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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. GRB001120: Gunn-i observations
  2. GRB001120: Optical observations
  3. GRB001109, optical observations
  4. GRB001120, optical observations
  5. WSRT 4.8 GHz observations of GRB001109
  6. IPN triangulation of GRB001120
  7. Optical/NIR observations of GRB001109
  8. GRB 001109: deep JHK upper limits
  9. GRB 001109 X-ray afterglow with BeppoSAX
  10. CORRECTION to XMM-Newton observation of GRB001025
  11. GRB001109: Optical observations
  12. GRB001109: BeppoSAX/NFI Observations
  13. GRB001109, R-band optical observations
  14. GRB001109, Radio observations
  15. GRB001109: BeppoSAX refined WFC position
  16. BeppoSAX ALERT: GRB001109
  17. GRB001105 BVRI field photometry correction
  18. GRB001105, BVRI field photometry
  19. GRB 001105, R-band observation
  20. IPN TRIANGULATION OF GRB001105
  21. GRB 001025B, Optical obervations
  22. GRB 991208: HST Imaging of the Host Galaxy
  23. GRB000926: R-image of the host galaxy
  24. GRB 001025B, I-band observations
  25. XMM-Newton observation of GRB001025
  26. GRB001025B, Radio observations
  27. GRB 001025 Optical Observations
  28. GRB 001025A, optical observation
  29. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  30. CORRECTION TO IPN/RXTE ERROR BOX FOR GRB001025
  31. IPN triangulation of GRB001025
  32. GRB001007: Optical observations
  33. ASM Localization of GRB 001025
  34. GRB001007, Radio observations
  35. IPN TRIANGULATION OF GRB001020
  36. GRB001019, Optical Observations
  37. GRB 001018, Possible Radio Afterglow
  38. GRB001018, Gamma Ray Observations
  39. IPN TRIANGULATION OF GRB001019
  40. CORRECTION TO PEAK FLUX OF GRB001018
  41. IPN TRIANGULATION OF GRB001018
  42. IPN TRIANGULATION OF GRB 001017
  43. GRB 000926: Improved Absorber Redshift
  44. V,R,I band observations of GRB000926
  45. The Likely Optical/Infrared Afterglow of GRB 001011
  46. HETE positions added to GCN
  47. GRB001011 BeppoSAX/WFC refined position
  48. BeppoSAX ALERT: GRB001011
  49. GRB 001007, BVR-band observations
  50. GRB000926 - Amateur Optical Observations
  51. GRB001007: Optical observations
  52. CONCAM null result on GRB001005
  53. IPN triangulation of GRB001007
  54. GRB 000926 : the host galaxy
  55. HETE-2 Launches Successfully
  56. IPN triangulation of GRB001005
  57. HETE-2 48 hour Launch Delay
  58. GRB 000926 Chandra Observation
  59. IPN triangulation of GRB 001004
  60. Public availability of BeppoSAX data of GRB000926
  61. GRB000926: X-ray afterglow by BeppoSAX: revised fluxes (fwd)
  62. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  63. GRB000926 - Optical observations
  64. GRB000926 - Optical observations
  65. GRB 000926, Optical Decay
  66. GRB000911: VLT infrared observation
  67. GRB000926 - Optical observations
  68. GRB000926 - Optical observations
  69. GRB 000926: optical observations
  70. GRB 000926, Optical Observations
  71. GRB000926 - Optical observations
  72. GRB000911: optical VLT observations
  73. GRB000926 K'-band Observation
  74. GRB000926 : increasing optical decay slope
  75. GRB000926 optical observations
  76. GRB000926 - Optical observations
  77. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  78. J and K band observations of GRB 000926
  79. GRB000911 Optical Observations
  80. GRB 000926: Lightcurve Update and Predictions
  81. GRB 000926, optical observation by Oksanen (vsnet-grb)
  82. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  83. GRB000926: Optical observations
  84. CONCAM crude optical limits before and after GRB000926
  85. GRB 000926: Preliminary R-band Lightcurve
  86. GRB 000926 HST/Chandra TOO Status
  87. Spectroscopic Redshift of GRB 000926
  88. GRB 000926, Optical Observation
  89. GRB000926, radio observations
  90. GRB 000926: Optical candidate
  91. Optical candidate for GRB000926
  92. IPN triangulation of GRB000926
  93. IPN triangulation of GRB000926
  94. GRB 000911, BVRI field photometry
  95. GRB000911: Corrected coordinates
  96. GRB000911: Sub-millimeter observations
  97. IPN triangulation of GRB000925
  98. GRB000911: Optical Transient
  99. GRB000911, Radio and Optical observations
  100. GRB000911, Radio observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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