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"

12126 results found.

  1. GRB 251025B: Swift-XRT afterglow detection
  2. GRB 251024A: Swift-XRT refined Analysis
  3. GRB 251025B: MASTER OT detection
  4. GRB 251025A: SVOM detection of a faint burst
  5. GRB 251024A: Swift detection of a burst
  6. Swift GRB 251024A: Global MASTER-Net observations report
  7. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  8. GRB 251023C: AstroSat CZTI detection
  9. EP251023b: Global MASTER-Net observations report
  10. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  11. EP251023a: GROWTH-India Telescope optical observations
  12. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  13. EP#01709247298: Swift-XRT counterpart detection
  14. GRB 251013C: further SAO RAS optical observations
  15. GRB 251013C: ISON-Castelgrande observatory optical observations
  16. GRB 251022A: MASTER OT detection
  17. EP251021b/GRB 251021A: SVOM/VT optical candidate
  18. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  19. Fermi GRB 251023A: Global MASTER-Net observations report
  20. EP251023a: Einstein Probe detection of an X-ray transient
  21. EP/WXT 01709247295: GOTO optical afterglow candidate.
  22. GRB 251022A: GOTO optical counterpart detection
  23. GRB 251022A: Fermi-LAT detection
  24. EP251021b: BOOTES-7 optical upper limit
  25. EP251021b: Einstein Probe detection of a fast X-ray transient
  26. GRB 251016A: SVOM/ECLAIRs refined analysis
  27. Fermi-LAT gamma-ray observations of IceCube-251018A
  28. GRB 251018A: Swift-XRT refined Analysis
  29. IceCube-251018A: Global MASTER-Net observations report
  30. GRB 251017A: COLIBRÍ photometric redshift
  31. GRB 251017A: Swift-XRT refined Analysis
  32. Swift GRB 251018A: Global MASTER-Net observations report
  33. GRB 251016A: AstroSat CZTI detection of a short burst
  34. GRB 251016B: AstroSat CZTI detection
  35. GRB 251017A: Swift detection of a burst with an optical counterpart
  36. sb25101602: Swift-XRT counterpart detection
  37. GRB 251016A: SVOM detection of a short burst
  38. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  39. Konus-Wind detection of GRB 251007A
  40. GRB 251014B: VLT/FORS2 Optical Observation
  41. GRB 251014D: Swift-XRT afterglow detection
  42. GRB 251014D: Swift detection of a burst
  43. GRB 251014C: Fermi GBM Final Localization
  44. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  45. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  46. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  47. GRB 251013C: ABObservatory optical observations
  48. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  49. GRB 251013C: AstroSat CZTI detection
  50. Fermi GRB 251013C: Global MASTER-Net observations report
  51. GRB 251013C: Swift-XRT counterpart detection
  52. GRB 251013C: SAO RAS optical observations
  53. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  54. GRB 251011B: Swift-XRT refined Analysis
  55. GRB 251011B : MASTER optical observations
  56. GRB 251011C: Fermi GBM Final Real-time Localization
  57. GRB 251010A: AstroSat CZTI detection
  58. GRB 251011A: AstroSat CZTI detection
  59. GRB 251011B: Swift detection of a burst
  60. SVOM/sb25101004: SVOM detection of a stellar flare
  61. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  62. IceCube Alert 251008A: Global MASTER-Net observations report
  63. GRB 251006B: Fermi GBM Observation
  64. GRB 251007A: AstroSat CZTI detection
  65. GRB 250917B: iTelescope T-26 upper limit
  66. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  67. GRB 251007A: Swift-XRT refined Analysis
  68. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  69. GRB 251006B/EP251006a: EP-WXT detection
  70. Fermi GRB 251006B: Global MASTER-Net observations report
  71. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  72. GRB 251006B: Fermi GBM Final Real-time Localization
  73. GRB 251003A: LAST optical observations
  74. GRB 251002A: LAST optical observations
  75. GRB 251005C: AstroSat CZTI detection
  76. GRB 251002A: Fermi GBM Observation
  77. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  78. GRB 251002A: AKO Early Optical Afterglow Detection
  79. GRB 251003A: Kilonova-Catcher optical afterglow detection
  80. GRB 251002A: Swift-XRT afterglow detection
  81. GRB 251002A: Kilonova-Catcher optical afterglow detection
  82. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  83. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  84. GRB 251003A: Swift detection of a burst
  85. Swift GRB251003A: Global MASTER-Net observations report
  86. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  87. GRB 251002A: BOOTES-6 early optical detection
  88. GRB 251002A: SAO RAS optical observations
  89. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  90. GRB 251002A: FRAM-ORM afterglow detection
  91. Fermi GRB 251002A: Global MASTER-Net observations report
  92. GRB 251001B: Swift-BAT refined analysis
  93. GRB 251001B: Swift/UVOT Detection
  94. GRB 251001B: Swift-XRT refined Analysis
  95. GRB 250930A: Fermi GBM Final Localization
  96. GRB 251001B: Swift detection of a burst
  97. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
  98. Fermi GRB 250929A: Global MASTER-Net observations report
  99. GRB 250929A: Fermi GBM Final Real-time Localization
  100. Fermi-LAT Gamma-ray Observations of IceCube-250926A

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov