Skip to main content
Circulars over Kafka event name backfill. See news and announcements

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

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov