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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 001212 possible OA
  2. IPN triangulation of GRB001212
  3. GRB001204: Optical observations
  4. Confirmation of IPN position for GRB001204
  5. GRB001204, Radio observations
  6. IPN triangulation of GRB001204 (short/hard)
  7. GRB 001105, further optical observations
  8. GRB001120: Gunn-i observations
  9. GRB001120: Optical observations
  10. GRB001109, optical observations
  11. GRB001120, optical observations
  12. WSRT 4.8 GHz observations of GRB001109
  13. IPN triangulation of GRB001120
  14. Optical/NIR observations of GRB001109
  15. GRB 001109: deep JHK upper limits
  16. GRB 001109 X-ray afterglow with BeppoSAX
  17. CORRECTION to XMM-Newton observation of GRB001025
  18. GRB001109: Optical observations
  19. GRB001109: BeppoSAX/NFI Observations
  20. GRB001109, R-band optical observations
  21. GRB001109, Radio observations
  22. GRB001109: BeppoSAX refined WFC position
  23. BeppoSAX ALERT: GRB001109
  24. GRB001105 BVRI field photometry correction
  25. GRB001105, BVRI field photometry
  26. GRB 001105, R-band observation
  27. IPN TRIANGULATION OF GRB001105
  28. GRB 001025B, Optical obervations
  29. GRB 991208: HST Imaging of the Host Galaxy
  30. GRB000926: R-image of the host galaxy
  31. GRB 001025B, I-band observations
  32. XMM-Newton observation of GRB001025
  33. GRB001025B, Radio observations
  34. GRB 001025 Optical Observations
  35. GRB 001025A, optical observation
  36. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  37. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  38. IPN triangulation of GRB001025
  39. GRB001007: Optical observations
  40. ASM Localization of GRB 001025
  41. GRB001007, Radio observations
  42. IPN TRIANGULATION OF GRB001020
  43. GRB001019, Optical Observations
  44. GRB 001018, Possible Radio Afterglow
  45. GRB001018, Gamma Ray Observations
  46. IPN TRIANGULATION OF GRB001019
  47. CORRECTION TO PEAK FLUX OF GRB001018
  48. IPN TRIANGULATION OF GRB001018
  49. IPN TRIANGULATION OF GRB 001017
  50. GRB 000926: Improved Absorber Redshift
  51. V,R,I band observations of GRB000926
  52. The Likely Optical/Infrared Afterglow of GRB 001011
  53. HETE positions added to GCN
  54. GRB001011 BeppoSAX/WFC refined position
  55. BeppoSAX ALERT: GRB001011
  56. GRB 001007, BVR-band observations
  57. GRB000926 - Amateur Optical Observations
  58. GRB001007: Optical observations
  59. CONCAM null result on GRB001005
  60. IPN triangulation of GRB001007
  61. GRB 000926 : the host galaxy
  62. HETE-2 Launches Successfully
  63. IPN triangulation of GRB001005
  64. HETE-2 48 hour Launch Delay
  65. GRB 000926 Chandra Observation
  66. IPN triangulation of GRB 001004
  67. Public availability of BeppoSAX data of GRB000926
  68. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  69. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  70. GRB000926 - Optical observations
  71. GRB000926 - Optical observations
  72. GRB 000926, Optical Decay
  73. GRB000911: VLT infrared observation
  74. GRB000926 - Optical observations
  75. GRB000926 - Optical observations
  76. GRB 000926: optical observations
  77. GRB 000926, Optical Observations
  78. GRB000926 - Optical observations
  79. GRB000911: optical VLT observations
  80. GRB000926 K'-band Observation
  81. GRB000926 : increasing optical decay slope
  82. GRB000926 optical observations
  83. GRB000926 - Optical observations
  84. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  85. J and K band observations of GRB 000926
  86. GRB000911 Optical Observations
  87. GRB 000926: Lightcurve Update and Predictions
  88. GRB 000926, optical observation by Oksanen (vsnet-grb)
  89. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  90. GRB000926: Optical observations
  91. CONCAM crude optical limits before and after GRB000926
  92. GRB 000926: Preliminary R-band Lightcurve
  93. GRB 000926 HST/Chandra TOO Status
  94. Spectroscopic Redshift of GRB 000926
  95. GRB 000926, Optical Observation
  96. GRB000926, radio observations
  97. GRB 000926: Optical candidate
  98. Optical candidate for GRB000926
  99. IPN triangulation of GRB000926
  100. IPN triangulation of GRB000926

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