Skip to main content
GCN at AAS 245, Legacy Circulars Address Retirement. 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. GRB 050908: P60 Confirmation of Optical Afterglow
  2. GRB 050908: Optical Observations
  3. GRB 050908: Swift detection of a burst
  4. Swift trigger 154073 is not a GRB
  5. GRB 050906: Optical observations at the Very Large Telescope
  6. GRB050904: CrAO optical observations
  7. GRB 050904 BAT refined analysis of complete data set
  8. GRB 050904: Subaru Optical Spectroscopy
  9. GRB 050906: MARGE Optical Limits
  10. GRB 050906: Swift-BAT refined analysis
  11. GRB 050906: Swift XRT upper limit
  12. GRB 050906: Radio Observations
  13. GRB 050904: Keck I-band Imaging
  14. GRB050906: P60 Observations
  15. GRB 050904: more VLT NIR observations
  16. GRB 050904: BOOTES early R-band observation
  17. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  18. GRB 050906: Bright galaxy in BAT error box
  19. GRB 050906: Swift/BAT Detection of a possible burst
  20. GRB 050904: More SOAR
  21. GRB 050904: photometric redshift
  22. GRB 050904: Swift/UVOT observations
  23. GRB 050904: Afterglow Astrometry
  24. GRB 050904: NIR object inside the XRT error box
  25. GRB 050904: early Swift XRT analysis results
  26. GRB 050904: SOAR YJ and PROMPT Ic Observations
  27. GRB 050904: BAT refined analysis of partial data set
  28. GRB 050904: TAROT optical measurements
  29. GRB050904: Optical Observations
  30. GRB 050904: Environmental Constraints
  31. GRB 050904: Possible High-Redshift GRB
  32. GRB 050904: SOAR/PROMPT Observations
  33. GRB050904: P60 Observations
  34. GRB 050904: TAROT optical limits
  35. GRB050904: Swift-BAT detection of a probable burst
  36. Swift-BAT triggers 153461-153465 are not GRBs
  37. Retraction of Swift-BAT trigger #153355
  38. GRB 050824: MDM Observations
  39. GRB 050827: Swift XRT preliminary analysis results
  40. IBAS Alerts 2641 and 2642: not a real GRB
  41. Swift Trigger #152652 is not a GRB
  42. GRB 050827 : OSN 1.5m optical observations
  43. GRB 050827: P200 NIR Observations
  44. GRB050827: Swift/UVOT upper limits
  45. GRB 050827: Optical Limit
  46. GRB 050827: XRT possible afterglow detection
  47. GRB 050826 : Lulin R band observation
  48. GRB050824: Maidanak optical limits
  49. GRB050820A: RTT150 optical observations
  50. GRB050827: RTT150 optical observations
  51. GRB 050827: Swift-BAT refined analysis
  52. GRB050827: Swift-BAT detection of a burst
  53. Subaru Observations of GRB050724
  54. GRB 050826: Optical Candidate
  55. GRB050824, HETE-2 Observation
  56. GRB 050826: Swift XRT preliminary analysis results
  57. GRB 050826: BAT refined analysis
  58. GRB050826: Swift/UVOT early upper limits
  59. GRB050824: First 2 hours of power low optical decay?
  60. GRB 050826: Swift XRT position
  61. GRB050826: Swift-BAT detection of a long burst
  62. GRB050824: MASTER final analysis of the OT observations
  63. Possible GRB050825:MASTER optical observations
  64. Swift-BAT trigger 152038 is definitely not a GRB
  65. GRB050824: CORRECTION to UVOT observing times
  66. Swift-BAT trigger 152038 is probably not a GRB
  67. GRB050824: Swift/UVOT detection of fading afterglow
  68. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  69. GRB050824, I-band imaging
  70. GRB050824: Radio Observations
  71. GRB 050824: Spectroscopic redshift from the VLT
  72. GRB 050822: refined XRT analysis
  73. GRB 050824: XRT refined analysis and possible afterglow detection
  74. GRB 050824: BAT refined analysis of a soft weak burst
  75. GRB050824: MASTER:OT decay
  76. GRB050824: MASTER observation OT
  77. GRB050805a: MASTER optical candidat
  78. GRB 050824: ROTSE-III Optical Limits
  79. GRB050824: Swift-BAT detection of a burst
  80. GRB 050824 optical candidate
  81. GRB050820A: RTT150 optical observations
  82. GRB050820a: PROMPT RcIc Observations
  83. GRB050815: Maidanak optical observation
  84. XRF050509c: Radio upper limits from GMRT
  85. VLT/UVES spectroscopy of GRB050820
  86. GRB050822: Swift/UVOT upper limits
  87. GRB 050820A BAT observations of second, larger episode of emission
  88. GRB050813: Maidanak I-band observations
  89. GRB 050822: Swift-BAT refined analysis
  90. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  91. GRB050820B at FRAM
  92. GRB050820A: RTT150 optical observations
  93. GRB 050820a - corrections to GCN 3846
  94. Swift/UVOT UV Photometry of GRB 050820B
  95. GRB 050822: ROTSE-III Prompt Optical Limits
  96. GRB 050822: Swift detection of a long burst
  97. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  98. GRB050820A: Radio Observation
  99. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  100. GRB050820a BVRcIc field photometry

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