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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. GRB000926: R-image of the host galaxy
  2. GRB 001025B, I-band observations
  3. XMM-Newton observation of GRB001025
  4. GRB001025B, Radio observations
  5. GRB 001025 Optical Observations
  6. GRB 001025A, optical observation
  7. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  8. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  9. IPN triangulation of GRB001025
  10. GRB001007: Optical observations
  11. ASM Localization of GRB 001025
  12. GRB001007, Radio observations
  13. IPN TRIANGULATION OF GRB001020
  14. GRB001019, Optical Observations
  15. GRB 001018, Possible Radio Afterglow
  16. GRB001018, Gamma Ray Observations
  17. IPN TRIANGULATION OF GRB001019
  18. CORRECTION TO PEAK FLUX OF GRB001018
  19. IPN TRIANGULATION OF GRB001018
  20. IPN TRIANGULATION OF GRB 001017
  21. GRB 000926: Improved Absorber Redshift
  22. V,R,I band observations of GRB000926
  23. The Likely Optical/Infrared Afterglow of GRB 001011
  24. HETE positions added to GCN
  25. GRB001011 BeppoSAX/WFC refined position
  26. BeppoSAX ALERT: GRB001011
  27. GRB 001007, BVR-band observations
  28. GRB000926 - Amateur Optical Observations
  29. GRB001007: Optical observations
  30. CONCAM null result on GRB001005
  31. IPN triangulation of GRB001007
  32. GRB 000926 : the host galaxy
  33. HETE-2 Launches Successfully
  34. IPN triangulation of GRB001005
  35. HETE-2 48 hour Launch Delay
  36. GRB 000926 Chandra Observation
  37. IPN triangulation of GRB 001004
  38. Public availability of BeppoSAX data of GRB000926
  39. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  40. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  41. GRB000926 - Optical observations
  42. GRB000926 - Optical observations
  43. GRB 000926, Optical Decay
  44. GRB000911: VLT infrared observation
  45. GRB000926 - Optical observations
  46. GRB000926 - Optical observations
  47. GRB 000926: optical observations
  48. GRB 000926, Optical Observations
  49. GRB000926 - Optical observations
  50. GRB000911: optical VLT observations
  51. GRB000926 K'-band Observation
  52. GRB000926 : increasing optical decay slope
  53. GRB000926 optical observations
  54. GRB000926 - Optical observations
  55. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  56. J and K band observations of GRB 000926
  57. GRB000911 Optical Observations
  58. GRB 000926: Lightcurve Update and Predictions
  59. GRB 000926, optical observation by Oksanen (vsnet-grb)
  60. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  61. GRB000926: Optical observations
  62. CONCAM crude optical limits before and after GRB000926
  63. GRB 000926: Preliminary R-band Lightcurve
  64. GRB 000926 HST/Chandra TOO Status
  65. Spectroscopic Redshift of GRB 000926
  66. GRB 000926, Optical Observation
  67. GRB000926, radio observations
  68. GRB 000926: Optical candidate
  69. Optical candidate for GRB000926
  70. IPN triangulation of GRB000926
  71. IPN triangulation of GRB000926
  72. GRB 000911, BVRI field photometry
  73. GRB000911: Corrected coordinates
  74. GRB000911: Sub-millimeter observations
  75. IPN triangulation of GRB000925
  76. GRB000911: Optical Transient
  77. GRB000911, Radio and Optical observations
  78. GRB000911, Radio observations
  79. GRB000911: Optical observations
  80. IPN triangulation of GRB000911
  81. IPN triangulation of GRB000910
  82. False GRB alarm from RXTE/ASM on 8 Sept 2000
  83. GRB 000830: Optical observations
  84. GRB000830: Optical observations
  85. GRB000830, TNG B-band observations
  86. GRB000830, BVRI field photometry
  87. GRB000830: Optical observations
  88. GRB000210, Optical observations
  89. Chandra Position of GRB000210
  90. "Snapshot" afterglow IDs and GRB 000830
  91. GRB000830: Optical observations
  92. IPN triangulation of GRB000830
  93. HST/STIS observations of the host galaxy of GRB 980329
  94. HST/STIS observations of the chaotic environment of GRB 980613
  95. IPN localization of GRB000820
  96. SGR 1806-20 burst activity
  97. GRB000812, TNG R-band observations
  98. GRB000801 & GRB000730, Gamma Ray Observations
  99. GRB000730, Gamma Ray Observations
  100. GRB000812, Radio observations

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