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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. GRB090618: Spectrum and photometry from 6.0m BTA
  2. GRB 090618: BOAO V-band Observation
  3. GRB 090621: Swift detection of a burst
  4. GRB 090618: ZTSh optical observations
  5. GRB 090618 : WSRT radio detection
  6. GRB090618, underlying supernova search
  7. GRB090618: OAA-OAUV Optical observations
  8. GRB 090618: Fermi GBM observation
  9. GRB 090618, Swift-BAT refined spectral analysis
  10. VLA radio detection of GRB 090618
  11. GRB 090618 15GHz radio detection
  12. GRB090618 - Continued optical monitoring and light curve break
  13. GRB 090618: Swift-BAT refined analysis
  14. GRB 090618: SARA observations
  15. GRB090618: Swift-XRT team refined analysis
  16. GRB090618: Swift/UVOT bright afterglow detection
  17. GRB 090618: SDSS host detection
  18. Swift XRT observations of GRB 090531A
  19. GRB 090618: AGILE observations
  20. GRB 090617: Fermi GBM detection
  21. GRB 090618: LOAO R-band Observation
  22. GRB 090618: Enhanced Swift-XRT position
  23. GRB 090618 Faulkes Telescope North observations
  24. Optical observations of GRB 090618
  25. GRB 090618: Lick/KAST Spectroscopy
  26. GRB 090618: OA behavior from KAIT
  27. GRB 090618: planned XMM-Newton observation
  28. GRB 090618: ROTSE-III Detection of Optical Counterpart
  29. GRB 090618: KAIT optical afterglow
  30. GRB090618: P60 Optical Afterglow
  31. GRB 090618: Swift detection of a bright burst with optical afterglow
  32. GRB 090616: Fermi GBM detection
  33. GRB 090612: Fermi GBM detection
  34. GRB 090610C: Fermi GBM detection
  35. GRB 090610B: Fermi GBM detection
  36. GRB 090610: Fermi GBM detection
  37. SGR 0418+5729 Fermi/GBM Detection of Pulsations
  38. GRB 090602: Suzaku WAM observation of the prompt emission
  39. GRB 090424: WSRT Radio Observations
  40. GRB 090423: WSRT Radio Observations
  41. RXTE Discovery of Pulsations from SGR 0418+5729
  42. GRB 090531B: Fermi GBM detection
  43. Konus-RF observation of SGR burst 090605A
  44. Discovery of a new soft gamma repeater source, SGR 0418+5729
  45. GRB 090608: Fermi GBM detection
  46. GRB 090606: Fermi GBM detection
  47. GRB 090607: XRT Team Refined Analysis
  48. GRB 090607: Swift/UVOT Upper Limits
  49. GRB 090607: Swift-BAT refined analysis of the SHB
  50. GRB 090607: GRAS001 optical observations
  51. GRB 090607: Faulkes Telescope North observations
  52. GRB 090607: Swift detection of a burst
  53. Ignore GCN/Swift-BAT Lightcurve Notices for trigger 353567
  54. GRB 090530B: Suzaku WAM observation of the prompt emission
  55. GRB 090530: Further NOT optical observations
  56. GRB 090530: RTT150 Optical Observation
  57. GRB 090602: Fermi GBM detection
  58. GRB 090529A: RTT150 Optical Observations
  59. GMRT observation of GRB 090424 afterglow
  60. GRB 090528: Suzaku WAM observation of the prompt emission
  61. GRB090529: Further NOT optical observations
  62. GRB 090531b, SMARTS optical/IR observations
  63. GRB 090531B: GROND observation
  64. GRB 090528B: Suzaku WAM observation of the prompt emission
  65. GRB 090530: Early RAPTOR Optical Observations
  66. GRB090529B: ROVOR Upper Limits
  67. GRB 090531A: SARA upper limit
  68. GRB 090531B: Swift/BAT spectral lag results
  69. GRB 090529C: Fermi GBM detection
  70. GRB 090529B: Fermi GBM detection
  71. GRB 090530B: Fermi GBM detection
  72. Corrections to GRB 090531B Swift/UVOT Upper Limits
  73. GRB 090531B, RIMOTS optical upper limits
  74. GRB 090531B: Swift/UVOT Upper Limits
  75. GRB 090528B: MASTER-II Kourovka optical limit
  76. GRB 090529: MITSuME optical observation
  77. GRB 090530: GRT Optical Observation
  78. GRB 090531B: Swift-BAT refined analysis
  79. Initial Swift/UVOT observations of GRB 090531B
  80. GRB 090531B: Swift-XRT candidate afterglow position
  81. GRB 090531B: ROTSE-III Optical Limits
  82. GRB 090531B: Swift detection of a burst
  83. GRB 090531: Swift-BAT refined analysis
  84. GRB090530: R-band Observation
  85. GRB 090530: break in light curve
  86. GRB 090529: VLT spectroscopic redshift
  87. GRB 090531: GROND upper limits
  88. GRB 090531: P60 Observations
  89. GRB 090531: Swift detection of a burst
  90. GRB 090529: NOT optical observations
  91. GRB 090530: NOT optical observations
  92. GRB090530: Swift XRT refined analysis
  93. GRB090530: Swift/UVOT afterglow detection
  94. GRB 090529: Swift-XRT refined analysis
  95. GRB 090529: OSN optical observations
  96. GRB 090528B: Fermi GBM detection
  97. GRB 090528: Fermi GBM detection
  98. GRB 090530: Enhanced Swift-XRT position
  99. Strong radio emission from SN 2007bg one year after the explosion - detection of spreading, off-axis GRB jet?
  100. GRB 090530: Swift-BAT refined analysis

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