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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. GRB981220, IPN localization
  2. GRB 981220, radio observations
  3. GRB 990123, Field Photometry
  4. GRB 990217 Optical Observations
  5. GRB 990217, radio observations
  6. BATSE Resumes Normal Operations
  7. BATSE Flight Anomaly
  8. GRB990217: BeppoSAX/GRBM data
  9. Optical Observations of GRB990217
  10. GRB990123: Caltech STIS Photometry and Images
  11. GRB990123 observations
  12. GRB990217 Optical observation
  13. GRB990217, WFC position
  14. GRB990123, Optical Observation
  15. GRB 990123: Discovery of the Probable Host Galaxy
  16. GRB 990123: Reduced HST Images
  17. For Immediate Posting to GCN - HST Data GRB 990123 Available
  18. GRB19990123 observations
  19. GRB 990123: BVRI standards in the field
  20. GRB 990123: Updated Keck Spectroscopy Results
  21. GRB981220, field photometry
  22. GRB 990123 NOT Spectrum Update
  23. GRB990123, Optical observation
  24. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  25. GRB 990123: Publicly available reduced HST images
  26. GRB990123, Upcoming HST Service Observations
  27. GRB990123, 15-GHz limits
  28. GRB 990123: New Constraints on Possible Foreground Galaxies
  29. GRB990123 Optical Observations
  30. GRB990123, Probability of gravitational lensing
  31. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  32. GRB 990123: Continued Radio Observations
  33. GRB990123, Preliminary Lens Search Results
  34. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  35. On the Lensing Interpretation of GRB 990123
  36. Search for Potential Images of GRB 990123
  37. Search for Potential Images of GRB 990123
  38. GRB990123, Optical BVRI Observations
  39. GRB 990123: near-infrared observations.
  40. GRB990123, OSSE observations
  41. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
  42. GRB990123: NIR Observation
  43. GRB990123, ASCA X-ray observation of afterglow
  44. "GRB 990123: New BV Observations"
  45. GRB 990123 Optical Follow-Up
  46. GRB 990123; Addendum to GCN 223
  47. GRB 990123: BATSE Observations
  48. GRB 990123 Keck Spectrum update
  49. GRB990123 IPN annulus
  50. GRB 990123 : Multiple and Distorted Images of the Host Galaxy?
  51. GRB990123 Optical Observations
  52. GRB 990123 Spectroscopic Redshifts
  53. GRB 990123: New Optical Observations, Decay Measure
  54. GRB 990123 Optical Follow-Up
  55. GRB 990123: Possible Gravitationally Lensed Burst?
  56. GRB990123, optical observation
  57. GRB 990123 optical observations
  58. GRB 990123: Pre-Burst Detection of an Apparent Host Galaxy
  59. GRB 990123 radio observations
  60. GRB 990123, new radio source
  61. GRB990123 optical observations
  62. GRB990123, Optical observation
  63. GRB 990123: Optical Decay Slope
  64. GRB 990123 r-band photometry
  65. GRB 990123 Optical Follow-up
  66. GRB990123, early optical counterpart detection
  67. GRB990123 Optical Observation
  68. GRB990123, BeppoSAX-NFI X-ray afterglow detection
  69. GRB990123, refined SAX-WFC position
  70. GRB 990123: Bright New Source, Possible Optical Transient
  71. GRB 990123, Radio observations
  72. GRB990123, BeppoSAX WFC detection and NFI planned follow-up
  73. SN 1999E & GRB 980919
  74. Possible identification of SN1999E with GRB980910
  75. Optical Observations of GRB 981220
  76. GRB 981226: radio variable
  77. GRB981220
  78. GRB981220, Correction to GCN 179
  79. GRB981220, Optical Observations
  80. GRB 981220 Optical observations
  81. GRB 981226 Optical Observations
  82. GRB 980613: Spectroscopy of the host galaxy
  83. GRB981226, sub-millimeter observations
  84. GRB981220, sub-millimeter observations
  85. GRB 981220 and GRB 981226, optical observations
  86. GRB981226 Optical Observations
  87. GRB981226 BeppoSAX follow up
  88. GRB 981226 radio observations
  89. GRB 981226
  90. GRB 981226 optical observations
  91. radio observations of GRB 981226
  92. GRB981220 B, R and I band observations
  93. GRB981226, BeppoSAX-NFI follow-up
  94. Optical Observations of GRB981226
  95. GRB 981220:Optical Observations
  96. GRB 981220 optical R and I observations
  97. GRB981226, BeppoSAX Christmas GRB
  98. GRB 981226 - Infrared Observations
  99. GRB 981226 optical observations
  100. GRB 981220

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