis
  63. GRB 070520A, Swift-BAT refined analysis
  64. GRB 070520A: Swift-XRT refined analysis
  65. GRB 070518: TNG observations
  66. GRB 070520B: Swift detection of a burst
  67. GRB 070520: Xinglong EST optical Upper Limit
  68. GRB 070520: Swift detection of a burst
  69. VLA observation of GRB 070518
  70. GRB 070518: Swift-XRT refined analysis
  71. GRB 070517: Gemini optical imaging
  72. GRB070518: UVOT refined analysis
  73. GRB070518: OSN observation
  74. GRB 070518, Swift-BAT refined analysis
  75. GRB 070518: OT confirmed form Xinglong TNT observation
  76. GRB 070518: Swift detection of a burst with optical afterglow
  77. GRB070517: Swift-XRT Refined Analysis
  78. GRB 070517, Swift-BAT refined analysis
  79. GRB 070517: Optical search
  80. GRB 070517: Swift detection of a burst
  81. GRB 070509: objects inside XRT error circle
  82. GRB 070512: pseudo-z ~ 1.39 from prompt emission spectrum
  83. GRB 070512: IPN localization and Konus spectrum of a bright burst
  84. GRB070419A: optical observations
  85. GRB 070419A, Deep LBT photometry
  86. GRB 070508: pseudo-z from 4 different spectral analyses
  87. GRB 070509: Swift/UVOT Upper Limits
  88. Konus-Wind and Konus-A observation of GRB 070508
  89. Swift-BAT trigger 278987 is not a GRB
  90. GRB 070510: Swift detection of a possible burst
  91. GRB070509: Swift-XRT Refined Analysis
  92. RHESSI Spectrum of GRB070508
  93. GRB 070508: OA fading and tentative redshift
  94. GRB 070509, Swift-BAT refined analysis
  95. GRB 070508: Suzaku/WAM observation of the prompt emission
  96. GRB 070509: REM observations
  97. GRB 070509: Swift detection of a burst
  98. GRB 070509: ROTSE-III Optical Limits
  99. GRB070508: Swift/UVOT Observations
  100. GRB 070508, SMARTS optical afterglow observation

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