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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 VLBA observations
  2. GRB980425 Optical observations of exponential decline at late time
  3. GRB990321 REFINED IPN ANNULUS
  4. GRB990323 PRECISE IPN POSITION
  5. GRB990321 IPN TRIANGULATION
  6. GRB 990316 Optical Observations
  7. GRB 990316, Radio observations
  8. GRB 990316, Optical observations
  9. GRB990316, Optical observations
  10. GRB 990316 optical observations
  11. GRB990316: simultaneous optical observation
  12. GRB990316 - Optical null results
  13. ASM/IPN error box for GRB 990308 (BATSE #7457)
  14. GRB990308 not a new SGR
  15. GRB 990308a and GRB 990308b
  16. GRB990308 (Trig. 7457), optical observations
  17. GRB990308, Possible new SGR~0209+70
  18. GRB981220, IPN localization
  19. GRB 981220, radio observations
  20. GRB 990123, Field Photometry
  21. GRB 990217 Optical Observations
  22. GRB 990217, radio observations
  23. BATSE Resumes Normal Operations
  24. BATSE Flight Anomaly
  25. GRB990217: BeppoSAX/GRBM data
  26. Optical Observations of GRB990217
  27. GRB990123: Caltech STIS Photometry and Images
  28. GRB990123 observations
  29. GRB990217 Optical observation
  30. GRB990217, WFC position
  31. GRB990123, Optical Observation
  32. GRB 990123: Discovery of the Probable Host Galaxy
  33. GRB 990123: Reduced HST Images
  34. For Immediate Posting to GCN - HST Data GRB 990123 Available
  35. GRB19990123 observations
  36. GRB 990123: BVRI standards in the field
  37. GRB 990123: Updated Keck Spectroscopy Results
  38. GRB981220, field photometry
  39. GRB 990123 NOT Spectrum Update
  40. GRB990123, Optical observation
  41. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  42. GRB 990123: Publicly available reduced HST images
  43. GRB990123, Upcoming HST Service Observations
  44. GRB990123, 15-GHz limits
  45. GRB 990123: New Constraints on Possible Foreground Galaxies
  46. GRB990123 Optical Observations
  47. GRB990123, Probability of gravitational lensing
  48. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  49. GRB 990123: Continued Radio Observations
  50. GRB990123, Preliminary Lens Search Results
  51. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  52. On the Lensing Interpretation of GRB 990123
  53. Search for Potential Images of GRB 990123
  54. Search for Potential Images of GRB 990123
  55. GRB990123, Optical BVRI Observations
  56. GRB 990123: near-infrared observations.
  57. GRB990123, OSSE observations
  58. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
  59. GRB990123: NIR Observation
  60. GRB990123, ASCA X-ray observation of afterglow
  61. "GRB 990123: New BV Observations"
  62. GRB 990123 Optical Follow-Up
  63. GRB 990123; Addendum to GCN 223
  64. GRB 990123: BATSE Observations
  65. GRB 990123 Keck Spectrum update
  66. GRB990123 IPN annulus
  67. GRB 990123 : Multiple and Distorted Images of the Host Galaxy?
  68. GRB990123 Optical Observations
  69. GRB 990123 Spectroscopic Redshifts
  70. GRB 990123: New Optical Observations, Decay Measure
  71. GRB 990123 Optical Follow-Up
  72. GRB 990123: Possible Gravitationally Lensed Burst?
  73. GRB990123, optical observation
  74. GRB 990123 optical observations
  75. GRB 990123: Pre-Burst Detection of an Apparent Host Galaxy
  76. GRB 990123 radio observations
  77. GRB 990123, new radio source
  78. GRB990123 optical observations
  79. GRB990123, Optical observation
  80. GRB 990123: Optical Decay Slope
  81. GRB 990123 r-band photometry
  82. GRB 990123 Optical Follow-up
  83. GRB990123, early optical counterpart detection
  84. GRB990123 Optical Observation
  85. GRB990123, BeppoSAX-NFI X-ray afterglow detection
  86. GRB990123, refined SAX-WFC position
  87. GRB 990123: Bright New Source, Possible Optical Transient
  88. GRB 990123, Radio observations
  89. GRB990123, BeppoSAX WFC detection and NFI planned follow-up
  90. SN 1999E & GRB 980919
  91. Possible identification of SN1999E with GRB980910
  92. Optical Observations of GRB 981220
  93. GRB 981226: radio variable
  94. GRB981220
  95. GRB981220, Correction to GCN 179
  96. GRB981220, Optical Observations
  97. GRB 981220 Optical observations
  98. GRB 981226 Optical Observations
  99. GRB 980613: Spectroscopy of the host galaxy
  100. GRB981226, sub-millimeter observations

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