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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').
  1. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  2. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  3. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  4. radio observations of X-ray/GRB transient field
  5. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  6. Optical report on X-ray/GRB transient
  7. radio detection of X-ray/GRB transient
  8. BeppoSAX: A new fast X-ray transient
  9. GRB 990510: optical observations
  10. GRB990510: photometric and spectroscopic observations with the VLT
  11. GRB 990510: optical linear polarization
  12. GRB 990510: optical observations
  13. GRB990510, VI observations
  14. GRB 990506 R band observations
  15. GRB990510: X-ray afterglow
  16. GRB 990510: optical observation
  17. VLT spectrum of GRB990510
  18. GRB 990510: Broad Band Break
  19. GRB 990510: BATSE Observations
  20. GRB990510: optical observation
  21. GRB 990510 Optical Observations
  22. GRB 990510, BVI photometry
  23. GRB 990510 optical observations
  24. GRB 990510: BeppoSAX/GRBM observations
  25. GRB990510 optical observations
  26. GRB990510
  27. GRB 990510 optical observations
  28. GRB 990510 optical observations
  29. Galactic extinction towards GRB 990510
  30. GRB990510: NFI X-ray source
  31. GRB 990510 optical observations
  32. IPN localization of GRB990510
  33. GRB 990506 Radio Observations
  34. GRB 990123, optical monitoring
  35. GRB 990506: BATSE Observations
  36. GRB 990506, optical observations
  37. GRB 990510: Final BeppoSAX-WFC Coordinates
  38. GRB 990506, Optical Observations
  39. GRB 990506 optical observations
  40. GRB 990506 optical observations
  41. GRB 990506, optical observations
  42. GRB990506 observation plan
  43. Refined IPN error box for GRB990506
  44. GRB 990506: Limits on the possible optical transient
  45. GRB 990506, armchair astronomy
  46. GRB 990506, optical observations from +1 to +3 hours
  47. GRB 990506, optical observations
  48. GRB990506 Optical observations
  49. GRB990506 observation plan
  50. New IPN/RXTE error box for GRB990506
  51. IPN localization for GRB990506
  52. GRB 970228: Redshift and properties of the host galaxy
  53. IPN localization of GRB990427
  54. GRB981220 VLBA observations
  55. GRB980425 Optical observations of exponential decline at late time
  56. GRB990321 REFINED IPN ANNULUS
  57. GRB990323 PRECISE IPN POSITION
  58. GRB990321 IPN TRIANGULATION
  59. GRB 990316 Optical Observations
  60. GRB 990316, Radio observations
  61. GRB 990316, Optical observations
  62. GRB990316, Optical observations
  63. GRB 990316 optical observations
  64. GRB990316: simultaneous optical observation
  65. GRB990316 - Optical null results
  66. ASM/IPN error box for GRB 990308 (BATSE #7457)
  67. GRB990308 not a new SGR
  68. GRB 990308a and GRB 990308b
  69. GRB990308 (Trig. 7457), optical observations
  70. GRB990308, Possible new SGR~0209+70
  71. GRB981220, IPN localization
  72. GRB 981220, radio observations
  73. GRB 990123, Field Photometry
  74. GRB 990217 Optical Observations
  75. GRB 990217, radio observations
  76. BATSE Resumes Normal Operations
  77. BATSE Flight Anomaly
  78. GRB990217: BeppoSAX/GRBM data
  79. Optical Observations of GRB990217
  80. GRB990123: Caltech STIS Photometry and Images
  81. GRB990123 observations
  82. GRB990217 Optical observation
  83. GRB990217, WFC position
  84. GRB990123, Optical Observation
  85. GRB 990123: Discovery of the Probable Host Galaxy
  86. GRB 990123: Reduced HST Images
  87. For Immediate Posting to GCN - HST Data GRB 990123 Available
  88. GRB19990123 observations
  89. GRB 990123: BVRI standards in the field
  90. GRB 990123: Updated Keck Spectroscopy Results
  91. GRB981220, field photometry
  92. GRB 990123 NOT Spectrum Update
  93. GRB990123, Optical observation
  94. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  95. GRB 990123: Publicly available reduced HST images
  96. GRB990123, Upcoming HST Service Observations
  97. GRB990123, 15-GHz limits
  98. GRB 990123: New Constraints on Possible Foreground Galaxies
  99. GRB990123 Optical Observations
  100. GRB990123, Probability of gravitational lensing

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