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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"

36295 results found.

  1. GRB 990506 optical observation
  2. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  3. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  4. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  5. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  6. radio observations of X-ray/GRB transient field
  7. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  8. Optical report on X-ray/GRB transient
  9. radio detection of X-ray/GRB transient
  10. BeppoSAX: A new fast X-ray transient
  11. GRB 990510: optical observations
  12. GRB990510: photometric and spectroscopic observations with the VLT
  13. GRB 990510: optical linear polarization
  14. GRB 990510: optical observations
  15. GRB990510, VI observations
  16. GRB 990506 R band observations
  17. GRB990510: X-ray afterglow
  18. GRB 990510: optical observation
  19. VLT spectrum of GRB990510
  20. GRB 990510: Broad Band Break
  21. GRB 990510: BATSE Observations
  22. GRB 990510 Optical Observations
  23. GRB 990510, BVI photometry
  24. GRB 990510 optical observations
  25. GRB 990510: BeppoSAX/GRBM observations
  26. GRB990510 optical observations
  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 observation plan
  49. New IPN/RXTE error box for GRB990506
  50. IPN localization for GRB990506
  51. GRB 970228: Redshift and properties of the host galaxy
  52. IPN localization of GRB990427
  53. GRB981220 VLBA observations
  54. GRB980425 Optical observations of exponential decline at late time
  55. GRB990321 REFINED IPN ANNULUS
  56. GRB990323 PRECISE IPN POSITION
  57. GRB990321 IPN TRIANGULATION
  58. GRB 990316 Optical Observations
  59. GRB 990316, Radio observations
  60. GRB 990316, Optical observations
  61. GRB990316, Optical observations
  62. GRB 990316 optical observations
  63. GRB990316: simultaneous optical observation
  64. ASM/IPN error box for GRB 990308 (BATSE #7457)
  65. GRB990308 not a new SGR
  66. GRB 990308a and GRB 990308b
  67. GRB990308 (Trig. 7457), optical observations
  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. Optical Observations of GRB990217
  74. GRB990123: Caltech STIS Photometry and Images
  75. GRB990123 observations
  76. GRB990123, Optical Observation
  77. GRB 990123: Discovery of the Probable Host Galaxy
  78. GRB 990123: Reduced HST Images
  79. For Immediate Posting to GCN - HST Data GRB 990123 Available
  80. GRB19990123 observations
  81. GRB 990123: BVRI standards in the field
  82. GRB 990123: Updated Keck Spectroscopy Results
  83. GRB981220, field photometry
  84. GRB 990123 NOT Spectrum Update
  85. GRB990123, Optical observation
  86. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  87. GRB 990123: Publicly available reduced HST images
  88. GRB990123, Upcoming HST Service Observations
  89. GRB 990123: New Constraints on Possible Foreground Galaxies
  90. GRB990123 Optical Observations
  91. GRB990123, Probability of gravitational lensing
  92. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  93. GRB 990123: Continued Radio Observations
  94. GRB990123, Preliminary Lens Search Results
  95. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  96. On the Lensing Interpretation of GRB 990123
  97. Search for Potential Images of GRB 990123
  98. Search for Potential Images of GRB 990123
  99. GRB990123, Optical BVRI Observations
  100. GRB 990123: near-infrared observations.

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