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"

28233 results found.

  1. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  2. GRB 260312B: AstroSat CZTI detection
  3. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  4. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  5. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  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. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  12. GRB 260131A/B: radio detection with the VLA
  13. EP260302a: MeerKAT radio counterpart
  14. GRB 260308A: SVOM/GRM observation of a short GRB
  15. EP260306a: Mondy optical upper limit
  16. Fermi GRB 260310B: Global MASTER-Net observations report
  17. Fermi GRB 260310A: Global MASTER-Net observations report
  18. GRB 260208A: radio detection with the VLA
  19. GRB 260307A: Glowbug gamma-ray detection
  20. Fermi GBM Sub-Threshold Detection of GRB 260307B
  21. GRB 260307B: Mephisto optical upper limits
  22. GRB 260307B: possible NOT optical counterpart
  23. GRB 260307B: SVOM/VT upper limit with X band data analysis
  24. Fermi GRB 260307A: Global MASTER-Net observations report
  25. GRB260307B: GROWTH-India Telescope optical upper limit
  26. GRB 260307B: SVOM/VT optical candidate
  27. GRB 260307B: SVOM/C-GFT upper limit
  28. GRB 260307B: SVOM detection of a burst
  29. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  30. GRB 260207A: TESS Detection and Possible VLA Counterpart
  31. EP260302a: SVOM/VT optical observation
  32. EP260306a: Gemini-North redshift z = 4.773
  33. EP260306a: SVOM/VT optical observation
  34. EP260302a: Gemini-South redshift z = 1.535
  35. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  36. EP260306a: Einstein Probe detection of an X-ray transient
  37. EP260302a: Optical afterglow rebrightening
  38. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  39. GRB 260303A: 1.3m DFOT optical upper limit
  40. Fermi GRB 260305A: Global MASTER-Net observations report
  41. GRB 260303B: AstroSat CZTI detection
  42. GRB 260303A: SVOM/VT optical observations
  43. GRB 260303A: J-band observations with WINTER
  44. GRB 260303B: NuSTAR detection of prompt emission
  45. EP260302a: Global MASTER-Net observations report
  46. Fermi GRB 260303B: Global MASTER-Net observations report
  47. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  48. EP260302a: analysis of the follow-up EP-FXT observation
  49. EP260302a: LCO observations
  50. EP260302a: BOOTES-7 optical counterpart detection at early times
  51. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  52. GRB 260303A: SVOM detection of a burst
  53. GRB 260228A: EP-FXT follow-up observation
  54. EP260302a: Einstein Probe detection of an X-ray transient
  55. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  56. GRB 251130B: TERI Gamma-ray detection
  57. GRB 260208A: TERI Gamma-ray detection
  58. EP260227a: Mondy optical observations
  59. GRB 260228A: CAHA 2.2m telescope optical upper limit
  60. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. EP260227a: Mephisto optical detection
  62. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  63. EP260227a: SVOM/VT optical observation
  64. GRB 260228A: SVOM/VT optical upper limits
  65. GRB 260225D: SVOM/GRM observation
  66. EP260227A: 3.6m DOT optical afterglow detection
  67. GRB 260225B: SVOM/GRM observation
  68. EP260227a: Liverpool Telescope optical observations
  69. EP260227a: LCOGT Optical Observations
  70. GRB 260226A: Asiago r-band upper limit
  71. EP260227a: Liverpool Telescope observations
  72. EP260227a: COLIBRÍ optical observations
  73. EP260227a: NOT optical observations
  74. EP260227a: Global MASTER-Net observations report
  75. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  76. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  77. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  78. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  79. EP260214a: VLT/FORS2 optical observations
  80. GRB 260225A: WINTER J-band upper limit
  81. GRB 260226A: COLIBRÍ optical upper limits
  82. GRB 260226A: LCOGT Optical Upper Limit
  83. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  84. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  85. GRB 260226A: Glowbug gamma-ray detection
  86. GRB 260226A: NuSTAR detection of bright prompt emission
  87. GRB 260226A : GROWTH-India Telescope optical observations
  88. GRB 260226A: LAST optical upper limit
  89. GRB 260226A: Fermi GBM observation
  90. LAT GRB260226.44: Global MASTER-Net observations report
  91. Fermi GRB 260226A: Global MASTER-Net observations report
  92. GRB 260226A: AstroSat CZTI detection of bright long burst
  93. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  94. EP260224a: LCO optical upper limits
  95. GRB 260225A: EP-FXT follow-up observation
  96. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  97. GRB 260223A: Fermi GBM Observation
  98. GRB 260225A: SVOM/VT optical upper limits
  99. EP260223a: Liverpool Telescope upper limits
  100. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) 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