Skip to main content
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 070810: enhanced Swift-XRT position
  2. GRB 070810: Swift/UVOT Optical Counterpart
  3. GRB 070810: ROTSE-III Detection of Optical Counterpart
  4. GRB 070810: Swift detection of a burst
  5. GRB 070809, Swift-BAT refined analysis
  6. GRB 070809: Optical Pre-imaging from Palomar
  7. GRB 070808: Swift/UVOT upper limits
  8. GRB 070809: ROTSE-III Optical Limits
  9. GRB 070809: Swift detection of a short burst
  10. GRB 070808 : Faulkes Telescope South Observations
  11. GCN Swift XRT update position notices and enhanced position circulars
  12. GRB 070808: Swift XRT refined analysis
  13. GRB 070808, Swift-BAT refined analysis
  14. GRB 070808: OPTIMA-Burst optical upper limit
  15. GRB 070808: Xinglong TNT optical Upper Limit
  16. GRB070808: Optical observations with KANATA
  17. GRB070808 - SDSS Pre-Burst Observations
  18. GRB 070808: ROTSE-III Optical Limits
  19. GRB 070808: Swift detection of a burst
  20. GRB061121A: PROMPT Observations
  21. GRB070805 XRT and UVOT afterglow candidate
  22. Swift trigger on 4U 1700-377 while star tracker loss-of-lock
  23. GRB070612A: Radio upper limit from GMRT
  24. GRB 070721B: correct afterglow position
  25. Swift/UVOT observations of GRB070805
  26. GRB 070805, Swift-BAT refined analysis
  27. GRB 070805: Swift XRT initial analysis.
  28. GRB 070805: Swift/UVOT initial analysis
  29. GRB 070805: Swift detection of a burst
  30. UVOT observations of SAXJ1810.8-2609
  31. Swift detection of a outburst from SAX J1810.8-2609
  32. VLA non-detection of GRB 070721B
  33. GRB 070802: REM optical observations
  34. GRB 070724B: Swift-XRT afterglow confirmation
  35. GRB 070802: Swift-XRT refined analysis
  36. GRB070802: Swift/UVOT upper limits
  37. GRB 070802: Confirmation of the optical afterglow
  38. GRB 070802, Swift-BAT refined analysis
  39. GRB 070802: VLT redshift
  40. GRB 070802: refined Swift XRT position
  41. GRB 070802: V-band detection of the candidate afterglow
  42. GRB 070802: LCO I-band candidate
  43. GRB 070802: GROND J band candidate
  44. GRB 070802: LCO optical observations
  45. GRB 070802: Swift detection of a burst
  46. GRB 070731, Swift-BAT refined analysis
  47. Konus-A observation of GRB 070729
  48. Swift/UVOT detection of GRB070714B
  49. AGILE-ACS position for the SGR 1806-20 July 27 burst
  50. GRB 070724B: pseudo-z ~ 1.10 from prompt emission spectrum
  51. GRB 070729: LCO optical imaging
  52. VLA upper limit on short hard burst GRB 070714B
  53. Intense burst from SGR 1806-20 detected on July 27
  54. GRB070729: Swift/UVOT upper limits
  55. GRB 070729: Swift-XRT refined analysis
  56. GRB 070729, Swift-BAT refined analysis
  57. GRB 070729: Magellan NIR Observations
  58. GRB 070724B: P60 Observations
  59. GRB 070729: Swift detection of a short hard burst
  60. GRB 070724B: Swift/UVOT Upper limits
  61. GRB070721A: Swift/UVOT Detection of a Weak Afterglow
  62. GRB 070724B: Swift-XRT afterglow likely candidate
  63. GRB 070721A: optical observations
  64. GRB 070724A: further VLT observations
  65. GRB 070724B: Suzaku WAM observation of the prompt emission
  66. Konus-Wind observation of GRB 070724B
  67. GRB 070724B: Analysis of AGILE gamma-ray data
  68. GRB 070724B: Swift-XRT afterglow candidates
  69. GRB 070724b: First Gamma Ray Burst Localization by SuperAGILE onboard
  70. Four radio sources in Swift-XRT error box of GRB 070724
  71. GRB 070724: optical observations
  72. GRB070724: Host galaxy redshift
  73. GRB 070724: P60 and Gemini Observations
  74. GRB 060814 - Keck host detection and redshift
  75. GRB 070724: IR observations
  76. GRB 070724: Closer association with DSS source
  77. Swift/UVOT refined analysis of GRB070724
  78. GRB 070724: Swift-XRT Team refined analysis
  79. GRB 070724: Pre-Imaging Shows a Source in the XRT Error Circle
  80. Short-Hard GRB070714B: PROMPT Observations
  81. GRB 070724, Swift-BAT refined analysis of a short burst
  82. GRB 070721B: further observations and analysis
  83. GRB 070724: Swift detection of a burst
  84. GRB 070326: Detection of first burst from BAT Slew Survey (BATSS)
  85. GRB 070714B: Keck observations
  86. GRB 070721B: optical observations and proposed redshift
  87. Swift/UVOT observations of GRB070721B optical afterglow.
  88. GRB 070721B, Further Swift-BAT refined analysis
  89. Swift/UVOT Observations of GRB070721A
  90. GRB 070721B : Faulkes Telescope South observations
  91. GRB 070721B: Swift-XRT refined analysis
  92. GRB 070721A : Faulkes Telescope South optical limit
  93. GRB 070721A: Swift/XRT refined analysis
  94. GRB 070721B, Swift-BAT refined analysis
  95. GRB 070721A, Swift-BAT refined analysis
  96. GRB070721B: A bright UVOT candidate
  97. GRB 070721B: Swift detection of a burst
  98. GRB 070721: Swift detection of a possible burst
  99. GRB 070714B: Swift/BAT and Suzaku/WAM joint spectral analysis
  100. GRB 070714B : Suzaku WAM observation of the prompt emission

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