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"

45893 results found.

  1. EP260110a: Late GTC/EMIR near-infrared observations
  2. GRB 260204B: Fermi GBM Final Real-time Localization
  3. GRB 260204A: SVOM detection of a burst
  4. GRB 260121A: 239Alferov CubeSat detection
  5. Konus-Wind detection of GRB 260121A
  6. GRB 260131A/B: OHP/T193 optical observations
  7. GRB 260131A: KAIT optical observations
  8. GRB 251230A: MeerLICHT afterglow detection
  9. GRB 260131A: FTW optical and NIR observations
  10. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  11. GRID detection of GRB 260131A/B
  12. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  13. GRB 260130A: Insight-HXMT/HE detection
  14. GRB 260130A: GECAM-B observation of a short burst
  15. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  16. GRB 260131A/B: EP/FXT X-ray afterglow detection
  17. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  18. GRB 260127B: Insight-HXMT/HE detection
  19. GRB 260127B: GECAM-B observation of a short burst
  20. GRB 260127A: GECAM-B observation
  21. GRB 260131A: NOT spectroscopic redshift z = 1.434
  22. EP260131a: Liverpool Telescope optical upper limits
  23. EP260131a: COLIBRÍ further observations
  24. Konus-Wind detection of GRB 260128A / EP260128a
  25. GRB 260131A: Insight-HXMT/HE detection
  26. Konus-Wind detection of GRB 260131A/B
  27. EP260131a: SVOM/VT optical observation
  28. EP260131a: Xinglong optical upper limit
  29. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  30. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  31. GRB 260131A/B: Fermi GBM Observation
  32. EP260131a: COLIBRÍ observations of slow optical fading
  33. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  35. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  36. GRB 260131B: MAXI/GSC detection
  37. GRB 260131A: Fermi GBM Final Real-time Localization
  38. EP260131a: COLIBRÍ optical observations of the counterpart
  39. EP260131a: Las Cumbres detection of an optical counterpart
  40. GRB 260127B: AstroSat CZTI detection
  41. GRB 260130A: Fermi GBM Detection
  42. EP260131a: Einstein Probe detection of an X-ray transient
  43. GRB 260127B: Fermi GBM Detection
  44. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  45. Fermi GRB 260130A: Global MASTER-Net observations report
  46. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  47. GRB 260130A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 260129A: Global MASTER-Net observations report
  49. GRB 260128B: LCO optical upper limits
  50. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  51. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  52. IPN triangulation of GRB 260121A
  53. GRB 260127A: Swift-BAT refined analysis
  54. GRB 260129B: Fermi GBM Final Localization
  55. GRB 260128B: SVOM detection of a burst through offline search
  56. GRB 260129A: Fermi GBM Final Localization
  57. IPN triangulation of GRB 260127B (short)
  58. GRB 260127B: Swift-XRT observations
  59. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  60. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  61. EP260128a: NOT optical counterpart candidate
  62. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  63. EP260128a: Liverpool Telescope optical observations and possible counterpart
  64. EP260128a: LCO optical upper limits
  65. EP260126a: SVOM/VT optical upperlimit
  66. EP260128a: Global MASTER-Net observations report
  67. EP260128a: Einstein Probe detection of an X-ray transient
  68. Fermi GRB 260127A: Global MASTER-Net observations report
  69. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  70. GRB 260127A: Fermi GBM Observation
  71. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 260127A: COLIBRÍ optical observations
  73. GRB 260127A: NOT optical observations
  74. GRB 260127B: Swift ToO observations
  75. EP260126a: Seimei/TriCCS optical upper limit
  76. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  77. GRB 260127A: Swift-XRT refined Analysis
  78. GRB 260127B: GOTO candidate optical counterpart
  79. GRB 260127A: SVOM/C-GFT optical observations
  80. The EP-WXT trigger 01709253145 is likely a flaring star
  81. GRB 260127A: Enhanced Swift-XRT position
  82. Fermi GRB 260127B: Global MASTER-Net observations report
  83. GRB 260127B: Fermi GBM Final Real-time Localization
  84. GRB 260127A: Prompt enhanced Swift-XRT position
  85. Swift GRB 260127A: Global MASTER-Net observations report
  86. GRB 260127A: LCO optical afterglow discovery
  87. GRB 260127A: Swift detection of a burst
  88. GRB 260127A: Fermi GBM Final Real-time Localization
  89. GRB 260125A: Swift-XRT observations
  90. EP260126a: EP-FXT follow-up observation
  91. EP260126a: Optical upper limit with Kinder observations
  92. EP260126a: Liverpool Telescope optical upper limits
  93. EP260126a: Further NOT optical upper limits
  94. EP260126a: COLIBRÍ optical upper limits
  95. EP260126a: NOT optical observations
  96. EP260126a: Einstein Probe detection of a fast X-ray transient
  97. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  98. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  99. Konus-Wind detection of GRB 260120B
  100. GRB 251222A: SVOM/ECLAIRs refined analysis

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