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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 990510 Optical Observations
  2. GRB 990510, BVI photometry
  3. GRB 990510 optical observations
  4. GRB 990510: BeppoSAX/GRBM observations
  5. GRB990510 optical observations
  6. GRB990510
  7. GRB 990510 optical observations
  8. GRB 990510 optical observations
  9. Galactic extinction towards GRB 990510
  10. GRB990510: NFI X-ray source
  11. GRB 990510 optical observations
  12. IPN localization of GRB990510
  13. GRB 990506 Radio Observations
  14. GRB 990123, optical monitoring
  15. GRB 990506: BATSE Observations
  16. GRB 990506, optical observations
  17. GRB 990510: Final BeppoSAX-WFC Coordinates
  18. GRB 990506, Optical Observations
  19. GRB 990506 optical observations
  20. GRB 990506 optical observations
  21. GRB 990506, optical observations
  22. GRB990506 observation plan
  23. Refined IPN error box for GRB990506
  24. GRB 990506: Limits on the possible optical transient
  25. GRB 990506, armchair astronomy
  26. GRB 990506, optical observations from +1 to +3 hours
  27. GRB 990506, optical observations
  28. GRB990506 Optical observations
  29. GRB990506 observation plan
  30. New IPN/RXTE error box for GRB990506
  31. IPN localization for GRB990506
  32. GRB 970228: Redshift and properties of the host galaxy
  33. IPN localization of GRB990427
  34. GRB981220 VLBA observations
  35. GRB980425 Optical observations of exponential decline at late time
  36. GRB990321 REFINED IPN ANNULUS
  37. GRB990323 PRECISE IPN POSITION
  38. GRB990321 IPN TRIANGULATION
  39. GRB 990316 Optical Observations
  40. GRB 990316, Radio observations
  41. GRB 990316, Optical observations
  42. GRB990316, Optical observations
  43. GRB 990316 optical observations
  44. GRB990316: simultaneous optical observation
  45. GRB990316 - Optical null results
  46. ASM/IPN error box for GRB 990308 (BATSE #7457)
  47. GRB990308 not a new SGR
  48. GRB 990308a and GRB 990308b
  49. GRB990308 (Trig. 7457), optical observations
  50. GRB990308, Possible new SGR~0209+70
  51. GRB981220, IPN localization
  52. GRB 981220, radio observations
  53. GRB 990123, Field Photometry
  54. GRB 990217 Optical Observations
  55. GRB 990217, radio observations
  56. BATSE Resumes Normal Operations
  57. BATSE Flight Anomaly
  58. GRB990217: BeppoSAX/GRBM data
  59. Optical Observations of GRB990217
  60. GRB990123: Caltech STIS Photometry and Images
  61. GRB990123 observations
  62. GRB990217 Optical observation
  63. GRB990217, WFC position
  64. GRB990123, Optical Observation
  65. GRB 990123: Discovery of the Probable Host Galaxy
  66. GRB 990123: Reduced HST Images
  67. For Immediate Posting to GCN - HST Data GRB 990123 Available
  68. GRB19990123 observations
  69. GRB 990123: BVRI standards in the field
  70. GRB 990123: Updated Keck Spectroscopy Results
  71. GRB981220, field photometry
  72. GRB 990123 NOT Spectrum Update
  73. GRB990123, Optical observation
  74. GRB990123, is the "radio flare" due to an inhomogeneous medium?
  75. GRB 990123: Publicly available reduced HST images
  76. GRB990123, Upcoming HST Service Observations
  77. GRB990123, 15-GHz limits
  78. GRB 990123: New Constraints on Possible Foreground Galaxies
  79. GRB990123 Optical Observations
  80. GRB990123, Probability of gravitational lensing
  81. GRB 990123: Detection of the IR Transient, and the Light Curve Fits
  82. GRB 990123: Continued Radio Observations
  83. GRB990123, Preliminary Lens Search Results
  84. GRB 990123: Correction to GCN 230 - C.A. Young added to author list
  85. On the Lensing Interpretation of GRB 990123
  86. Search for Potential Images of GRB 990123
  87. Search for Potential Images of GRB 990123
  88. GRB990123, Optical BVRI Observations
  89. GRB 990123: near-infrared observations.
  90. GRB990123, OSSE observations
  91. GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
  92. GRB990123: NIR Observation
  93. GRB990123, ASCA X-ray observation of afterglow
  94. "GRB 990123: New BV Observations"
  95. GRB 990123 Optical Follow-Up
  96. GRB 990123; Addendum to GCN 223
  97. GRB 990123: BATSE Observations
  98. GRB 990123 Keck Spectrum update
  99. GRB990123 IPN annulus
  100. GRB 990123 : Multiple and Distorted Images of the Host Galaxy?

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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