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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"

44541 results found.

  1. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  2. Optical report on X-ray/GRB transient
  3. radio detection of X-ray/GRB transient
  4. BeppoSAX: A new fast X-ray transient
  5. GRB 990510: optical observations
  6. GRB990510: photometric and spectroscopic observations with the VLT
  7. GRB 990510: optical linear polarization
  8. GRB 990510: optical observations
  9. GRB990510, VI observations
  10. GRB 990506 R band observations
  11. GRB990510: X-ray afterglow
  12. GRB 990510: optical observation
  13. VLT spectrum of GRB990510
  14. GRB 990510: Broad Band Break
  15. GRB 990510: BATSE Observations
  16. GRB990510: optical observation
  17. GRB 990510 Optical Observations
  18. GRB 990510, BVI photometry
  19. GRB 990510 optical observations
  20. GRB 990510: BeppoSAX/GRBM observations
  21. GRB990510 optical observations
  22. GRB990510
  23. GRB 990510 optical observations
  24. GRB 990510 optical observations
  25. Galactic extinction towards GRB 990510
  26. GRB990510: NFI X-ray source
  27. GRB 990510 optical observations
  28. IPN localization of GRB990510
  29. GRB 990506 Radio Observations
  30. GRB 990123, optical monitoring
  31. GRB 990506: BATSE Observations
  32. GRB 990506, optical observations
  33. GRB 990510: Final BeppoSAX-WFC Coordinates
  34. GRB 990506, Optical Observations
  35. GRB 990506 optical observations
  36. GRB 990506 optical observations
  37. GRB 990506, optical observations
  38. GRB990506 observation plan
  39. Refined IPN error box for GRB990506
  40. GRB 990506: Limits on the possible optical transient
  41. GRB 990506, armchair astronomy
  42. GRB 990506, optical observations from +1 to +3 hours
  43. GRB 990506, optical observations
  44. GRB990506 Optical observations
  45. GRB990506 observation plan
  46. New IPN/RXTE error box for GRB990506
  47. IPN localization for GRB990506
  48. GRB 970228: Redshift and properties of the host galaxy
  49. IPN localization of GRB990427
  50. GRB981220 VLBA observations
  51. GRB980425 Optical observations of exponential decline at late time
  52. GRB990321 REFINED IPN ANNULUS
  53. GRB990323 PRECISE IPN POSITION
  54. GRB990321 IPN TRIANGULATION
  55. GRB 990316 Optical Observations
  56. GRB 990316, Radio observations
  57. GRB 990316, Optical observations
  58. GRB990316, Optical observations
  59. GRB 990316 optical observations
  60. GRB990316: simultaneous optical observation
  61. GRB990316 - Optical null results
  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. GRB990308, Possible new SGR~0209+70
  67. GRB981220, IPN localization
  68. GRB 981220, radio observations
  69. GRB 990123, Field Photometry
  70. GRB 990217 Optical Observations
  71. GRB 990217, radio observations
  72. BATSE Resumes Normal Operations
  73. BATSE Flight Anomaly
  74. GRB990217: BeppoSAX/GRBM data
  75. Optical Observations of GRB990217
  76. GRB990123: Caltech STIS Photometry and Images
  77. GRB990123 observations
  78. GRB990217 Optical observation
  79. GRB990217, WFC position
  80. GRB990123, Optical Observation
  81. GRB 990123: Discovery of the Probable Host Galaxy
  82. GRB 990123: Reduced HST Images
  83. For Immediate Posting to GCN - HST Data GRB 990123 Available
  84. GRB19990123 observations
  85. GRB 990123: BVRI standards in the field
  86. GRB 990123: Updated Keck Spectroscopy Results
  87. GRB981220, field photometry
  88. GRB 990123 NOT Spectrum Update
  89. GRB990123, Optical observation
  90. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  91. GRB 990123: Publicly available reduced HST images
  92. GRB990123, Upcoming HST Service Observations
  93. GRB990123, 15-GHz limits
  94. GRB 990123: New Constraints on Possible Foreground Galaxies
  95. GRB990123 Optical Observations
  96. GRB990123, Probability of gravitational lensing
  97. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  98. GRB 990123: Continued Radio Observations
  99. GRB990123, Preliminary Lens Search Results
  100. GRB 990123: Correction to GCN 230 - C.A. Young added to author list

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