Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
Retirement of GCN Classic VOEvent Brokers. 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. GRB 990704, optical observations
  2. GRB990704
  3. GRB990705: Intriguing Positional Coincidences
  4. GRB990704
  5. Refined BeppoSAX-WFC position of GRB990704: Errata Corrige
  6. GRB990704, optical observations
  7. GRB990704: possible X-ray afterglow
  8. Identification of a possible optical counterpart for GRB990704
  9. GRB990704
  10. Refined BeppoSAX-WFC position of GRB990704
  11. GRB990704: BeppoSAX detection
  12. BeppoSAX NFI Observation of GRB990627 X-ray afterglow
  13. Optical Observations of GRB990627
  14. GRB 990627, radio observations
  15. GRB990627: BeppoSAX-WFC final location
  16. BeppoSAX: GRB990625
  17. Late-time HST/STIS Observation of GRB 990123
  18. GRB 990506 - clarification to GCN 352
  19. GRB 990506 - Optical Observations
  20. Optical Observations of GRB 990506
  21. GRB 990506 Radio Transient
  22. GRB990527 Optical Observations
  23. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  24. IPN error box for GRB990527
  25. Late Afterglows of GRBs 990510, 990123
  26. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  27. X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
  28. X-ray/GRB 1SAX J0835.9+5118, Optical Observations
  29. GRB 990506 optical observation
  30. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  31. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  32. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  33. X-ray/GRB 1SAX J0835.9+5118, Optical Observation
  34. radio observations of X-ray/GRB transient field
  35. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  36. Optical report on X-ray/GRB transient
  37. radio detection of X-ray/GRB transient
  38. BeppoSAX: A new fast X-ray transient
  39. GRB 990510: optical observations
  40. GRB990510: photometric and spectroscopic observations with the VLT
  41. GRB 990510: optical linear polarization
  42. GRB 990510: optical observations
  43. GRB990510, VI observations
  44. GRB 990506 R band observations
  45. GRB990510: X-ray afterglow
  46. GRB 990510: optical observation
  47. VLT spectrum of GRB990510
  48. GRB 990510: Broad Band Break
  49. GRB 990510: BATSE Observations
  50. GRB990510: optical observation
  51. GRB 990510 Optical Observations
  52. GRB 990510, BVI photometry
  53. GRB 990510 optical observations
  54. GRB 990510: BeppoSAX/GRBM observations
  55. GRB990510 optical observations
  56. GRB990510
  57. GRB 990510 optical observations
  58. GRB 990510 optical observations
  59. Galactic extinction towards GRB 990510
  60. GRB990510: NFI X-ray source
  61. GRB 990510 optical observations
  62. IPN localization of GRB990510
  63. GRB 990506 Radio Observations
  64. GRB 990123, optical monitoring
  65. GRB 990506: BATSE Observations
  66. GRB 990506, optical observations
  67. GRB 990510: Final BeppoSAX-WFC Coordinates
  68. GRB 990506, Optical Observations
  69. GRB 990506 optical observations
  70. GRB 990506 optical observations
  71. GRB 990506, optical observations
  72. GRB990506 observation plan
  73. Refined IPN error box for GRB990506
  74. GRB 990506: Limits on the possible optical transient
  75. GRB 990506, armchair astronomy
  76. GRB 990506, optical observations from +1 to +3 hours
  77. GRB 990506, optical observations
  78. GRB990506 Optical observations
  79. GRB990506 observation plan
  80. New IPN/RXTE error box for GRB990506
  81. IPN localization for GRB990506
  82. GRB 970228: Redshift and properties of the host galaxy
  83. IPN localization of GRB990427
  84. GRB981220 VLBA observations
  85. GRB980425 Optical observations of exponential decline at late time
  86. GRB990321 REFINED IPN ANNULUS
  87. GRB990323 PRECISE IPN POSITION
  88. GRB990321 IPN TRIANGULATION
  89. GRB 990316 Optical Observations
  90. GRB 990316, Radio observations
  91. GRB 990316, Optical observations
  92. GRB990316, Optical observations
  93. GRB 990316 optical observations
  94. GRB990316: simultaneous optical observation
  95. GRB990316 - Optical null results
  96. ASM/IPN error box for GRB 990308 (BATSE #7457)
  97. GRB990308 not a new SGR
  98. GRB 990308a and GRB 990308b
  99. GRB990308 (Trig. 7457), optical observations
  100. GRB990308, Possible new SGR~0209+70

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