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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. Confirmation of IPN position for GRB001204
  2. GRB001204, Radio observations
  3. IPN triangulation of GRB001204 (short/hard)
  4. GRB 001105, further optical observations
  5. GRB001120: Gunn-i observations
  6. GRB001120: Optical observations
  7. GRB001109, optical observations
  8. GRB001120, optical observations
  9. WSRT 4.8 GHz observations of GRB001109
  10. IPN triangulation of GRB001120
  11. Optical/NIR observations of GRB001109
  12. GRB 001109: deep JHK upper limits
  13. GRB 001109 X-ray afterglow with BeppoSAX
  14. CORRECTION to XMM-Newton observation of GRB001025
  15. GRB001109: Optical observations
  16. GRB001109: BeppoSAX/NFI Observations
  17. GRB001109, R-band optical observations
  18. GRB001109, Radio observations
  19. GRB001109: BeppoSAX refined WFC position
  20. BeppoSAX ALERT: GRB001109
  21. GRB001105 BVRI field photometry correction
  22. GRB001105, BVRI field photometry
  23. GRB 001105, R-band observation
  24. IPN TRIANGULATION OF GRB001105
  25. GRB 001025B, Optical obervations
  26. GRB 991208: HST Imaging of the Host Galaxy
  27. GRB000926: R-image of the host galaxy
  28. GRB 001025B, I-band observations
  29. XMM-Newton observation of GRB001025
  30. GRB001025B, Radio observations
  31. GRB 001025 Optical Observations
  32. GRB 001025A, optical observation
  33. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  34. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  35. IPN triangulation of GRB001025
  36. GRB001007: Optical observations
  37. ASM Localization of GRB 001025
  38. GRB001007, Radio observations
  39. IPN TRIANGULATION OF GRB001020
  40. GRB001019, Optical Observations
  41. GRB 001018, Possible Radio Afterglow
  42. GRB001018, Gamma Ray Observations
  43. IPN TRIANGULATION OF GRB001019
  44. CORRECTION TO PEAK FLUX OF GRB001018
  45. IPN TRIANGULATION OF GRB001018
  46. IPN TRIANGULATION OF GRB 001017
  47. GRB 000926: Improved Absorber Redshift
  48. V,R,I band observations of GRB000926
  49. The Likely Optical/Infrared Afterglow of GRB 001011
  50. HETE positions added to GCN
  51. GRB001011 BeppoSAX/WFC refined position
  52. BeppoSAX ALERT: GRB001011
  53. GRB 001007, BVR-band observations
  54. GRB000926 - Amateur Optical Observations
  55. GRB001007: Optical observations
  56. CONCAM null result on GRB001005
  57. IPN triangulation of GRB001007
  58. GRB 000926 : the host galaxy
  59. HETE-2 Launches Successfully
  60. IPN triangulation of GRB001005
  61. HETE-2 48 hour Launch Delay
  62. GRB 000926 Chandra Observation
  63. IPN triangulation of GRB 001004
  64. Public availability of BeppoSAX data of GRB000926
  65. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  66. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  67. GRB000926 - Optical observations
  68. GRB000926 - Optical observations
  69. GRB 000926, Optical Decay
  70. GRB000911: VLT infrared observation
  71. GRB000926 - Optical observations
  72. GRB000926 - Optical observations
  73. GRB 000926: optical observations
  74. GRB 000926, Optical Observations
  75. GRB000926 - Optical observations
  76. GRB000911: optical VLT observations
  77. GRB000926 K'-band Observation
  78. GRB000926 : increasing optical decay slope
  79. GRB000926 optical observations
  80. GRB000926 - Optical observations
  81. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  82. J and K band observations of GRB 000926
  83. GRB000911 Optical Observations
  84. GRB 000926: Lightcurve Update and Predictions
  85. GRB 000926, optical observation by Oksanen (vsnet-grb)
  86. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  87. GRB000926: Optical observations
  88. CONCAM crude optical limits before and after GRB000926
  89. GRB 000926: Preliminary R-band Lightcurve
  90. GRB 000926 HST/Chandra TOO Status
  91. Spectroscopic Redshift of GRB 000926
  92. GRB 000926, Optical Observation
  93. GRB000926, radio observations
  94. GRB 000926: Optical candidate
  95. Optical candidate for GRB000926
  96. IPN triangulation of GRB000926
  97. IPN triangulation of GRB000926
  98. GRB 000911, BVRI field photometry
  99. GRB000911: Corrected coordinates
  100. GRB000911: Sub-millimeter observations

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