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"

28229 results found.

  1. EP260210a: Einstein Probe detection of an X-ray transient
  2. GRB 260207B: AstroSat CZTI detection
  3. GRB 260208C: SVOM/GRM observation
  4. GRB 260204A: Swift-XRT afterglow detection
  5. GRB 260208B: AstroSat CZTI detection of a bright long burst
  6. GRB260208A: Liverpool Telescope optical follow-up observations
  7. GRB 260208A: Glowbug gamma-ray detection
  8. GRB 260208A: NuSTAR detection of prompt emission
  9. GRB 260208A: Fermi GBM Observation
  10. Fermi GRB 260209A: Global MASTER-Net observations report
  11. GRB 260208B: Swift-XRT observations
  12. GRB 260131A/B: continued Mondy optical observations
  13. GRB 260204A: Swift/UVOT Upper Limits
  14. GRB 260208B: COLIBRÍ optical observations
  15. GRB 260208A: Mondy optical observations
  16. GRB 260208A: 1.3m DFOT optical detection
  17. GRB 260208A: COLIBRÍ optical observations
  18. GRB 260208B: EP-FXT observation
  19. Fermi GRB 260208C: Global MASTER-Net observations report
  20. GRB 260208B: SVOM/VT optical candidate
  21. GRB 260208A: GECAM-B observation of a bright burst
  22. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  23. GRB 260208A: SVOM/VT optical observation
  24. Fermi GRB 260208D: Global MASTER-Net observations report
  25. GRB 260208A: Swift-XRT observations
  26. GRB 260208B: SVOM/GRM observation of a bright burst
  27. GRB 260208B: Fermi GBM Detection
  28. LAT GRB 260208B: Global MASTER-Net observations report
  29. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  30. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  31. Fermi GRB 260208A: Global MASTER-Net observations report
  32. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  33. GRB 260131A/B: Mondy and Terskol optical observations
  34. Fermi GRB 260207B: Global MASTER-Net observations report
  35. GRB 260206A: Swift-XRT observations
  36. Fermi trigger No 792135758: Global MASTER-Net observations report
  37. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  38. GRB 260204A: Swift-XRT observations
  39. GRB 260204A: SVOM/VT optical candidate
  40. GRB 260204A : MASTER Global robotic net optical observations
  41. Fermi GBM Sub-Threshold Detection of GRB 260204A
  42. GRB 260204A: LCO optical upper limits
  43. EP260110a: Late GTC/EMIR near-infrared observations
  44. GRB 260121A: 239Alferov CubeSat detection
  45. GRB 260131A: KAIT optical observations
  46. GRB 251230A: MeerLICHT afterglow detection
  47. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  48. GRB 260130A: Insight-HXMT/HE detection
  49. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  50. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  51. GRB 260127A: GECAM-B observation
  52. EP260131a: Liverpool Telescope optical upper limits
  53. EP260131a: COLIBRÍ further observations
  54. EP260131a: SVOM/VT optical observation
  55. EP260131a: Xinglong optical upper limit
  56. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  57. GRB 260131A/B: Fermi GBM Observation
  58. EP260131a: COLIBRÍ observations of slow optical fading
  59. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  60. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  61. GRB 260131B: MAXI/GSC detection
  62. EP260131a: COLIBRÍ optical observations of the counterpart
  63. EP260131a: Las Cumbres detection of an optical counterpart
  64. GRB 260127B: AstroSat CZTI detection
  65. GRB 260130A: Fermi GBM Detection
  66. EP260131a: Einstein Probe detection of an X-ray transient
  67. GRB 260127B: Fermi GBM Detection
  68. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  69. Fermi GRB 260130A: Global MASTER-Net observations report
  70. Fermi GRB 260129A: Global MASTER-Net observations report
  71. GRB 260128B: LCO optical upper limits
  72. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  73. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  74. GRB 260127A: Swift-BAT refined analysis
  75. GRB 260127B: Swift-XRT observations
  76. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  77. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  78. EP260128a: NOT optical counterpart candidate
  79. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  80. EP260128a: Liverpool Telescope optical observations and possible counterpart
  81. EP260128a: LCO optical upper limits
  82. EP260128a: Global MASTER-Net observations report
  83. EP260128a: Einstein Probe detection of an X-ray transient
  84. Fermi GRB 260127A: Global MASTER-Net observations report
  85. GRB 260127A: Fermi GBM Observation
  86. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 260127A: COLIBRÍ optical observations
  88. EP260126a: Seimei/TriCCS optical upper limit
  89. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  90. GRB 260127A: Swift-XRT refined Analysis
  91. GRB 260127A: SVOM/C-GFT optical observations
  92. GRB 260127A: Enhanced Swift-XRT position
  93. Fermi GRB 260127B: Global MASTER-Net observations report
  94. Swift GRB 260127A: Global MASTER-Net observations report
  95. GRB 260127A: LCO optical afterglow discovery
  96. GRB 260127A: Swift detection of a burst
  97. GRB 260125A: Swift-XRT observations
  98. EP260126a: Optical upper limit with Kinder observations
  99. EP260126a: Liverpool Telescope optical upper limits
  100. EP260126a: Further NOT optical upper limits

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