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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. GRB000812, Radio observations
  2. IPN localization of GRB000812
  3. IPN localization of GRB000811
  4. GRB000801, Gamma Ray Observations
  5. GRB000801, VLT-Antu R-band observations
  6. GRB000301C, UBVI optical observations
  7. GRB000801, Radio Observations
  8. GRB 991208 Host Galaxy Imaging
  9. Updated IPN coordinates for GRB000801
  10. IPN localization of GRB000801
  11. IPN localization of GRB000801
  12. IPN localization of GRB000730B
  13. IPN localization of GRB000730B
  14. IPN localization of GRB000730
  15. GRB 990510: Possible detection of a host galaxy
  16. GRB 990510 Host Galaxy Discovery
  17. GRB 000727, optical observations
  18. IPN localization of GRB000727
  19. GRB 990705, HST/STIS observations of the host galaxy
  20. GRB 990712: Late time HST/STIS Observations
  21. GRB 991216, HST/STIS observations
  22. GRB000620, Radio Observations
  23. GRB981226, HST/STIS observations of the host galaxy
  24. GRB000630, optical observations
  25. GRB 000630: Detection of the Optical Afterglow
  26. GRB000630, Revised BVRI Field Photometry
  27. GRB000630, Optical Observations
  28. GRB000630, optical observations
  29. GRB000630, optical observations
  30. GRB000630, BVRI Field Photometry
  31. GRB000630, optical observations
  32. GRB000630, optical observations
  33. GRB000630: Optical observations
  34. GRB000630, Radio Observations
  35. possible optical counterpart of GRB 000630
  36. IPN triangulation of GRB000630
  37. GRB 000623, optical observations
  38. GRB 000620, optical observations
  39. GRB000418, HST/STIS Observations
  40. GRB990123: Late-time HST/STIS observations of the host
  41. GRB 990506, HST/STIS Observations of the Host Galaxy
  42. GRB000623
  43. GRB 000620: J-band observations
  44. GRB000620, optical observations
  45. GRB000615: H-band observations
  46. GRB990308, HST/STIS observations of the host galaxy
  47. GRB000620 - Optical observations
  48. GRB000620 Optical observations
  49. IPN annulus for GRB000620
  50. GRB000620: BeppoSAX WFC and GRBM detection
  51. GRB000615, Radio observations
  52. GRB000607, optical observations
  53. GRB 000615: NIR further observations
  54. GRB000620: refined BeppoSAX/WFC coordinates
  55. BeppoSAX ALERT: GRB000620
  56. GRB000620: BeppoSAX Alert
  57. GRB990123, HST/STIS observations of the host galaxy
  58. GRB000616 optical observations
  59. GRB 000615, near-infrared observations
  60. GRB 990123: Late-time HST/STIS 50CCD observations of the host
  61. GRB000616 [IPN Position]
  62. GRB000615B [IPN Position]
  63. GRB000615, further R-band photometry
  64. GRB 000615: NIR observations
  65. GRB000615: BeppoSAX NFI follow-up preliminary analysis
  66. GRB000615, R-band photometry
  67. GRB000615: BeppoSAX refined coordinates
  68. GRB980425, HST/STIS observations of the host galaxy
  69. GRB000615: BeppoSAX GRB Alert
  70. The Hosts of GRB 980703 and GRB 971214
  71. GRB 000301C: Further Late-Time HST/STIS observations
  72. GRB000528: follow-up X-ray measurements and update of IPN annulus
  73. Optical Follow-up of GRB000529 Error Box
  74. GRB980519, HST/STIS observations of the host galaxy
  75. GRB000607, Radio Observations
  76. BeppoSAX X-ray transient/possible GRB000608
  77. GRB000604 optical non-detection
  78. GRB000604 - Optical observations
  79. GRB000607, A SHORT, HARD BURST
  80. GRB000604, optical observations
  81. GRB000528, optical observations at ESO
  82. GRB 000604 optical observations
  83. GRB 000418: Detection of the Host Galaxy
  84. GRB000604, optical observations, comparison with DPOSS
  85. GRB000604 [IPN Position]
  86. GRB000528, Radio Observations
  87. X-ray Afterglow of GRB 000529
  88. GRB000529: BeppoSAX NFI follow-up preliminary analysis
  89. GRB000528: BeppoSAX NFI follow-up preliminary analysis
  90. GRB000529: Optical Observations
  91. IPN localization and time history of GRB000528
  92. New IPN localization of GRB000529
  93. GRB000519: Optical observations
  94. IPN localization of GRB000529
  95. GRB 000528 - WFC measurements
  96. GRB000529: BeppoSAX WFC position
  97. GRB000528: BeppoSAX GRBM observations
  98. GRB 000528 Optical Observations
  99. GRB000519, BVRI field photometry
  100. IPN triangulation of GRB000519

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