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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"

25559 results found.

  1. GRB 090427B: Fermi GBM detection
  2. GRB 090426C: Fermi GBM detection
  3. GRB 090426B: Fermi GBM detection/observation
  4. GRB 090429B: Swift XRT refined analysis
  5. GRB 090429A: Enhanced Swift-XRT position
  6. Konus-Wind observation of very bright GRB 090427
  7. GRB 090428B: Fermi GBM detection
  8. GRB 090428: Fermi GBM detection
  9. GRB 090418A BVRcIc field calibration
  10. GRB 090429B: Swift-BAT refined analysis
  11. GRB 090429A: Swift-BAT refined analysis
  12. GRB 090429B: Enhanced Swift-XRT position
  13. GRB090429B: Gemini-N infrared IR candidate
  14. GRB 090426: YNAO-GMG observations
  15. GRB 090429B: GROND Observations
  16. GRB 090429B: Swift detection of a burst
  17. GRB 090429: Swift detection of a burst
  18. GRB 090423: pseudo burst at z=1 and its relation to GRB 080913
  19. GRB 090426: R-band limit
  20. GRB 090424: Continued R-band monitoring
  21. GRB 090423: millimeter detection
  22. GRB 090425: Fermi GBM detection
  23. GRB 090424: Suzaku WAM observation of the prompt emission
  24. GRB 090426: VLT spectroscopy
  25. GRB090426 Swift/UVOT observations
  26. GRB 090426: Swift-BAT refined analysis
  27. GRB 090426: Swift-XRT refined analysis
  28. Detection of bright radio afterglow of GRB 090424 with the VLA
  29. GRB 090426: Enhanced Swift-XRT position
  30. GRB 090426: inspection of SDSS images
  31. GRB 090426: Swift detection of a burst with an optical counterpart
  32. GRB090424: R-band detection (37.5 hrs post-burst), jet break?
  33. GRB 090424: MASTER-Net prompt optical limit
  34. GRB 090424: WHT ISIS spectroscopy
  35. VLA radio observation of high-z GRB 090423
  36. GRB090424: BVRI/R-band detection after 15 hrs burst
  37. GRB 090424 : Lulin 1m telescope optical observations
  38. GRB090423: Y-band limit
  39. GRB 090424 Gemini-South Redshift
  40. GRB 090423: Y-band field calibration update/correction
  41. GRB 090423: Swift/BAT spectral lag results
  42. GRB 090424 : TAOS optical detection
  43. GRB 090424 optical observations
  44. GRB 090424: Swift-XRT refined analysis
  45. GRB 090424: Optical observations from 1.23m CAHA
  46. GRB 090423: energetic, luminosity and jet break
  47. Swift/UVOT observations of GRB 090424
  48. GRB 090424: Enhanced Swift-XRT position
  49. GRB 090424: Swift-BAT refined analysis
  50. GRB 090424: Fermi GBM Observation
  51. GRB 090423: Fermi GBM observation
  52. GRB 090422: Fermi GBM observation
  53. GRB 090423: Ep,i - Eiso correlation
  54. GRB 090424: SDSS Galaxy at the Swift position
  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: Near infrared observation at Okayama Observatory
  60. GRB 090423: GROND detection and preliminary photo-z
  61. GRB 090423: Swift-XRT refined analysis
  62. GRB090418A Rc-band photometry
  63. GRB090423 - Swift/UVOT upper limits.
  64. GRB 090423: NIR photometry and evidence for spectral break
  65. GRB 090422: Swift-XRT refined analysis
  66. GRB 090423: UKIRT data further analysis
  67. GRB 090423: Enhanced Swift-XRT position
  68. GRB 090423: Swift-BAT refined analysis
  69. GRB 090422: Swift/UVOT Upper Limits
  70. GRB 090423: Swift detection of a burst
  71. GRB 090418A: Konus-Wind and Swift/BAT joint spectral analysis
  72. GRB 090422: Swift-BAT refined analysis
  73. GRB 090422: Enhanced Swift-XRT position
  74. GRB 090418B: Suzaku WAM observation of the prompt emission
  75. GRB 090422: Swift detection of a burst
  76. GRB 090418C: Fermi GBM Detection
  77. GRB 090419: Swift-XRT refined analysis
  78. Konus-Wind observation of GRB 090418B
  79. GRB 090419: Swift-BAT refined analysis
  80. VLA radio detection of GRB 090418
  81. VLA radio upper limit on GRB 090417B
  82. GRB 090419: Enhanced Swift-XRT position
  83. GRB 090418: Swift XRT refined analysis
  84. GRB 090419: Swift detection of a burst
  85. VLA observations of short burst GRB 090417A
  86. GRB 090418B: Detection of a bright burst from Swift-BAT slew data
  87. GRB 090418: Swift-BAT refined analysis
  88. GRB 090417B: Swift-XRT refined analysis
  89. GRB 090418: Enhanced Swift-XRT position
  90. GRB 090418: Swift detection of a burst with optical afterglow
  91. GRB 090411B: Suzaku WAM observation of the prompt emission
  92. GRB 090411A: Suzaku WAM observation of the prompt emission
  93. GRB 090417B: Subaru NIR Observations
  94. GRB 090417B: Liverpool Telescope observations
  95. GRB090417B: Xinglong TNT optical upper limit
  96. GRB 090417B: Swift-BAT refined analysis
  97. GRB 090417A: Swift-BAT refined analysis
  98. GRB 090417A: nearby galaxy redshift
  99. GRB 090417B: Swift detection of a burst
  100. GRB 090417: Swift detection of a short burst

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