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

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