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').
  1. short/hard GRB 050202, optical observations
  2. GRB050209: REM optical observations
  3. GRB 050209 I-band observation
  4. GRB 050209 Optical observations
  5. GRB050209: P60 Optical Observations
  6. GRB050209 (=U11568): A Long GRB Detected by HETE
  7. GRB 050209: Optical observation
  8. GRB 050128: Radio observations
  9. Further analysis of the short Swift-BAT GRB 050202
  10. GRB 050202: Second epoch radio observations
  11. GRB 050129: Optical observations
  12. GRB050202: Radio Observations
  13. GRB 050202: Optical observations with LCO40
  14. GRB 050202: Short burst detected by Swift-BAT
  15. GRB 050128 Optical observation with REM
  16. GRB 050129: a weak long GRB detected with INTEGRAL
  17. SGR1806-20: Swift-BAT detection of a large normal burst
  18. GRB050128: Faulkes Telescope South observations
  19. GRB 050124: Radio Observations
  20. GRB 050128: near-infrared observations with REM
  21. GRB050128,optical observations
  22. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  23. GRB050126: Updated Swift XRT Position
  24. SGR 1806-20: GMRT results at 240 MHz band.
  25. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  26. GRB 050126: Radio Observations
  27. GRB050128 Swift-BAT observations
  28. GRB 050128: Swift XRT prompt afterglow position
  29. HETE #3667: P60 Observations
  30. GRB 050124: K-band afterglow observations
  31. GRB050126: MASTER optical limit for KECK OT
  32. GRB050126: Burst Parameters Measured by BAT
  33. GRB050126: MASTER optical observations
  34. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  35. GRB 050126: Prompt XRT detection and localization
  36. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  37. GRB050124: No Swift UVOT Detection of Afterglow Emission
  38. GRB 050124, SMARTS optical/IR observations
  39. GRB 050117a: Radio Observations
  40. GRB 050124 I-band observation
  41. GRB 050124: NIR Candidates from Keck/NIRC
  42. GRB050124,optical observation
  43. GRB 050124 : Lulin R-band follow-up observation
  44. GRB050124: Updated Swift XRT Position and Fluxes
  45. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  46. GRB050124: Refined BAT position, spectral and fluence information
  47. GRB050124: Swift-BAT position of a double-peaked burst
  48. GRB 050123 : I-band follow-up observation
  49. GRB050123: optical limit 1.8h before GRB
  50. GRB050123,optical observation
  51. GRB 050123: KAIT observations
  52. GRB050123: P60 Observations
  53. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  54. CFHTLS optical transient unlikely to be a GRB
  55. Unusual optical transient (GRB ???)
  56. GRB050117a: Radio Observations
  57. GRB050117a: Refined analysis
  58. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  59. GRB050117: Palomar WIRC Ks-band observations
  60. GRB050117b: Swift-BAT detection of a weak burst
  61. GRB050117: optical observation
  62. GRB 050117, I-band observations
  63. GRB 050117: Optical observation
  64. GRB050117: Refined XRT position
  65. GRB050117: MASTER optical observations
  66. MASTER:GRB050117 SWIFT
  67. GRB050117: Swift-BAT detection of a long multi-peaked burst
  68. GRB050117: Swift XRT Position
  69. SGR 1806-20: RXTE/PCA pulse frequency during flare
  70. Triangulation of Short Hard GRB050112 (large error box)
  71. SGR 1806-20: Further VLA Observations
  72. SGR 1806-20: Further low frequency GMRT results
  73. SGR 1806-20: Further VLA Observations
  74. SGR1806-20: Swift-BAT observations of two additional bursts
  75. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  76. Further VLA observations of SGR 1806-20
  77. SGR 1806-20 and extragalactic short-duration GRBs
  78. Further ATCA observations of SGR 1806-20
  79. Fourth Epoch VLA observations of SGR 1806-20
  80. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  81. SGR 1806-20: Temporal and Spectral behavior of radio transient
  82. ATCA observations of SGR 1806-20
  83. SGR 1806-20, RHESSI observations of the 041227 giant flare
  84. Third epoch observations of SGR 1806-20 with VLA
  85. Second Epoch VLA observations of SGR 1806-20
  86. Second-epoch VLA observations of SGR 1806-20
  87. SGR1806: Detection of a Sudden Ionospheric Disturbance
  88. DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20
  89. VLA observations of SGR 1806-20
  90. SGR1806 VLA Observations
  91. VLA observations of SGR 1806-20
  92. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  93. GRB 041217: Optical observations
  94. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  95. GRB041219, early time observations
  96. Detection of the SGR 1806-20 giant outburst back-scattered by the
  97. The giant outburst from SGR 1806-20
  98. IPN localization of giant flare from SGR1806-20
  99. Giant flare from SGR 1806-20 detected by INTEGRAL
  100. GRB041228: ROTSE-III Optical Observations

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