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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. IPN TRIANGULATION OF GRB001105
  2. GRB 001025B, Optical obervations
  3. GRB 991208: HST Imaging of the Host Galaxy
  4. GRB000926: R-image of the host galaxy
  5. GRB 001025B, I-band observations
  6. XMM-Newton observation of GRB001025
  7. GRB001025B, Radio observations
  8. GRB 001025 Optical Observations
  9. GRB 001025A, optical observation
  10. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  11. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  12. IPN triangulation of GRB001025
  13. GRB001007: Optical observations
  14. ASM Localization of GRB 001025
  15. GRB001007, Radio observations
  16. IPN TRIANGULATION OF GRB001020
  17. GRB001019, Optical Observations
  18. GRB 001018, Possible Radio Afterglow
  19. GRB001018, Gamma Ray Observations
  20. IPN TRIANGULATION OF GRB001019
  21. CORRECTION TO PEAK FLUX OF GRB001018
  22. IPN TRIANGULATION OF GRB001018
  23. IPN TRIANGULATION OF GRB 001017
  24. GRB 000926: Improved Absorber Redshift
  25. V,R,I band observations of GRB000926
  26. The Likely Optical/Infrared Afterglow of GRB 001011
  27. HETE positions added to GCN
  28. GRB001011 BeppoSAX/WFC refined position
  29. BeppoSAX ALERT: GRB001011
  30. GRB 001007, BVR-band observations
  31. GRB000926 - Amateur Optical Observations
  32. GRB001007: Optical observations
  33. CONCAM null result on GRB001005
  34. IPN triangulation of GRB001007
  35. GRB 000926 : the host galaxy
  36. HETE-2 Launches Successfully
  37. IPN triangulation of GRB001005
  38. HETE-2 48 hour Launch Delay
  39. GRB 000926 Chandra Observation
  40. IPN triangulation of GRB 001004
  41. Public availability of BeppoSAX data of GRB000926
  42. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  43. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  44. GRB000926 - Optical observations
  45. GRB000926 - Optical observations
  46. GRB 000926, Optical Decay
  47. GRB000911: VLT infrared observation
  48. GRB000926 - Optical observations
  49. GRB000926 - Optical observations
  50. GRB 000926: optical observations
  51. GRB 000926, Optical Observations
  52. GRB000926 - Optical observations
  53. GRB000911: optical VLT observations
  54. GRB000926 K'-band Observation
  55. GRB000926 : increasing optical decay slope
  56. GRB000926 optical observations
  57. GRB000926 - Optical observations
  58. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  59. J and K band observations of GRB 000926
  60. GRB000911 Optical Observations
  61. GRB 000926: Lightcurve Update and Predictions
  62. GRB 000926, optical observation by Oksanen (vsnet-grb)
  63. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  64. GRB000926: Optical observations
  65. CONCAM crude optical limits before and after GRB000926
  66. GRB 000926: Preliminary R-band Lightcurve
  67. GRB 000926 HST/Chandra TOO Status
  68. Spectroscopic Redshift of GRB 000926
  69. GRB 000926, Optical Observation
  70. GRB000926, radio observations
  71. GRB 000926: Optical candidate
  72. Optical candidate for GRB000926
  73. IPN triangulation of GRB000926
  74. IPN triangulation of GRB000926
  75. GRB 000911, BVRI field photometry
  76. GRB000911: Corrected coordinates
  77. GRB000911: Sub-millimeter observations
  78. IPN triangulation of GRB000925
  79. GRB000911: Optical Transient
  80. GRB000911, Radio and Optical observations
  81. GRB000911, Radio observations
  82. GRB000911: Optical observations
  83. IPN triangulation of GRB000911
  84. IPN triangulation of GRB000910
  85. False GRB alarm from RXTE/ASM on 8 Sept 2000
  86. GRB 000830: Optical observations
  87. GRB000830: Optical observations
  88. GRB000830, TNG B-band observations
  89. GRB000830, BVRI field photometry
  90. GRB000830: Optical observations
  91. GRB000210, Optical observations
  92. Chandra Position of GRB000210
  93. "Snapshot" afterglow IDs and GRB 000830
  94. GRB000830: Optical observations
  95. IPN triangulation of GRB000830
  96. HST/STIS observations of the host galaxy of GRB 980329
  97. HST/STIS observations of the chaotic environment of GRB 980613
  98. IPN localization of GRB000820
  99. SGR 1806-20 burst activity
  100. GRB000812, TNG R-band observations

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