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

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