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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 GRB001120
  2. Optical/NIR observations of GRB001109
  3. GRB 001109: deep JHK upper limits
  4. GRB 001109 X-ray afterglow with BeppoSAX
  5. CORRECTION to XMM-Newton observation of GRB001025
  6. GRB001109: Optical observations
  7. GRB001109: BeppoSAX/NFI Observations
  8. GRB001109, R-band optical observations
  9. GRB001109, Radio observations
  10. GRB001109: BeppoSAX refined WFC position
  11. BeppoSAX ALERT: GRB001109
  12. GRB001105 BVRI field photometry correction
  13. GRB001105, BVRI field photometry
  14. GRB 001105, R-band observation
  15. IPN TRIANGULATION OF GRB001105
  16. GRB 001025B, Optical obervations
  17. GRB 991208: HST Imaging of the Host Galaxy
  18. GRB000926: R-image of the host galaxy
  19. GRB 001025B, I-band observations
  20. XMM-Newton observation of GRB001025
  21. GRB001025B, Radio observations
  22. GRB 001025 Optical Observations
  23. GRB 001025A, optical observation
  24. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  25. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  26. IPN triangulation of GRB001025
  27. GRB001007: Optical observations
  28. ASM Localization of GRB 001025
  29. GRB001007, Radio observations
  30. IPN TRIANGULATION OF GRB001020
  31. GRB001019, Optical Observations
  32. GRB 001018, Possible Radio Afterglow
  33. GRB001018, Gamma Ray Observations
  34. IPN TRIANGULATION OF GRB001019
  35. CORRECTION TO PEAK FLUX OF GRB001018
  36. IPN TRIANGULATION OF GRB001018
  37. IPN TRIANGULATION OF GRB 001017
  38. GRB 000926: Improved Absorber Redshift
  39. V,R,I band observations of GRB000926
  40. The Likely Optical/Infrared Afterglow of GRB 001011
  41. HETE positions added to GCN
  42. GRB001011 BeppoSAX/WFC refined position
  43. BeppoSAX ALERT: GRB001011
  44. GRB 001007, BVR-band observations
  45. GRB000926 - Amateur Optical Observations
  46. GRB001007: Optical observations
  47. CONCAM null result on GRB001005
  48. IPN triangulation of GRB001007
  49. GRB 000926 : the host galaxy
  50. HETE-2 Launches Successfully
  51. IPN triangulation of GRB001005
  52. HETE-2 48 hour Launch Delay
  53. GRB 000926 Chandra Observation
  54. IPN triangulation of GRB 001004
  55. Public availability of BeppoSAX data of GRB000926
  56. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  57. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  58. GRB000926 - Optical observations
  59. GRB000926 - Optical observations
  60. GRB 000926, Optical Decay
  61. GRB000911: VLT infrared observation
  62. GRB000926 - Optical observations
  63. GRB000926 - Optical observations
  64. GRB 000926: optical observations
  65. GRB 000926, Optical Observations
  66. GRB000926 - Optical observations
  67. GRB000911: optical VLT observations
  68. GRB000926 K'-band Observation
  69. GRB000926 : increasing optical decay slope
  70. GRB000926 optical observations
  71. GRB000926 - Optical observations
  72. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  73. J and K band observations of GRB 000926
  74. GRB000911 Optical Observations
  75. GRB 000926: Lightcurve Update and Predictions
  76. GRB 000926, optical observation by Oksanen (vsnet-grb)
  77. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  78. GRB000926: Optical observations
  79. CONCAM crude optical limits before and after GRB000926
  80. GRB 000926: Preliminary R-band Lightcurve
  81. GRB 000926 HST/Chandra TOO Status
  82. Spectroscopic Redshift of GRB 000926
  83. GRB 000926, Optical Observation
  84. GRB000926, radio observations
  85. GRB 000926: Optical candidate
  86. Optical candidate for GRB000926
  87. IPN triangulation of GRB000926
  88. IPN triangulation of GRB000926
  89. GRB 000911, BVRI field photometry
  90. GRB000911: Corrected coordinates
  91. GRB000911: Sub-millimeter observations
  92. IPN triangulation of GRB000925
  93. GRB000911: Optical Transient
  94. GRB000911, Radio and Optical observations
  95. GRB000911, Radio observations
  96. GRB000911: Optical observations
  97. IPN triangulation of GRB000911
  98. IPN triangulation of GRB000910
  99. False GRB alarm from RXTE/ASM on 8 Sept 2000
  100. GRB 000830: Optical observations

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