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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. GRB000911: VLT infrared observation
  2. GRB000926 - Optical observations
  3. GRB000926 - Optical observations
  4. GRB 000926: optical observations
  5. GRB 000926, Optical Observations
  6. GRB000926 - Optical observations
  7. GRB000911: optical VLT observations
  8. GRB000926 K'-band Observation
  9. GRB000926 : increasing optical decay slope
  10. GRB000926 optical observations
  11. GRB000926 - Optical observations
  12. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  13. J and K band observations of GRB 000926
  14. GRB000911 Optical Observations
  15. GRB 000926: Lightcurve Update and Predictions
  16. GRB 000926, optical observation by Oksanen (vsnet-grb)
  17. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  18. GRB000926: Optical observations
  19. CONCAM crude optical limits before and after GRB000926
  20. GRB 000926: Preliminary R-band Lightcurve
  21. GRB 000926 HST/Chandra TOO Status
  22. Spectroscopic Redshift of GRB 000926
  23. GRB 000926, Optical Observation
  24. GRB000926, radio observations
  25. GRB 000926: Optical candidate
  26. Optical candidate for GRB000926
  27. IPN triangulation of GRB000926
  28. IPN triangulation of GRB000926
  29. GRB 000911, BVRI field photometry
  30. GRB000911: Corrected coordinates
  31. GRB000911: Sub-millimeter observations
  32. IPN triangulation of GRB000925
  33. GRB000911: Optical Transient
  34. GRB000911, Radio and Optical observations
  35. GRB000911, Radio observations
  36. GRB000911: Optical observations
  37. IPN triangulation of GRB000911
  38. IPN triangulation of GRB000910
  39. False GRB alarm from RXTE/ASM on 8 Sept 2000
  40. GRB 000830: Optical observations
  41. GRB000830: Optical observations
  42. GRB000830, TNG B-band observations
  43. GRB000830, BVRI field photometry
  44. GRB000830: Optical observations
  45. GRB000210, Optical observations
  46. Chandra Position of GRB000210
  47. "Snapshot" afterglow IDs and GRB 000830
  48. GRB000830: Optical observations
  49. IPN triangulation of GRB000830
  50. HST/STIS observations of the host galaxy of GRB 980329
  51. HST/STIS observations of the chaotic environment of GRB 980613
  52. IPN localization of GRB000820
  53. SGR 1806-20 burst activity
  54. GRB000812, TNG R-band observations
  55. GRB000801 & GRB000730, Gamma Ray Observations
  56. GRB000730, Gamma Ray Observations
  57. GRB000812, Radio observations
  58. IPN localization of GRB000812
  59. IPN localization of GRB000811
  60. GRB000801, Gamma Ray Observations
  61. GRB000801, VLT-Antu R-band observations
  62. GRB000301C, UBVI optical observations
  63. GRB000801, Radio Observations
  64. GRB 991208 Host Galaxy Imaging
  65. Updated IPN coordinates for GRB000801
  66. IPN localization of GRB000801
  67. IPN localization of GRB000801
  68. IPN localization of GRB000730B
  69. IPN localization of GRB000730B
  70. IPN localization of GRB000730
  71. GRB 990510: Possible detection of a host galaxy
  72. GRB 990510 Host Galaxy Discovery
  73. GRB 000727, optical observations
  74. IPN localization of GRB000727
  75. GRB 990705, HST/STIS observations of the host galaxy
  76. GRB 990712: Late time HST/STIS Observations
  77. GRB 991216, HST/STIS observations
  78. GRB000620, Radio Observations
  79. GRB981226, HST/STIS observations of the host galaxy
  80. GRB000630, optical observations
  81. GRB 000630: Detection of the Optical Afterglow
  82. GRB000630, Revised BVRI Field Photometry
  83. GRB000630, Optical Observations
  84. GRB000630, optical observations
  85. GRB000630, optical observations
  86. GRB000630, BVRI Field Photometry
  87. GRB000630, optical observations
  88. GRB000630, optical observations
  89. GRB000630: Optical observations
  90. GRB000630, Radio Observations
  91. possible optical counterpart of GRB 000630
  92. IPN triangulation of GRB000630
  93. GRB 000623, optical observations
  94. GRB 000620, optical observations
  95. GRB000418, HST/STIS Observations
  96. GRB990123: Late-time HST/STIS observations of the host
  97. GRB 990506, HST/STIS Observations of the Host Galaxy
  98. GRB000623
  99. GRB 000620: J-band observations
  100. GRB000620, optical observations

Advanced

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