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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 001109: deep JHK upper limits
  2. GRB 001109 X-ray afterglow with BeppoSAX
  3. CORRECTION to XMM-Newton observation of GRB001025
  4. GRB001109: Optical observations
  5. GRB001109: BeppoSAX/NFI Observations
  6. GRB001109, R-band optical observations
  7. GRB001109, Radio observations
  8. GRB001109: BeppoSAX refined WFC position
  9. BeppoSAX ALERT: GRB001109
  10. GRB001105 BVRI field photometry correction
  11. GRB001105, BVRI field photometry
  12. GRB 001105, R-band observation
  13. IPN TRIANGULATION OF GRB001105
  14. GRB 001025B, Optical obervations
  15. GRB 991208: HST Imaging of the Host Galaxy
  16. GRB000926: R-image of the host galaxy
  17. GRB 001025B, I-band observations
  18. XMM-Newton observation of GRB001025
  19. GRB001025B, Radio observations
  20. GRB 001025 Optical Observations
  21. GRB 001025A, optical observation
  22. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  23. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  24. IPN triangulation of GRB001025
  25. GRB001007: Optical observations
  26. ASM Localization of GRB 001025
  27. GRB001007, Radio observations
  28. IPN TRIANGULATION OF GRB001020
  29. GRB001019, Optical Observations
  30. GRB 001018, Possible Radio Afterglow
  31. GRB001018, Gamma Ray Observations
  32. IPN TRIANGULATION OF GRB001019
  33. CORRECTION TO PEAK FLUX OF GRB001018
  34. IPN TRIANGULATION OF GRB001018
  35. IPN TRIANGULATION OF GRB 001017
  36. GRB 000926: Improved Absorber Redshift
  37. V,R,I band observations of GRB000926
  38. The Likely Optical/Infrared Afterglow of GRB 001011
  39. HETE positions added to GCN
  40. GRB001011 BeppoSAX/WFC refined position
  41. BeppoSAX ALERT: GRB001011
  42. GRB 001007, BVR-band observations
  43. GRB000926 - Amateur Optical Observations
  44. GRB001007: Optical observations
  45. CONCAM null result on GRB001005
  46. IPN triangulation of GRB001007
  47. GRB 000926 : the host galaxy
  48. HETE-2 Launches Successfully
  49. IPN triangulation of GRB001005
  50. HETE-2 48 hour Launch Delay
  51. GRB 000926 Chandra Observation
  52. IPN triangulation of GRB 001004
  53. Public availability of BeppoSAX data of GRB000926
  54. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  55. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  56. GRB000926 - Optical observations
  57. GRB000926 - Optical observations
  58. GRB 000926, Optical Decay
  59. GRB000911: VLT infrared observation
  60. GRB000926 - Optical observations
  61. GRB000926 - Optical observations
  62. GRB 000926: optical observations
  63. GRB 000926, Optical Observations
  64. GRB000926 - Optical observations
  65. GRB000911: optical VLT observations
  66. GRB000926 K'-band Observation
  67. GRB000926 : increasing optical decay slope
  68. GRB000926 optical observations
  69. GRB000926 - Optical observations
  70. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  71. J and K band observations of GRB 000926
  72. GRB000911 Optical Observations
  73. GRB 000926: Lightcurve Update and Predictions
  74. GRB 000926, optical observation by Oksanen (vsnet-grb)
  75. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  76. GRB000926: Optical observations
  77. CONCAM crude optical limits before and after GRB000926
  78. GRB 000926: Preliminary R-band Lightcurve
  79. GRB 000926 HST/Chandra TOO Status
  80. Spectroscopic Redshift of GRB 000926
  81. GRB 000926, Optical Observation
  82. GRB000926, radio observations
  83. GRB 000926: Optical candidate
  84. Optical candidate for GRB000926
  85. IPN triangulation of GRB000926
  86. IPN triangulation of GRB000926
  87. GRB 000911, BVRI field photometry
  88. GRB000911: Corrected coordinates
  89. GRB000911: Sub-millimeter observations
  90. IPN triangulation of GRB000925
  91. GRB000911: Optical Transient
  92. GRB000911, Radio and Optical observations
  93. GRB000911, Radio observations
  94. GRB000911: Optical observations
  95. IPN triangulation of GRB000911
  96. IPN triangulation of GRB000910
  97. False GRB alarm from RXTE/ASM on 8 Sept 2000
  98. GRB 000830: Optical observations
  99. GRB000830: Optical observations
  100. GRB000830, TNG B-band observations

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