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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"

19089 results found.

  1. GRB 010222, Decay Slope Confirmed
  2. GRB010222, radio observations
  3. GRB010222, optical observations
  4. GRB 010220, simultaneous optical observations
  5. GRB010220: BeppoSAX WFC and GRBM preliminary data
  6. GRB010214, optical observations
  7. GRB010214: BeppoSAX WFC and GRBM preliminary data
  8. GRB 010214: X-Ray afterglow
  9. GRB 010214 optical observation
  10. J-Band Observation of GRB 010214.
  11. GRB010214, optical observations
  12. GRB010213, optical observations
  13. GRB010213, Near-IR observations
  14. Possible InfraRed Transient of GRB 010214.
  15. GRB010214 Optical Observation
  16. GRB010213 detected by HETE
  17. HETE Status
  18. Optical Observations of GRB 001018 at Keck
  19. Optical observations of GRB 001018 with JCAM
  20. IPN TRIANGULATION OF GRB010109
  21. IPN triangulation of GRB010104
  22. IPN triangulation of GRB010103
  23. IPN triangulation of GRB001219
  24. GRB 001212 Optical Observation
  25. GRB 001212 Optical Observation
  26. GRB001120, optical observations
  27. GRB 001109: deep JHK upper limits
  28. GRB 001109 X-ray afterglow with BeppoSAX
  29. CORRECTION to XMM-Newton observation of GRB001025
  30. GRB001109, Radio observations
  31. GRB001105 BVRI field photometry correction
  32. GRB001105, BVRI field photometry
  33. GRB 001025B, Optical obervations
  34. GRB 991208: HST Imaging of the Host Galaxy
  35. GRB 001025B, I-band observations
  36. GRB 001025A, optical observation
  37. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  38. GRB001007: Optical observations
  39. GRB001007, Radio observations
  40. IPN TRIANGULATION OF GRB001020
  41. CORRECTION TO PEAK FLUX OF GRB001018
  42. IPN TRIANGULATION OF GRB 001017
  43. V,R,I band observations of GRB000926
  44. GRB000926 - Amateur Optical Observations
  45. CONCAM null result on GRB001005
  46. GRB000926 - Optical observations
  47. GRB000926 - Optical observations
  48. GRB 000926, Optical Observations
  49. GRB000926 K'-band Observation
  50. J and K band observations of GRB 000926
  51. CONCAM crude optical limits before and after GRB000926
  52. GRB 000926: Optical candidate
  53. Optical candidate for GRB000926
  54. GRB 000911, BVRI field photometry
  55. GRB000911, Radio and Optical observations
  56. GRB000911: Optical observations
  57. False GRB alarm from RXTE/ASM on 8 Sept 2000
  58. GRB000830, BVRI field photometry
  59. GRB000830: Optical observations
  60. IPN localization of GRB000820
  61. IPN localization of GRB000812
  62. GRB000801, VLT-Antu R-band observations
  63. GRB 991208 Host Galaxy Imaging
  64. IPN localization of GRB000730B
  65. IPN localization of GRB000730B
  66. GRB 990510: Possible detection of a host galaxy
  67. GRB 990510 Host Galaxy Discovery
  68. GRB 990712: Late time HST/STIS Observations
  69. GRB 991216, HST/STIS observations
  70. GRB000630, optical observations
  71. GRB000630, Revised BVRI Field Photometry
  72. GRB000630, Optical Observations
  73. GRB000630, optical observations
  74. GRB000630, optical observations
  75. GRB000630, BVRI Field Photometry
  76. GRB000630, optical observations
  77. GRB000630, optical observations
  78. GRB000630: Optical observations
  79. possible optical counterpart of GRB 000630
  80. IPN triangulation of GRB000630
  81. GRB 000620, optical observations
  82. GRB000418, HST/STIS Observations
  83. GRB990123: Late-time HST/STIS observations of the host
  84. GRB000620, optical observations
  85. GRB000620 - Optical observations
  86. GRB000620 Optical observations
  87. GRB000620: BeppoSAX WFC and GRBM detection
  88. GRB000607, optical observations
  89. GRB 000615: NIR further observations
  90. GRB000616 optical observations
  91. GRB 990123: Late-time HST/STIS 50CCD observations of the host
  92. GRB000615, further R-band photometry
  93. GRB 000615: NIR observations
  94. GRB000615: BeppoSAX NFI follow-up preliminary analysis
  95. GRB000615, R-band photometry
  96. GRB 000301C: Further Late-Time HST/STIS observations
  97. GRB000528: follow-up X-ray measurements and update of IPN annulus
  98. BeppoSAX X-ray transient/possible GRB000608
  99. GRB000604 - Optical observations
  100. GRB000607, A SHORT, HARD BURST

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