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 050509A: Further I-band imaging
  2. GRB050522,optical observation
  3. GRB050520,optical observation
  4. XRF 050522: Continued NIR P200 Monitoring
  5. RBO Observations of GRB050522
  6. GRB050509b: optical observations
  7. Recent GRB BVRcIc field photometry
  8. GRB050520: Radio Observations
  9. XRF 050522: Swift XRT observation
  10. XRF050522, BVRcIc field photometry
  11. XRF 050522 : Lulin observations
  12. XRF050522: Optical Observations
  13. XRF050522: Near-infrared Observations
  14. XRF 050522: KAIT observations
  15. XRF 050522 detected with INTEGRAL
  16. GRB 050520: VLT/ULTRACAM observations
  17. Swift UVOT Observations of GRB 050520
  18. GRB 050520: Swift XRT refined analysis
  19. XRF050509C: Chandra Afterglow Detection
  20. XRF 050509c: Swift XRT Upper Limit
  21. XRF050509c: Radio Observations
  22. RBO Observations of GRB050520
  23. GRB 050520: P200 Observations
  24. GRB050520: Liverpool Telescope follow-up
  25. RBO Observations of GRB050520
  26. GRB 050520: TAROT optical limit
  27. GRB 050520: Swift XRT position
  28. GRB 050520: VLT/ULTRACAM observations
  29. GRB 050520: OSN optical observations
  30. GRB 050520: BART optical limit
  31. GRB 050520 - A long GRB detected with INTEGRAL
  32. No Swift-BAT Lightcurves in real-time for next 3 weeks
  33. Swift-BAT trigger 122203 is not a real GRB
  34. XRF 050509C: REM NIR and Optical refined analysis
  35. GRB 050504: Swift XRT afterglow candidate has faded
  36. XRF 050509c optical afterglow
  37. GRB 050509B and short GRB-SN association? (corrected)
  38. GRB 050509B and short GRB-SN association?
  39. GRB 050509B: Subaru Optical Observations
  40. GRB050502b: Early Observation
  41. GRB050509b, Bok telescope B-band imaging
  42. Refined Chandra analysis of GRB 050509b
  43. GRB050509b, SDSS pre-burst observations
  44. GRB 050509b: Keck/Chandra Cross-Correlation
  45. GRB 050509b: Keck/Chandra Cross-Correlation
  46. Chandra observation of GRB 050509b
  47. GRB 050509b: RAPTOR deep, early limits.
  48. GRB050509B: Optical/Infared observations
  49. GRB 050509b: Swift/UVOT follow-up measurements
  50. GRB 050509b Milagro GeV/TeV Observations
  51. GRB050509B: Optical observations at the Very Large Telescope
  52. GRB 050509b: No Optical Variability in XRT Error Circle
  53. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  54. GRB 050509a: Swift-BAT refined analysis
  55. GRB 050509c: ROTSE-III Optical Limits
  56. GRB 050509B: WSRT Radio Observations
  57. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  58. GRB 050505, early TAROT observation
  59. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  60. GRB 050509b: Further Analysis of Keck LRIS Images
  61. GRB050509c: REM NIR and Optical observations
  62. GRB 050509b: Physical Properties of the Candidate Host galaxy
  63. GRB 050505: SARA Observations
  64. Swift UVOT Follow-up Observations of GRB 050509B
  65. GRB 050509B, Optical Observations
  66. GRB 050509B: Swift/XRT refined analysis
  67. GRB050509a: Swift UVOT observations
  68. GRB 050509b: Optical observations
  69. GRB 050509b: Precision Astrometry
  70. GRB 050509b: Possible Optical Counterpart
  71. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  72. GRB 050509A: Optical observations
  73. GRB 050509b: Optical Counterpart Candidate
  74. GRB050509b: Radio Observations
  75. GRB 050509b: PAIRITEL and WIYN Observations
  76. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  77. GRB 050509b: optical observations
  78. GRB 050509b: Swift XRT Position
  79. GRB 050509B: ROTSE-III Optical Limits
  80. Swift Detection of GRB050509b: A short duration burst
  81. GRB 050509a: Swift XRT Position
  82. Swift Detection of the Burst GRB050509
  83. Swift-BAT detection of GRB 050507
  84. GRB 050505: Keck I-band Magnitude
  85. GRB 050505: early time observations
  86. GRB 050505 - Faulkes Telescope North observations
  87. GRB 050502a: Swift XRT Upper Limit
  88. GRB 050505, simultaneous optical observation
  89. GRB050505: Infrared observations
  90. GRB 050505: Further Swift UVOT observations.
  91. GRB050505: AAVSO observations
  92. GRB050416A : 1 GHz limit from GMRT
  93. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  94. GRB 050505 UVOT
  95. GRB050505: Optical Afterglow Candidate
  96. GRB 050505: Swift XRT Position
  97. GRB050505 Swift-BAT refined analysis
  98. GRB 050502a: Optical Observations
  99. GRB 050416b:Swift XRT afterglow upper limits
  100. GRB 050416b:Swift XRT afterglow upper limits

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