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"

38172 results found.

  1. GRB 251202A: Fermi GBM Observation
  2. GRB 251202A: Swift/UVOT Detection
  3. GRB 251201B: Kilonova-Catcher optical afterglow detection
  4. GRB 251201B: Swift/UVOT Detection
  5. GRB 251130B: Glowbug gamma-ray detection
  6. GRB 251201B: GECAM-B observation of a long burst
  7. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  8. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  9. GRB 251202A: GOTO optical afterglow detection
  10. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  11. GRB 251201A: GECAM-B observation of a burst
  12. GRB 251126A: SAO RAS optical marginal detection
  13. GRB 251202A: Swift-XRT afterglow detection
  14. EP251129a/GRB 251129A: NOWT Detection
  15. GRB 251126A: SVOM/VT optical observation
  16. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  17. Fermi GRB 251202A: Global MASTER-Net observations report
  18. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  19. GRB 251201B: Swift-XRT refined Analysis
  20. GRB 251202A: Fermi GBM Final Real-time Localization
  21. GRB 251201A: SVOM/GRM observation of a burst
  22. GRB 251201B: SVOM/VT optical fading
  23. Swift GRB 251201B : MASTER optical counterpart detection
  24. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  25. Swift GRB 251201B: Global MASTER-Net observations report
  26. GRB 251201B: Enhanced Swift-XRT position
  27. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  28. GRB 251130B: AstroSat CZTI detection
  29. GRB 251201B: Swift detection of a burst with an optical counterpart
  30. GRB 251201B: Fermi GBM Final Real-time Localization
  31. EP251130a: Mondy optical observations
  32. SVOM GRB251201.19: Global MASTER-Net observations report
  33. EP251130a: SAO RAS optical observations
  34. EP251130a: KAIT optical observations
  35. GRB 251201A: MAXI/GSC detection
  36. Fermi GRB 251130B: Global MASTER-Net observations report
  37. GRB 251127A: SVOM/GRM observation
  38. IceCube Alert 251130.75: Global MASTER-Net observations report
  39. GRB 251130B: Fermi GBM Final Localization Correction
  40. EP251130a: Global MASTER-Net observations report
  41. GRB 251130B: Fermi GBM Final Real-time Localization
  42. EP251129a/GRB 251129A: EP-FXT follow-up observations
  43. GRB 251130A: Fermi GBM Final Real-time Localization
  44. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  45. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  46. GRB 251128A: AstroSat CZTI detection
  47. GRB 251129A / EP251129a: SAO RAS optical observations
  48. GRB 251126A: SAO RAS optical observations
  49. GRB 251128A: GECAM-B detection
  50. GRB 251128A: SVOM/GRM observation of a long burst
  51. GRB 251128A: Insight-HXMT/HE detection
  52. SVOM GRB 251129A : MASTER optical counterpart detection
  53. GRB 251129A: Swift-XRT afterglow detection
  54. GRB 251129A: Swift ToO observations
  55. GRB 251129A / EP251129a: SVOM/VT optical fading
  56. EP251129a: Global MASTER-Net observations report
  57. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  58. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  59. GRB 251129A: Correction to the position of the optical counterpar
  60. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  61. GRB 251128A: Fermi GBM Observation
  62. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  63. GRB 251129A: SVOM detection of a burst
  64. SVOM GRB251129A: Global MASTER-Net observations report
  65. GRB 251129A: SVOM detection of a burst
  66. GRB 251126A: Swift-BAT refined analysis
  67. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  68. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  69. Fermi GRB 251128A: Global MASTER-Net observations report
  70. GRB 251127A: Glowbug gamma-ray detection
  71. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  72. GRB 251126A: further SAO RAS optical observations
  73. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  74. GRB 251126A NUTTelA-TAO Early Measurements
  75. GRB251126A: MAO/AZT-22 optical observations
  76. GRB 251128A: Fermi GBM Final Real-time Localization
  77. GRB251126A: Continued optical observation from 1.3m DFOT
  78. GRB 251126A: Swift/UVOT Detection
  79. GRB 251126A: Mondy and SAO RAS optical observations
  80. GRB 251126A: Swift-XRT refined Analysis
  81. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  82. GRB 251126A: NOT optical observations
  83. GRB 251126A: 1.3m DFOT optical afterglow detection
  84. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  85. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  86. GRB 251125B: GECAM-B detection
  87. Fermi GRB 251127A: Global MASTER-Net observations report
  88. GRB 251127A: Fermi GBM Final Real-time Localization
  89. GRB 251126A: Enhanced Swift-XRT position
  90. GRB 251126A: Kilonova-Catcher optical afterglow detection
  91. GRB 251126A: Asiago i-band detection
  92. GRB 251126A: Nanshan/HMT optical afterglow detection
  93. Swift GRB 251126A: Global MASTER-Net observations report
  94. GRB 251121A: Fermi GBM Observation
  95. GRB 251126A: Prompt enhanced Swift-XRT position
  96. GRB 251126A: GIT discovery of the likely optical afterglow
  97. GRB 251126A: Swift detection of a burst
  98. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  99. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  100. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery

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