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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. GRB 990506, optical observations from +1 to +3 hours
  2. GRB 990506, optical observations
  3. GRB990506 Optical observations
  4. GRB990506 observation plan
  5. New IPN/RXTE error box for GRB990506
  6. IPN localization for GRB990506
  7. GRB 970228: Redshift and properties of the host galaxy
  8. IPN localization of GRB990427
  9. GRB981220 VLBA observations
  10. GRB980425 Optical observations of exponential decline at late time
  11. GRB990321 REFINED IPN ANNULUS
  12. GRB990323 PRECISE IPN POSITION
  13. GRB990321 IPN TRIANGULATION
  14. GRB 990316 Optical Observations
  15. GRB 990316, Radio observations
  16. GRB 990316, Optical observations
  17. GRB990316, Optical observations
  18. GRB 990316 optical observations
  19. GRB990316: simultaneous optical observation
  20. GRB990316 - Optical null results
  21. ASM/IPN error box for GRB 990308 (BATSE #7457)
  22. GRB990308 not a new SGR
  23. GRB 990308a and GRB 990308b
  24. GRB990308 (Trig. 7457), optical observations
  25. GRB990308, Possible new SGR~0209+70
  26. GRB981220, IPN localization
  27. GRB 981220, radio observations
  28. GRB 990123, Field Photometry
  29. GRB 990217 Optical Observations
  30. GRB 990217, radio observations
  31. BATSE Resumes Normal Operations
  32. BATSE Flight Anomaly
  33. GRB990217: BeppoSAX/GRBM data
  34. Optical Observations of GRB990217
  35. GRB990123: Caltech STIS Photometry and Images
  36. GRB990123 observations
  37. GRB990217 Optical observation
  38. GRB990217, WFC position
  39. GRB990123, Optical Observation
  40. GRB 990123: Discovery of the Probable Host Galaxy
  41. GRB 990123: Reduced HST Images
  42. For Immediate Posting to GCN - HST Data GRB 990123 Available
  43. GRB19990123 observations
  44. GRB 990123: BVRI standards in the field
  45. GRB 990123: Updated Keck Spectroscopy Results
  46. GRB981220, field photometry
  47. GRB 990123 NOT Spectrum Update
  48. GRB990123, Optical observation
  49. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  50. GRB 990123: Publicly available reduced HST images
  51. GRB990123, Upcoming HST Service Observations
  52. GRB990123, 15-GHz limits
  53. GRB 990123: New Constraints on Possible Foreground Galaxies
  54. GRB990123 Optical Observations
  55. GRB990123, Probability of gravitational lensing
  56. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  57. GRB 990123: Continued Radio Observations
  58. GRB990123, Preliminary Lens Search Results
  59. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  60. On the Lensing Interpretation of GRB 990123
  61. Search for Potential Images of GRB 990123
  62. Search for Potential Images of GRB 990123
  63. GRB990123, Optical BVRI Observations
  64. GRB 990123: near-infrared observations.
  65. GRB990123, OSSE observations
  66. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
  67. GRB990123: NIR Observation
  68. GRB990123, ASCA X-ray observation of afterglow
  69. "GRB 990123: New BV Observations"
  70. GRB 990123 Optical Follow-Up
  71. GRB 990123; Addendum to GCN 223
  72. GRB 990123: BATSE Observations
  73. GRB 990123 Keck Spectrum update
  74. GRB990123 IPN annulus
  75. GRB 990123 : Multiple and Distorted Images of the Host Galaxy?
  76. GRB990123 Optical Observations
  77. GRB 990123 Spectroscopic Redshifts
  78. GRB 990123: New Optical Observations, Decay Measure
  79. GRB 990123 Optical Follow-Up
  80. GRB 990123: Possible Gravitationally Lensed Burst?
  81. GRB990123, optical observation
  82. GRB 990123 optical observations
  83. GRB 990123: Pre-Burst Detection of an Apparent Host Galaxy
  84. GRB 990123 radio observations
  85. GRB 990123, new radio source
  86. GRB990123 optical observations
  87. GRB990123, Optical observation
  88. GRB 990123: Optical Decay Slope
  89. GRB 990123 r-band photometry
  90. GRB 990123 Optical Follow-up
  91. GRB990123, early optical counterpart detection
  92. GRB990123 Optical Observation
  93. GRB990123, BeppoSAX-NFI X-ray afterglow detection
  94. GRB990123, refined SAX-WFC position
  95. GRB 990123: Bright New Source, Possible Optical Transient
  96. GRB 990123, Radio observations
  97. GRB990123, BeppoSAX WFC detection and NFI planned follow-up
  98. SN 1999E & GRB 980919
  99. Possible identification of SN1999E with GRB980910
  100. Optical Observations of GRB 981220

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