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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"

44649 results found.

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

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