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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"

35983 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. GRB 990510 optical observations
  31. IPN localization of GRB990510
  32. GRB 990506 Radio Observations
  33. GRB 990123, optical monitoring
  34. GRB 990506: BATSE Observations
  35. GRB 990506, optical observations
  36. GRB 990510: Final BeppoSAX-WFC Coordinates
  37. GRB 990506, Optical Observations
  38. GRB 990506 optical observations
  39. GRB 990506 optical observations
  40. GRB 990506, optical observations
  41. GRB990506 observation plan
  42. Refined IPN error box for GRB990506
  43. GRB 990506: Limits on the possible optical transient
  44. GRB 990506, armchair astronomy
  45. GRB 990506, optical observations from +1 to +3 hours
  46. GRB 990506, optical observations
  47. GRB990506 observation plan
  48. New IPN/RXTE error box for GRB990506
  49. IPN localization for GRB990506
  50. GRB 970228: Redshift and properties of the host galaxy
  51. IPN localization of GRB990427
  52. GRB981220 VLBA observations
  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. ASM/IPN error box for GRB 990308 (BATSE #7457)
  63. GRB990308 not a new SGR
  64. GRB 990308a and GRB 990308b
  65. GRB990308 (Trig. 7457), optical observations
  66. GRB981220, IPN localization
  67. GRB 981220, radio observations
  68. GRB 990123, Field Photometry
  69. GRB 990217 Optical Observations
  70. GRB 990217, radio observations
  71. Optical Observations of GRB990217
  72. GRB990123: Caltech STIS Photometry and Images
  73. GRB990123 observations
  74. GRB990123, Optical Observation
  75. GRB 990123: Discovery of the Probable Host Galaxy
  76. GRB 990123: Reduced HST Images
  77. For Immediate Posting to GCN - HST Data GRB 990123 Available
  78. GRB19990123 observations
  79. GRB 990123: BVRI standards in the field
  80. GRB 990123: Updated Keck Spectroscopy Results
  81. GRB981220, field photometry
  82. GRB 990123 NOT Spectrum Update
  83. GRB990123, Optical observation
  84. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  85. GRB 990123: Publicly available reduced HST images
  86. GRB990123, Upcoming HST Service Observations
  87. GRB 990123: New Constraints on Possible Foreground Galaxies
  88. GRB990123 Optical Observations
  89. GRB990123, Probability of gravitational lensing
  90. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  91. GRB 990123: Continued Radio Observations
  92. GRB990123, Preliminary Lens Search Results
  93. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  94. On the Lensing Interpretation of GRB 990123
  95. Search for Potential Images of GRB 990123
  96. Search for Potential Images of GRB 990123
  97. GRB990123, Optical BVRI Observations
  98. GRB 990123: near-infrared observations.
  99. GRB990123, OSSE observations
  100. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW

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