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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 990123: Discovery of the Probable Host Galaxy
  2. GRB 990123: Reduced HST Images
  3. For Immediate Posting to GCN - HST Data GRB 990123 Available
  4. GRB19990123 observations
  5. GRB 990123: BVRI standards in the field
  6. GRB 990123: Updated Keck Spectroscopy Results
  7. GRB981220, field photometry
  8. GRB 990123 NOT Spectrum Update
  9. GRB990123, Optical observation
  10. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  11. GRB 990123: Publicly available reduced HST images
  12. GRB990123, Upcoming HST Service Observations
  13. GRB990123, 15-GHz limits
  14. GRB 990123: New Constraints on Possible Foreground Galaxies
  15. GRB990123 Optical Observations
  16. GRB990123, Probability of gravitational lensing
  17. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  18. GRB 990123: Continued Radio Observations
  19. GRB990123, Preliminary Lens Search Results
  20. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  21. On the Lensing Interpretation of GRB 990123
  22. Search for Potential Images of GRB 990123
  23. Search for Potential Images of GRB 990123
  24. GRB990123, Optical BVRI Observations
  25. GRB 990123: near-infrared observations.
  26. GRB990123, OSSE observations
  27. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
  28. GRB990123: NIR Observation
  29. GRB990123, ASCA X-ray observation of afterglow
  30. "GRB 990123: New BV Observations"
  31. GRB 990123 Optical Follow-Up
  32. GRB 990123; Addendum to GCN 223
  33. GRB 990123: BATSE Observations
  34. GRB 990123 Keck Spectrum update
  35. GRB990123 IPN annulus
  36. GRB 990123 : Multiple and Distorted Images of the Host Galaxy?
  37. GRB990123 Optical Observations
  38. GRB 990123 Spectroscopic Redshifts
  39. GRB 990123: New Optical Observations, Decay Measure
  40. GRB 990123 Optical Follow-Up
  41. GRB 990123: Possible Gravitationally Lensed Burst?
  42. GRB990123, optical observation
  43. GRB 990123 optical observations
  44. GRB 990123: Pre-Burst Detection of an Apparent Host Galaxy
  45. GRB 990123 radio observations
  46. GRB 990123, new radio source
  47. GRB990123 optical observations
  48. GRB990123, Optical observation
  49. GRB 990123: Optical Decay Slope
  50. GRB 990123 r-band photometry
  51. GRB 990123 Optical Follow-up
  52. GRB990123, early optical counterpart detection
  53. GRB990123 Optical Observation
  54. GRB990123, BeppoSAX-NFI X-ray afterglow detection
  55. GRB990123, refined SAX-WFC position
  56. GRB 990123: Bright New Source, Possible Optical Transient
  57. GRB 990123, Radio observations
  58. GRB990123, BeppoSAX WFC detection and NFI planned follow-up
  59. SN 1999E & GRB 980919
  60. Possible identification of SN1999E with GRB980910
  61. Optical Observations of GRB 981220
  62. GRB 981226: radio variable
  63. GRB981220
  64. GRB981220, Correction to GCN 179
  65. GRB981220, Optical Observations
  66. GRB 981220 Optical observations
  67. GRB 981226 Optical Observations
  68. GRB 980613: Spectroscopy of the host galaxy
  69. GRB981226, sub-millimeter observations
  70. GRB981220, sub-millimeter observations
  71. GRB 981220 and GRB 981226, optical observations
  72. GRB981226 Optical Observations
  73. GRB981226 BeppoSAX follow up
  74. GRB 981226 radio observations
  75. GRB 981226
  76. GRB 981226 optical observations
  77. radio observations of GRB 981226
  78. GRB981220 B, R and I band observations
  79. GRB981226, BeppoSAX-NFI follow-up
  80. Optical Observations of GRB981226
  81. GRB 981220:Optical Observations
  82. GRB 981220 optical R and I observations
  83. GRB981226, BeppoSAX Christmas GRB
  84. GRB 981226 - Infrared Observations
  85. GRB 981226 optical observations
  86. GRB 981220
  87. GRB 981220, radio observations
  88. GRB981226 Optical Observation
  89. GRB 981220, radio observations
  90. GRB 981220: BeppoSAX/GRBM results
  91. GRB981220 I-band Observations
  92. GRB981220 Optical Observations
  93. GRB 981220
  94. GRB 981220 Optical Observations
  95. GRB 981220, optical observations
  96. GRB 980326/Host Galaxy
  97. GRB981220 IPN error box
  98. GRB 981220: RXTE/ASM and BeppoSAX/GRBM results
  99. BeppoSAX NFI Observation of GRB980425
  100. GRB980329 R,I flux calibration and R,I,K upper limits

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