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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. GRB 090429B: Gemini-N further nIR observations
  2. GRB 090424: YNAO-GMG observations
  3. GRB 090429A: Swift-XRT refined analysis
  4. GRB 090429A: GROND upper limits
  5. GRB 090427C: Fermi GBM detection
  6. GRB 090427B: Fermi GBM detection
  7. GRB 090426C: Fermi GBM detection
  8. GRB 090426B: Fermi GBM detection/observation
  9. GRB 090429B: Swift XRT refined analysis
  10. GRB 090429A: Enhanced Swift-XRT position
  11. Konus-Wind observation of very bright GRB 090427
  12. GRB 090428B: Fermi GBM detection
  13. GRB 090428: Fermi GBM detection
  14. GRB 090418A BVRcIc field calibration
  15. GRB 090426: GAO 150cm telescope Optical Observation
  16. GRB 090429B: RIMOTS optical upper limits
  17. GRB 090429B: Swift-BAT refined analysis
  18. GRB 090429A: Swift-BAT refined analysis
  19. GRB 090429B: Enhanced Swift-XRT position
  20. GRB 090429A - Correction to XRT position
  21. GRB090429B: Gemini-N infrared IR candidate
  22. GRB 090426: YNAO-GMG observations
  23. GRB 090429B: VLT upper limits
  24. GRB 090429B: GROND Observations
  25. GRB 090429B: Super-LOTIS early observations
  26. GRB 090429B: Swift detection of a burst
  27. GRB 090429: Swift detection of a burst
  28. GRB 090423: pseudo burst at z=1 and its relation to GRB 080913
  29. GRB 090424 : Multiband Optical observation from Nainital
  30. IPN triangulation of very bright GRB 090427
  31. GRB 090426: R-band limit
  32. GRB 090424: Continued R-band monitoring
  33. GRB 090423: CARMA mm observations
  34. GRB 090423: millimeter detection
  35. GRB 090426: Swift/BAT spectral lag results
  36. GRB 090425: Fermi GBM detection
  37. GRB 090424: Suzaku WAM observation of the prompt emission
  38. GRB 090426: VLT spectroscopy
  39. GRB 090426: GROND Observations of the Optical/NIR Afterglow
  40. GRB 090426: Near infrared observation with ISLE at OAO
  41. GRB 090426: Okayama MITSuME optical observation
  42. GRB090426 Swift/UVOT observations
  43. GRB 090426 Keck LRIS redshift
  44. GRB 090426: Swift-BAT refined analysis
  45. GRB 090426: Swift-XRT refined analysis
  46. GRB 090423: GROND second epoch imaging and refined SED
  47. Detection of bright radio afterglow of GRB 090424 with the VLA
  48. GRB 090426: Enhanced Swift-XRT position
  49. GRB090426: Observation for Optical counterpart from MIRO
  50. GRB 090426, RIMOTS optical upper limits
  51. GRB 090426: inspection of SDSS images
  52. GRB 090426: TNT confimation of optical counterpart
  53. GRB 090426: Swift detection of a burst with an optical counterpart
  54. GRB090424: R-band detection (37.5 hrs post-burst), jet break?
  55. GRB 090424: MASTER-Net prompt optical limit
  56. GRB 090423: Fermi GBM observation (correction of isotropic equivalent energy)
  57. GRB 090424: WHT ISIS spectroscopy
  58. VLA radio observation of high-z GRB 090423
  59. GRB090424: BVRI/R-band detection after 15 hrs burst
  60. GRB 090424 : Lulin 1m telescope optical observations
  61. GRB 090424: THO optical observations
  62. GRB 090424: GROND Observations of the Optical/NIR Afterglow
  63. GRB090423: Y-band limit
  64. GRB 090424 Gemini-South Redshift
  65. GRB 090423: Y-band field calibration update/correction
  66. GRB 090423: Swift/BAT spectral lag results
  67. GRB 090424 : TAOS optical detection
  68. GRB 090424 optical observations
  69. GRB 090424: Liverpool Telescope observations
  70. GRB 090424: Swift-XRT refined analysis
  71. GRB 090424: Optical observations from 1.23m CAHA
  72. GRB 090423: energetic, luminosity and jet break
  73. Swift/UVOT observations of GRB 090424
  74. GRB 090424: MASTER-Net prompt optical observations
  75. GRB 090424: Enhanced Swift-XRT position
  76. GRB 090424: Swift-BAT refined analysis
  77. GRB 090424: Fermi GBM Observation
  78. GRB 090423: Fermi GBM observation
  79. GRB 090422: Fermi GBM observation
  80. GRB 090423: Ep,i - Eiso correlation
  81. GRB 090424: SDSS Galaxy at the Swift position
  82. GRB 090424: TNT optical observations
  83. GRB 090424: ROTSE-III Confimation of Optical Counterpart
  84. GRB 090424: Swift detection of a burst with an optical counterpart
  85. GRB 090423: Refined TNG analysis
  86. GRB090423: Y-band field calibration
  87. GRB 090423 limiting magnitudes
  88. GRB 090423: VLT/ISAAC spectroscopy
  89. GRB 090423: Near infrared observation at Okayama Observatory
  90. GRB 090423: Deep z-band upper limit and confirmation of photo-z
  91. GRB 090423: TNG Amici spectrum
  92. GRB 090423: GROND detection and preliminary photo-z
  93. GRB 090423: NOT z-band limit
  94. GRB 090423: Correction to NIR photometry
  95. GRB 090423: Swift-XRT refined analysis
  96. GRB090418A Rc-band photometry
  97. GRB090423 - Swift/UVOT upper limits.
  98. GRB 090423: NIR photometry and evidence for spectral break
  99. GRB 090422: Swift-XRT refined analysis
  100. GRB090423, RIMOTS optical upper limits

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