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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"

32801 results found.

  1. GRB001109: Optical observations
  2. GRB001109: BeppoSAX/NFI Observations
  3. GRB001109, R-band optical observations
  4. GRB001109, Radio observations
  5. BeppoSAX ALERT: GRB001109
  6. GRB001105 BVRI field photometry correction
  7. GRB001105, BVRI field photometry
  8. GRB 001105, R-band observation
  9. IPN TRIANGULATION OF GRB001105
  10. GRB 001025B, Optical obervations
  11. GRB 991208: HST Imaging of the Host Galaxy
  12. GRB000926: R-image of the host galaxy
  13. GRB 001025B, I-band observations
  14. GRB 001025 Optical Observations
  15. GRB 001025A, optical observation
  16. IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
  17. IPN triangulation of GRB001025
  18. ASM Localization of GRB 001025
  19. GRB001007, Radio observations
  20. IPN TRIANGULATION OF GRB001020
  21. GRB001019, Optical Observations
  22. GRB 001018, Possible Radio Afterglow
  23. GRB001018, Gamma Ray Observations
  24. IPN TRIANGULATION OF GRB001019
  25. IPN TRIANGULATION OF GRB001018
  26. IPN TRIANGULATION OF GRB 001017
  27. GRB 000926: Improved Absorber Redshift
  28. V,R,I band observations of GRB000926
  29. The Likely Optical/Infrared Afterglow of GRB 001011
  30. HETE positions added to GCN
  31. BeppoSAX ALERT: GRB001011
  32. GRB 001007, BVR-band observations
  33. GRB000926 - Amateur Optical Observations
  34. CONCAM null result on GRB001005
  35. IPN triangulation of GRB001007
  36. GRB 000926 : the host galaxy
  37. IPN triangulation of GRB001005
  38. GRB 000926 Chandra Observation
  39. IPN triangulation of GRB 001004
  40. Public availability of BeppoSAX data of GRB000926
  41. GRB000926: X-ray afterglow by BeppoSAX. Refined analysis
  42. GRB 000926, Optical Decay
  43. GRB000926 - Optical observations
  44. GRB000926 - Optical observations
  45. GRB 000926: optical observations
  46. GRB 000926, Optical Observations
  47. GRB000926 K'-band Observation
  48. GRB000926 : increasing optical decay slope
  49. GRB000926 optical observations
  50. GRB000926 - Optical observations
  51. Re: GRB 000926, optical observation by Oksanen (vsnet-grb)
  52. J and K band observations of GRB 000926
  53. GRB 000926: Lightcurve Update and Predictions
  54. GRB 000926, optical observation by Oksanen (vsnet-grb)
  55. GRB000926: X-ray afterglow by BeppoSAX & plan of BSAX & Chandra obs.
  56. CONCAM crude optical limits before and after GRB000926
  57. GRB 000926: Preliminary R-band Lightcurve
  58. GRB 000926 HST/Chandra TOO Status
  59. Spectroscopic Redshift of GRB 000926
  60. GRB 000926, Optical Observation
  61. GRB 000926: Optical candidate
  62. Optical candidate for GRB000926
  63. IPN triangulation of GRB000926
  64. GRB 000911, BVRI field photometry
  65. GRB000911: Sub-millimeter observations
  66. IPN triangulation of GRB000925
  67. IPN triangulation of GRB000911
  68. IPN triangulation of GRB000910
  69. False GRB alarm from RXTE/ASM on 8 Sept 2000
  70. GRB 000830: Optical observations
  71. GRB000830: Optical observations
  72. GRB000830, TNG B-band observations
  73. GRB000830, BVRI field photometry
  74. GRB000830: Optical observations
  75. GRB000210, Optical observations
  76. Chandra Position of GRB000210
  77. "Snapshot" afterglow IDs and GRB 000830
  78. IPN triangulation of GRB000830
  79. HST/STIS observations of the host galaxy of GRB 980329
  80. HST/STIS observations of the chaotic environment of GRB 980613
  81. IPN localization of GRB000820
  82. GRB000801 & GRB000730, Gamma Ray Observations
  83. GRB000730, Gamma Ray Observations
  84. GRB000812, Radio observations
  85. IPN localization of GRB000812
  86. IPN localization of GRB000811
  87. GRB000801, Gamma Ray Observations
  88. GRB000801, VLT-Antu R-band observations
  89. GRB 991208 Host Galaxy Imaging
  90. Updated IPN coordinates for GRB000801
  91. IPN localization of GRB000801
  92. IPN localization of GRB000730B
  93. IPN localization of GRB000730B
  94. IPN localization of GRB000730
  95. GRB 990510: Possible detection of a host galaxy
  96. GRB 990510 Host Galaxy Discovery
  97. GRB 000727, optical observations
  98. IPN localization of GRB000727
  99. GRB 990705, HST/STIS observations of the host galaxy
  100. GRB 990712: Late time HST/STIS Observations

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