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"

36212 results found.

  1. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  2. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  3. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  4. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  5. GRB260310A / AT2026fgk: P200 Spectroscopy
  6. GRB 260312B: Glowbug gamma-ray detection
  7. GRB 260310A: Fermi GBM Observation
  8. GRB 260310A: potential optical counterpart
  9. Fermi GRB 260312B: Global MASTER-Net observations report
  10. Fermi GRB 260311B: Global MASTER-Net observations report
  11. Swift BAT trigger 1500148: A solar flare
  12. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  13. GRB 260312B: Fermi GBM Final Real-time Localization
  14. GRB 260310B: GECAM-B observation of a burst
  15. Retraction of GCN 43965: GRB is actually solar flare
  16. GRB 260312A: Swift detection of a burst
  17. GRB 260311B: Fermi GBM Final Real-time Localization
  18. GRB 260131A/B: radio detection with the VLA
  19. GRB260307A: GECAM-B observation of a burst
  20. GRB 260308A: SVOM/GRM observation of a short GRB
  21. EP260306a: Mondy optical upper limit
  22. GRB 260310A: AstroSat CZTI detection of a long burst
  23. GRB 260311A: Fermi GBM Final Real-time Localization
  24. Fermi GRB 260310B: Global MASTER-Net observations report
  25. GRB 260310B: Fermi GBM Final Real-time Localization
  26. Fermi GRB 260310A: Global MASTER-Net observations report
  27. GRB 260307B: SVOM/ECLAIRs refined analysis
  28. GRB 260208A: radio detection with the VLA
  29. GRB 260310A: Fermi GBM Final Real-time Localization
  30. GRB 260307A: Glowbug gamma-ray detection
  31. GRB 260308A: Fermi GBM Final Real-time Localization
  32. Fermi GBM Sub-Threshold Detection of GRB 260307B
  33. GRB 260307B: Mephisto optical upper limits
  34. GRB 260307B: possible NOT optical counterpart
  35. GRB 260307B: SVOM/VT upper limit with X band data analysis
  36. Fermi GRB 260307A: Global MASTER-Net observations report
  37. GRB 260307B: SVOM/VT optical candidate
  38. GRB 260307B: SVOM/C-GFT upper limit
  39. GRB 260307B: SVOM detection of a burst
  40. GRB 260307A: Fermi GBM Final Localization
  41. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  42. GRB 260207A: TESS Detection and Possible VLA Counterpart
  43. EP260302a: Optical afterglow rebrightening
  44. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  45. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  46. GRB 260303A: 1.3m DFOT optical upper limit
  47. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  48. GRB 260303A: SVOM/ECLAIRs refined analysis
  49. Fermi GRB 260305A: Global MASTER-Net observations report
  50. GRB 260305A: Fermi GBM Final Real-time Localization
  51. GRB 260303B: AstroSat CZTI detection
  52. GRB 260304A: AstroSat CZTI detection of a long burst
  53. GRB 260303A: SVOM/VT optical observations
  54. GRB 260303A: J-band observations with WINTER
  55. GRB 260303B: NuSTAR detection of prompt emission
  56. Fermi GRB 260303B: Global MASTER-Net observations report
  57. GRB 260228A: SVOM/ECLAIRs refined analysis
  58. GRB 260225A: SVOM/ECLAIRs refined analysis
  59. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  60. GRB 260303B: Fermi GBM Final Real-time Localization
  61. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  62. GRB 260303A: SVOM detection of a burst
  63. GRB 260228A: EP-FXT follow-up observation
  64. GRB 251130B: TERI Gamma-ray detection
  65. GRB 260208A: TERI Gamma-ray detection
  66. GRB 260302A: Fermi GBM Final Real-time Localization
  67. EP260227a: Mondy optical observations
  68. GRB 260228A: CAHA 2.2m telescope optical upper limit
  69. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRID detection of GRB 260225D
  71. GRB 260228A: SVOM/VT optical upper limits
  72. GRB 260225D: SVOM/GRM observation
  73. GRB 260225B: SVOM/GRM observation
  74. GRB 260228A: SVOM detection of a burst
  75. GRB 260226A: Asiago r-band upper limit
  76. GRB 260225A: SVOM/VT optical continued observations and upper limit
  77. GRID detection of GRB 260223A
  78. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  79. Konus-Wind detection of GRB 260226A
  80. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  81. EP260214a: VLT/FORS2 optical observations
  82. GRB 260225A: WINTER J-band upper limit
  83. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 260226A: COLIBRÍ optical upper limits
  85. GRB 260226A: LCOGT Optical Upper Limit
  86. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  87. GRB 260226A: Glowbug gamma-ray detection
  88. GRB 260226A: NuSTAR detection of bright prompt emission
  89. GRB 260226A : GROWTH-India Telescope optical observations
  90. GRB 260226A: LAST optical upper limit
  91. GRB 260226A: Fermi GBM observation
  92. GRB 260226A: Fermi-LAT refined analysis
  93. Fermi GRB 260226A: Global MASTER-Net observations report
  94. GRB 260226A: AstroSat CZTI detection of bright long burst
  95. EP260214a: VLA 6 GHz detection
  96. GRB 260226A: Fermi-LAT detection of a bright burst
  97. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  98. GRB260225A: SVOM/ECLAIRs refined position
  99. GRB 260226A: Fermi GBM Final Real-time Localization
  100. GRB 260225A: EP-FXT follow-up observation

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