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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. GRB990510: optical observation
  2. GRB 990510 Optical Observations
  3. GRB 990510, BVI photometry
  4. GRB 990510 optical observations
  5. GRB 990510: BeppoSAX/GRBM observations
  6. GRB990510 optical observations
  7. GRB990510
  8. GRB 990510 optical observations
  9. GRB 990510 optical observations
  10. Galactic extinction towards GRB 990510
  11. GRB990510: NFI X-ray source
  12. GRB 990510 optical observations
  13. IPN localization of GRB990510
  14. GRB 990506 Radio Observations
  15. GRB 990123, optical monitoring
  16. GRB 990506: BATSE Observations
  17. GRB 990506, optical observations
  18. GRB 990510: Final BeppoSAX-WFC Coordinates
  19. GRB 990506, Optical Observations
  20. GRB 990506 optical observations
  21. GRB 990506 optical observations
  22. GRB 990506, optical observations
  23. GRB990506 observation plan
  24. Refined IPN error box for GRB990506
  25. GRB 990506: Limits on the possible optical transient
  26. GRB 990506, armchair astronomy
  27. GRB 990506, optical observations from +1 to +3 hours
  28. GRB 990506, optical observations
  29. GRB990506 Optical observations
  30. GRB990506 observation plan
  31. New IPN/RXTE error box for GRB990506
  32. IPN localization for GRB990506
  33. GRB 970228: Redshift and properties of the host galaxy
  34. IPN localization of GRB990427
  35. GRB981220 VLBA observations
  36. GRB980425 Optical observations of exponential decline at late time
  37. GRB990321 REFINED IPN ANNULUS
  38. GRB990323 PRECISE IPN POSITION
  39. GRB990321 IPN TRIANGULATION
  40. GRB 990316 Optical Observations
  41. GRB 990316, Radio observations
  42. GRB 990316, Optical observations
  43. GRB990316, Optical observations
  44. GRB 990316 optical observations
  45. GRB990316: simultaneous optical observation
  46. GRB990316 - Optical null results
  47. ASM/IPN error box for GRB 990308 (BATSE #7457)
  48. GRB990308 not a new SGR
  49. GRB 990308a and GRB 990308b
  50. GRB990308 (Trig. 7457), optical observations
  51. GRB990308, Possible new SGR~0209+70
  52. GRB981220, IPN localization
  53. GRB 981220, radio observations
  54. GRB 990123, Field Photometry
  55. GRB 990217 Optical Observations
  56. GRB 990217, radio observations
  57. BATSE Resumes Normal Operations
  58. BATSE Flight Anomaly
  59. GRB990217: BeppoSAX/GRBM data
  60. Optical Observations of GRB990217
  61. GRB990123: Caltech STIS Photometry and Images
  62. GRB990123 observations
  63. GRB990217 Optical observation
  64. GRB990217, WFC position
  65. GRB990123, Optical Observation
  66. GRB 990123: Discovery of the Probable Host Galaxy
  67. GRB 990123: Reduced HST Images
  68. For Immediate Posting to GCN - HST Data GRB 990123 Available
  69. GRB19990123 observations
  70. GRB 990123: BVRI standards in the field
  71. GRB 990123: Updated Keck Spectroscopy Results
  72. GRB981220, field photometry
  73. GRB 990123 NOT Spectrum Update
  74. GRB990123, Optical observation
  75. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  76. GRB 990123: Publicly available reduced HST images
  77. GRB990123, Upcoming HST Service Observations
  78. GRB990123, 15-GHz limits
  79. GRB 990123: New Constraints on Possible Foreground Galaxies
  80. GRB990123 Optical Observations
  81. GRB990123, Probability of gravitational lensing
  82. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  83. GRB 990123: Continued Radio Observations
  84. GRB990123, Preliminary Lens Search Results
  85. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  86. On the Lensing Interpretation of GRB 990123
  87. Search for Potential Images of GRB 990123
  88. Search for Potential Images of GRB 990123
  89. GRB990123, Optical BVRI Observations
  90. GRB 990123: near-infrared observations.
  91. GRB990123, OSSE observations
  92. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
  93. GRB990123: NIR Observation
  94. GRB990123, ASCA X-ray observation of afterglow
  95. "GRB 990123: New BV Observations"
  96. GRB 990123 Optical Follow-Up
  97. GRB 990123; Addendum to GCN 223
  98. GRB 990123: BATSE Observations
  99. GRB 990123 Keck Spectrum update
  100. GRB990123 IPN annulus

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