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

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