Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28253 results found.

  1. GRB250427A/EP250427a GIT optical afterglow detection:
  2. EP250427a: LT optical counterpart detection
  3. GRB 250427A: Swift-XRT refined Analysis
  4. EP250427a / GRB 250427A: LCO optical counterpart detection
  5. EP250427a: REM optical/NIR afterglow detection
  6. GRB 250424A: LCO optical observation
  7. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  8. EP250427A: COLIBRÍ Optical Detection
  9. EP250427a: TRT optical counterpart detection
  10. EP250427a: Einstein Probe detection of a fast X-ray transient
  11. GRB 250424A: Swift-BAT refined analysis
  12. GRB 250424A: SVOM/GRM observation of a long burst
  13. GRB 250424A: PRIME near-infrared detection
  14. GRB 250424A: WINTER J-band detection
  15. GRB 250424A: EIRSAT-1 GMOD Detection
  16. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 250419A: Mondy Optical Observations
  19. GRB 250424A: Swift/UVOT Detection
  20. Fermi-LAT gamma-ray observations of IceCube-250421A
  21. GRB 250424A: Skynet Optical Observations
  22. GRB 250424A: Kilonova-Catcher optical afterglow detection
  23. GRB 250330B: GRBAlpha detection
  24. GRB 250424A: Swift-XRT refined Analysis
  25. GRB 250424A: Enhanced Swift-XRT position
  26. GRB 250424A: AstroSat CZTI detection of a bright long burst
  27. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  28. GRB 250424A: BlackGEM optical afterglow detection
  29. GRB 250424A: DDOTI Afterglow Detection
  30. GRB 250424A: REM optical/NIR afterglow detection
  31. GRB 250424A: Swift detection of a burst with an optical counterpart
  32. Swift GRB 250424A: Global MASTER-Net OT detection
  33. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  34. EP250421a: Nickel optical upper limit
  35. EP250421a: Upper limits from Fermi-GBM Observations
  36. SVOM/sb25042207: SVOM detection of an X-ray transient
  37. IceCube-250421A: DDOTI Detection of the LAST Candidate
  38. GRB 250419A: Mephisto Multi-band Optical Detection
  39. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  40. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  41. EP250421a: NOT optical observations
  42. GRB 250419A: Optical Observations via Virtual Telescope Project
  43. EP250421a: REM optical upper limit
  44. EP250421A: COLIBRÍ Optical Upper Limit
  45. GRB 250419A: Mondy Continued Optical Observations
  46. GRB 250421B: AstroSat CZTI detection of a bright long burst
  47. EP250421a: Einstein Probe detection of an X-ray transient
  48. EP250421a: Mephisto optical counterpart confirmation
  49. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  50. EP250421a: JinShan likely optical counterpart
  51. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  52. GRB 250419A: LCO optical observation
  53. GRB 250419A: JinShan optical observations
  54. GRB 250419A: SVOM/C-GFT optical observations
  55. GRB 250419A: Swift/UVOT Follow up
  56. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  57. GRB 250419A: LCO optical afterglow multi-band observations
  58. GRB 250419A: Mondy and AbAO Optical Observations
  59. GRB 250419A: AKO Optical Afterglow Detection
  60. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  61. GRB 250419A: Swift-XRT refined Analysis
  62. GRB 250419A: KAIT optical afterglow observations
  63. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  64. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  65. GRB 250419A: SVOM detection of a soft burst
  66. EP250416a: Swift/XRT counterpart fading
  67. EP20250416a: Swift/XRT counterpart detection
  68. IceCube-250416A: DDOTI Optical Observations
  69. EP250416a: Gemini South-GMOS optical counterpart
  70. SVOM/sb25041603 is not a GRB
  71. EP250416a: GSP optical upper limit
  72. EP250416a: Einstein Probe detection of an X-ray transient
  73. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  74. SVOM/sb25041603: SVOM detection of an X-ray transient
  75. IceCube 250414.324: DDOTI Optical Observations
  76. GRB 250413A: AstroSat CZTI detection
  77. EP250304a: ATCA radio observations
  78. EP250404a: Nanshan 0.43m Telescope optical observatios
  79. GRB 250411A: DDOTI Optical Observations
  80. Fermi GRB 250411A: Global MASTER-Net observations report
  81. GRB 250407A: Continued KAIT/Nickel optical observations
  82. GRB 250314A: e-MERLIN observations
  83. GRB 250407A: Mondy and AbAO Optical Observations
  84. EP250227a: Further NOT optical observations
  85. GRB 250320B: cubesat Avion detection
  86. IceCube-250406A: Swift-XRT observations
  87. GRB 250407A: LCO detection of a fading optical counterpart
  88. Fermi-LAT gamma-ray observations of IceCube-250406A
  89. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 250407A: SVOM/GRM observation of a bright long burst
  91. GRB 250407A: EP-WXT afterglow detection
  92. EP250407a: EP-WXT detection of a fast X-ray transient
  93. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  94. GRB 250407A: KAIT Optical Afterglow Candidate
  95. IceCube-250406A: No candidates from the Zwicky Transient Facility
  96. GRB 250407A: Fermi GBM Detection
  97. GRB 250407A: Swift-XRT afterglow detection
  98. GRB 250407A: SRG/ART-XC afterglow detection
  99. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  100. IceCube 250406A: DDOTI Optical Observations of the Refined Position

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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