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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. IPN triangulation of very bright GRB 090427
  2. GRB 090426: R-band limit
  3. GRB 090424: Continued R-band monitoring
  4. GRB 090423: CARMA mm observations
  5. GRB 090423: millimeter detection
  6. GRB 090426: Swift/BAT spectral lag results
  7. GRB 090425: Fermi GBM detection
  8. GRB 090424: Suzaku WAM observation of the prompt emission
  9. GRB 090426: VLT spectroscopy
  10. GRB 090426: GROND Observations of the Optical/NIR Afterglow
  11. GRB 090426: Near infrared observation with ISLE at OAO
  12. GRB 090426: Okayama MITSuME optical observation
  13. GRB090426 Swift/UVOT observations
  14. GRB 090426 Keck LRIS redshift
  15. GRB 090426: Swift-BAT refined analysis
  16. GRB 090426: Swift-XRT refined analysis
  17. GRB 090423: GROND second epoch imaging and refined SED
  18. Detection of bright radio afterglow of GRB 090424 with the VLA
  19. GRB 090426: Enhanced Swift-XRT position
  20. GRB090426: Observation for Optical counterpart from MIRO
  21. GRB 090426, RIMOTS optical upper limits
  22. GRB 090426: inspection of SDSS images
  23. GRB 090426: TNT confimation of optical counterpart
  24. GRB 090426: Swift detection of a burst with an optical counterpart
  25. GRB090424: R-band detection (37.5 hrs post-burst), jet break?
  26. GRB 090424: MASTER-Net prompt optical limit
  27. GRB 090423: Fermi GBM observation (correction of isotropic equivalent energy)
  28. GRB 090424: WHT ISIS spectroscopy
  29. VLA radio observation of high-z GRB 090423
  30. GRB090424: BVRI/R-band detection after 15 hrs burst
  31. GRB 090424 : Lulin 1m telescope optical observations
  32. GRB 090424: THO optical observations
  33. GRB 090424: GROND Observations of the Optical/NIR Afterglow
  34. GRB090423: Y-band limit
  35. GRB 090424 Gemini-South Redshift
  36. GRB 090423: Y-band field calibration update/correction
  37. GRB 090423: Swift/BAT spectral lag results
  38. GRB 090424 : TAOS optical detection
  39. GRB 090424 optical observations
  40. GRB 090424: Liverpool Telescope observations
  41. GRB 090424: Swift-XRT refined analysis
  42. GRB 090424: Optical observations from 1.23m CAHA
  43. GRB 090423: energetic, luminosity and jet break
  44. Swift/UVOT observations of GRB 090424
  45. GRB 090424: MASTER-Net prompt optical observations
  46. GRB 090424: Enhanced Swift-XRT position
  47. GRB 090424: Swift-BAT refined analysis
  48. GRB 090424: Fermi GBM Observation
  49. GRB 090423: Fermi GBM observation
  50. GRB 090422: Fermi GBM observation
  51. GRB 090423: Ep,i - Eiso correlation
  52. GRB 090424: SDSS Galaxy at the Swift position
  53. GRB 090424: TNT optical observations
  54. GRB 090424: ROTSE-III Confimation of Optical Counterpart
  55. GRB 090424: Swift detection of a burst with an optical counterpart
  56. GRB 090423: Refined TNG analysis
  57. GRB090423: Y-band field calibration
  58. GRB 090423 limiting magnitudes
  59. GRB 090423: VLT/ISAAC spectroscopy
  60. GRB 090423: Near infrared observation at Okayama Observatory
  61. GRB 090423: Deep z-band upper limit and confirmation of photo-z
  62. GRB 090423: TNG Amici spectrum
  63. GRB 090423: GROND detection and preliminary photo-z
  64. GRB 090423: NOT z-band limit
  65. GRB 090423: Correction to NIR photometry
  66. GRB 090423: Swift-XRT refined analysis
  67. GRB090418A Rc-band photometry
  68. GRB090423 - Swift/UVOT upper limits.
  69. GRB 090423: NIR photometry and evidence for spectral break
  70. GRB 090422: Swift-XRT refined analysis
  71. GRB090423, RIMOTS optical upper limits
  72. GRB 090423: UKIRT data further analysis
  73. GRB 090423: Enhanced Swift-XRT position
  74. GRB 090423: Swift-BAT refined analysis
  75. GRB 090422: Swift/UVOT Upper Limits
  76. GRB 090423: UKIRT K-band observations
  77. GRB 090423: P60 Observations
  78. GRB 090423: Faulkes Telescope South observations
  79. GRB 090418A: R and I band observation
  80. GRB 090423: Swift detection of a burst
  81. GRB 090422: Liverpool Telescope possible candidate
  82. GRB 090418A: Konus-Wind and Swift/BAT joint spectral analysis
  83. GRB 090422: Swift-BAT refined analysis
  84. GRB 090422: Enhanced Swift-XRT position
  85. GRB 090410: Erratum in GCN 9189
  86. GRB 090408A: Erratum in GCN 9188
  87. GRB 090418B: RTT150 optical observations
  88. GRB 090418A: RTT150 optical observations
  89. GRB 080410: GAO 150cm telescope Optical Observation
  90. GRB 080408A: GAO 150cm telescope Optical Observation
  91. GRB 090422: Liverpool Telescope observations
  92. GRB 090418B: Suzaku WAM observation of the prompt emission
  93. GRB 090422: Swift detection of a burst
  94. GRB 090418C: Fermi GBM Detection
  95. GRB 090418A: Swift/UVOT Detection of the Neighbouring Galaxy
  96. Swift-BAT trigger 349718 is not a burst
  97. GRB 090418B: GRAS002 observatios
  98. GRB 090417B: Optical observation
  99. GRB 090418A: optical observations
  100. GRB 090418B: GROND observations

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