Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
Due to the lapse in federal government funding, NASA is not updating this website. See the Operations FAQ for GCN impacts.
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  2. GRB011130 (=XRF011130), Optical Observations
  3. XRF011130: NEAT Optical Observations
  4. GRB011130 (=XRF011130): Revised Localization of an X-ray
  5. GRB001109, Radio Monitoring
  6. GRB 011121: Errata URL
  7. GRB 011121
  8. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  9. GRB 011121: J-band observations
  10. GRB 011121: NIR observations, host galaxy?
  11. GRB010921 - Milagro GeV/TeV Observations
  12. GRB 011121: HST Scheduled
  13. GRB011121: fainter still
  14. Correction: GCN1157 (GRB 011121)
  15. GRB011121: UBRI Observations
  16. GRB011121
  17. GRB 011121: Radio Observations
  18. GRB 011121 J-Band Astrometry
  19. GRB011121: continued decay
  20. GRB 011121: Detection of Bright IR Counterpart
  21. GRB011121: possible redshift, continued decay
  22. GRB011121: fading behavior
  23. GRB011121: possible optical counterpart
  24. GRB011121: BeppoSAX-WFC refined positions
  25. IPN triangulation of GRB011121
  26. BEPPOSAX GRB011121
  27. GRB 011030: TNG K-band observation
  28. XRF011030: J and K band observations
  29. GRB011030, optical observation
  30. XRF011030: Chandra Observations
  31. GRB 011030: K-band observations
  32. GRB011030: Z-band observations
  33. GRB 011030 R band observations
  34. GRB 011030 I-band Observation
  35. The X-ray Flash 011030 ('GRB 011030')
  36. Non-triggered burst 011030 ("GRB 011030")
  37. The Radio Afterglow from the X-ray Rich GRB 011030
  38. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  39. GRB 970828: HST Observations of the Host Galaxy
  40. GRB 000131: HST Detection of the Host Galaxy
  41. GRB 970828: HST Observations of the Host Galaxy
  42. GRB010921, optical observation
  43. GRB 011019 optical observation
  44. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  45. GRB011019: Subaru Optical Observations
  46. GRB 011030 I-band Observations
  47. GRB 011030 K-band Observations
  48. GRB010921, optical observations
  49. GRB 011030, WSRT radio observations
  50. GRB011030 - further refinement WFC position
  51. GRB 011030, Radio observations
  52. GRB011030: radio search
  53. GRB 011030, R-band observations
  54. X-ray rich GRB011030: BeppoSAX refined positions
  55. BeppoSAX ALERT: Possible X-ray rich GRB011030
  56. GRB 010921: Possible supernova component
  57. GRB011019: NEAT Optical Observations
  58. GRB011019: ROTSE-III optical observations
  59. GRB010921, optical observation at early time
  60. GRB 010921, I-band observations
  61. GRB011019: Optical observations
  62. GRB011019, optical observations -- correction
  63. GRB011019, optical observations
  64. GRB011019: A Faint, X-ray Rich GRB localized by HETE
  65. GRB010921: Spectroscopy of the Host Galaxy
  66. GRB 010921: The afterglow of HETE #1761
  67. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  68. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  69. GRB010923 as seen by BeppoSAX GRBM
  70. GRB010928(=H1770): Localization of a Long GRB by HETE
  71. GRB010923(=H1764): A Short Duration GRB Detected by HETE
  72. GRB010921, negative optical observations
  73. GRB010921 field photometry
  74. GRB010921 Optical Observations
  75. GRB 010921 DPOSS Images Available
  76. IPN triangulation of GRB010921 (=H1761)
  77. H1761: A Bright GRB Detected by HETE
  78. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  79. HETE Trigger #1760 (GRB 010920B?): a new optical source
  80. HETE Trigger #1759 (GRB 010920?) optical observations
  81. GRB001109, Host Galaxy Astrometry
  82. GRB000926, Host Galaxy Observations
  83. GRB001109, Host Galaxy Spectroscopic Observations
  84. Probable SGR or Short Duration GRB Detected by HETE
  85. GRB000926 Host Galaxy Observations
  86. GRB 010222: HST observations -- host galaxy and late-time decay
  87. BeppoSAX/GRBM detection of GRB 010801
  88. GCN and HETE status
  89. Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
  90. BeppoSAX/GRBM detection of GRB010728
  91. GRB 010222 - WHT BVRI images
  92. SGR1900+14 burst seen by HETE: BeppoSAX data
  93. GRB 010629 Optical Observations
  94. GRB010629: Optical Observations
  95. SGR1900+14: High Fluence Burst Localized by HETE
  96. GRB010629, optical observations
  97. IPN triangulation of GRB010629
  98. GRB010629: A Burst Localized by HETE
  99. SGR1900+14: Second Burst Localized by HETE
  100. SGR1900+14: A Burst Localized by HETE

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