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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. GRB090426 Swift/UVOT observations
  2. GRB 090426 Keck LRIS redshift
  3. GRB 090426: Swift-BAT refined analysis
  4. GRB 090426: Swift-XRT refined analysis
  5. GRB 090423: GROND second epoch imaging and refined SED
  6. Detection of bright radio afterglow of GRB 090424 with the VLA
  7. GRB 090426: Enhanced Swift-XRT position
  8. GRB090426: Observation for Optical counterpart from MIRO
  9. GRB 090426, RIMOTS optical upper limits
  10. GRB 090426: inspection of SDSS images
  11. GRB 090426: TNT confimation of optical counterpart
  12. GRB 090426: Swift detection of a burst with an optical counterpart
  13. GRB090424: R-band detection (37.5 hrs post-burst), jet break?
  14. GRB 090424: MASTER-Net prompt optical limit
  15. GRB 090423: Fermi GBM observation (correction of isotropic equivalent energy)
  16. GRB 090424: WHT ISIS spectroscopy
  17. VLA radio observation of high-z GRB 090423
  18. GRB090424: BVRI/R-band detection after 15 hrs burst
  19. GRB 090424 : Lulin 1m telescope optical observations
  20. GRB 090424: THO optical observations
  21. GRB 090424: GROND Observations of the Optical/NIR Afterglow
  22. GRB090423: Y-band limit
  23. GRB 090424 Gemini-South Redshift
  24. GRB 090423: Y-band field calibration update/correction
  25. GRB 090423: Swift/BAT spectral lag results
  26. GRB 090424 : TAOS optical detection
  27. GRB 090424 optical observations
  28. GRB 090424: Liverpool Telescope observations
  29. GRB 090424: Swift-XRT refined analysis
  30. GRB 090424: Optical observations from 1.23m CAHA
  31. GRB 090423: energetic, luminosity and jet break
  32. Swift/UVOT observations of GRB 090424
  33. GRB 090424: MASTER-Net prompt optical observations
  34. GRB 090424: Enhanced Swift-XRT position
  35. GRB 090424: Swift-BAT refined analysis
  36. GRB 090424: Fermi GBM Observation
  37. GRB 090423: Fermi GBM observation
  38. GRB 090422: Fermi GBM observation
  39. GRB 090423: Ep,i - Eiso correlation
  40. GRB 090424: SDSS Galaxy at the Swift position
  41. GRB 090424: TNT optical observations
  42. GRB 090424: ROTSE-III Confimation of Optical Counterpart
  43. GRB 090424: Swift detection of a burst with an optical counterpart
  44. GRB 090423: Refined TNG analysis
  45. GRB090423: Y-band field calibration
  46. GRB 090423 limiting magnitudes
  47. GRB 090423: VLT/ISAAC spectroscopy
  48. GRB 090423: Near infrared observation at Okayama Observatory
  49. GRB 090423: Deep z-band upper limit and confirmation of photo-z
  50. GRB 090423: TNG Amici spectrum
  51. GRB 090423: GROND detection and preliminary photo-z
  52. GRB 090423: NOT z-band limit
  53. GRB 090423: Correction to NIR photometry
  54. GRB 090423: Swift-XRT refined analysis
  55. GRB090418A Rc-band photometry
  56. GRB090423 - Swift/UVOT upper limits.
  57. GRB 090423: NIR photometry and evidence for spectral break
  58. GRB 090422: Swift-XRT refined analysis
  59. GRB090423, RIMOTS optical upper limits
  60. GRB 090423: UKIRT data further analysis
  61. GRB 090423: Enhanced Swift-XRT position
  62. GRB 090423: Swift-BAT refined analysis
  63. GRB 090422: Swift/UVOT Upper Limits
  64. GRB 090423: UKIRT K-band observations
  65. GRB 090423: P60 Observations
  66. GRB 090423: Faulkes Telescope South observations
  67. GRB 090418A: R and I band observation
  68. GRB 090423: Swift detection of a burst
  69. GRB 090422: Liverpool Telescope possible candidate
  70. GRB 090418A: Konus-Wind and Swift/BAT joint spectral analysis
  71. GRB 090422: Swift-BAT refined analysis
  72. GRB 090422: Enhanced Swift-XRT position
  73. GRB 090410: Erratum in GCN 9189
  74. GRB 090408A: Erratum in GCN 9188
  75. GRB 090418B: RTT150 optical observations
  76. GRB 090418A: RTT150 optical observations
  77. GRB 080410: GAO 150cm telescope Optical Observation
  78. GRB 080408A: GAO 150cm telescope Optical Observation
  79. GRB 090422: Liverpool Telescope observations
  80. GRB 090418B: Suzaku WAM observation of the prompt emission
  81. GRB 090422: Swift detection of a burst
  82. GRB 090418C: Fermi GBM Detection
  83. GRB 090418A: Swift/UVOT Detection of the Neighbouring Galaxy
  84. Swift-BAT trigger 349718 is not a burst
  85. GRB 090418B: GRAS002 observatios
  86. GRB 090417B: Optical observation
  87. GRB 090418A: optical observations
  88. GRB 090418B: GROND observations
  89. GRB 090419: Swift/UVOT Observations
  90. GRB 090418B: Faulkes Telescope North observations
  91. GRB 090418A: Swift/UVOT Observations
  92. GRB 090417B: Swift/UVOT Upper Limits
  93. GRB 090417B Correction to the BAT refined analysis position
  94. GRB 090419: Swift-XRT refined analysis
  95. Konus-Wind observation of GRB 090418B
  96. GRB 090418: Erratum in GCN 9168
  97. GRB 090419: GROND detection of afterglow candidate
  98. GRB 090418: Optical observations with MITSuME Okayama and Ishigaki 1m telescope
  99. GRB 090419: Swift-BAT refined analysis
  100. VLA radio detection of GRB 090418

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