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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. GRB001120: Optical observations
  2. GRB001109, optical observations
  3. GRB001120, optical observations
  4. WSRT 4.8 GHz observations of GRB001109
  5. IPN triangulation of GRB001120
  6. Optical/NIR observations of GRB001109
  7. GRB 001109: deep JHK upper limits
  8. GRB 001109 X-ray afterglow with BeppoSAX
  9. CORRECTION to XMM-Newton observation of GRB001025
  10. GRB001109: Optical observations
  11. GRB001109: BeppoSAX/NFI Observations
  12. GRB001109, R-band optical observations
  13. GRB001109, Radio observations
  14. GRB001109: BeppoSAX refined WFC position
  15. BeppoSAX ALERT: GRB001109
  16. GRB001105 BVRI field photometry correction
  17. GRB001105, BVRI field photometry
  18. GRB 001105, R-band observation
  19. IPN TRIANGULATION OF GRB001105
  20. GRB 001025B, Optical obervations
  21. GRB 991208: HST Imaging of the Host Galaxy
  22. GRB000926: R-image of the host galaxy
  23. GRB 001025B, I-band observations
  24. XMM-Newton observation of GRB001025
  25. GRB001025B, Radio observations
  26. GRB 001025 Optical Observations
  27. GRB 001025A, optical observation
  28. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  29. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  30. IPN triangulation of GRB001025
  31. GRB001007: Optical observations
  32. ASM Localization of GRB 001025
  33. GRB001007, Radio observations
  34. IPN TRIANGULATION OF GRB001020
  35. GRB001019, Optical Observations
  36. GRB 001018, Possible Radio Afterglow
  37. GRB001018, Gamma Ray Observations
  38. IPN TRIANGULATION OF GRB001019
  39. CORRECTION TO PEAK FLUX OF GRB001018
  40. IPN TRIANGULATION OF GRB001018
  41. IPN TRIANGULATION OF GRB 001017
  42. GRB 000926: Improved Absorber Redshift
  43. V,R,I band observations of GRB000926
  44. The Likely Optical/Infrared Afterglow of GRB 001011
  45. HETE positions added to GCN
  46. GRB001011 BeppoSAX/WFC refined position
  47. BeppoSAX ALERT: GRB001011
  48. GRB 001007, BVR-band observations
  49. GRB000926 - Amateur Optical Observations
  50. GRB001007: Optical observations
  51. CONCAM null result on GRB001005
  52. IPN triangulation of GRB001007
  53. GRB 000926 : the host galaxy
  54. HETE-2 Launches Successfully
  55. IPN triangulation of GRB001005
  56. HETE-2 48 hour Launch Delay
  57. GRB 000926 Chandra Observation
  58. IPN triangulation of GRB 001004
  59. Public availability of BeppoSAX data of GRB000926
  60. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  61. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  62. GRB000926 - Optical observations
  63. GRB000926 - Optical observations
  64. GRB 000926, Optical Decay
  65. GRB000911: VLT infrared observation
  66. GRB000926 - Optical observations
  67. GRB000926 - Optical observations
  68. GRB 000926: optical observations
  69. GRB 000926, Optical Observations
  70. GRB000926 - Optical observations
  71. GRB000911: optical VLT observations
  72. GRB000926 K'-band Observation
  73. GRB000926 : increasing optical decay slope
  74. GRB000926 optical observations
  75. GRB000926 - Optical observations
  76. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  77. J and K band observations of GRB 000926
  78. GRB000911 Optical Observations
  79. GRB 000926: Lightcurve Update and Predictions
  80. GRB 000926, optical observation by Oksanen (vsnet-grb)
  81. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  82. GRB000926: Optical observations
  83. CONCAM crude optical limits before and after GRB000926
  84. GRB 000926: Preliminary R-band Lightcurve
  85. GRB 000926 HST/Chandra TOO Status
  86. Spectroscopic Redshift of GRB 000926
  87. GRB 000926, Optical Observation
  88. GRB000926, radio observations
  89. GRB 000926: Optical candidate
  90. Optical candidate for GRB000926
  91. IPN triangulation of GRB000926
  92. IPN triangulation of GRB000926
  93. GRB 000911, BVRI field photometry
  94. GRB000911: Corrected coordinates
  95. GRB000911: Sub-millimeter observations
  96. IPN triangulation of GRB000925
  97. GRB000911: Optical Transient
  98. GRB000911, Radio and Optical observations
  99. GRB000911, Radio observations
  100. GRB000911: Optical observations

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