Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

5512 results found.

  1. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  2. EP260314a: BOOTES-6/DPR optical upper limits at early times
  3. EP260314a: Global MASTER-Net observations report
  4. EP260314a: SVOM/VT optical candidate
  5. Fermi trigger No 795185313: Global MASTER-Net observations report
  6. IceCube Alert 260315A: Global MASTER-Net observations report
  7. EP260314a: Einstein Probe detection of an X-ray transient
  8. GRB 260314A: GECAM-B observation of a burst
  9. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  10. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  11. Fermi GRB 260314A: Global MASTER-Net observations report
  12. Fermi GRB 260313A: Global MASTER-Net observations report
  13. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  14. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  15. GRB 260310B: Insight-HXMT/HE detection
  16. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  17. GRB 260312B: AstroSat CZTI detection
  18. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  19. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  20. GRB 260308A: Insight-HXMT/HE detection
  21. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  22. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  23. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  24. GRB260310A / AT2026fgk: P200 Spectroscopy
  25. GRB 260312B: Glowbug gamma-ray detection
  26. GRB 260310A: potential optical counterpart
  27. Fermi GRB 260312B: Global MASTER-Net observations report
  28. Fermi GRB 260311B: Global MASTER-Net observations report
  29. The EP-WXT trigger 01709258843 is not a real source
  30. GRB 260310B: GECAM-B observation of a burst
  31. EP260302a: MeerKAT radio counterpart
  32. GRB260307A: GECAM-B observation of a burst
  33. GRB 260308A: SVOM/GRM observation of a short GRB
  34. EP260306a: Mondy optical upper limit
  35. GRB 260310A: AstroSat CZTI detection of a long burst
  36. GRB 260311A: Fermi GBM Final Real-time Localization
  37. Fermi GRB 260310B: Global MASTER-Net observations report
  38. Fermi GRB 260310A: Global MASTER-Net observations report
  39. GRB 260307B: SVOM/ECLAIRs refined analysis
  40. GRB 260307A: Glowbug gamma-ray detection
  41. Fermi GBM Sub-Threshold Detection of GRB 260307B
  42. GRB 260307B: Mephisto optical upper limits
  43. GRB 260307B: SVOM/VT upper limit with X band data analysis
  44. Fermi GRB 260307A: Global MASTER-Net observations report
  45. GRB260307B: GROWTH-India Telescope optical upper limit
  46. GRB 260307B: SVOM/VT optical candidate
  47. GRB 260307B: SVOM/C-GFT upper limit
  48. GRB 260307B: SVOM detection of a burst
  49. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  50. EP260302a: SVOM/VT optical observation
  51. EP260306a: SVOM/VT optical observation
  52. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  53. EP260306a: Einstein Probe detection of an X-ray transient
  54. EP260302a: Optical afterglow rebrightening
  55. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  56. GRB 260303A: 1.3m DFOT optical upper limit
  57. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  58. GRB 260303A: SVOM/ECLAIRs refined analysis
  59. Fermi GRB 260305A: Global MASTER-Net observations report
  60. GRB 260303B: AstroSat CZTI detection
  61. GRB 260304A: AstroSat CZTI detection of a long burst
  62. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  63. GRB 260303A: SVOM/VT optical observations
  64. GRB 260303A: J-band observations with WINTER
  65. GRB 260303B: NuSTAR detection of prompt emission
  66. EP260302a: Global MASTER-Net observations report
  67. Fermi GRB 260303B: Global MASTER-Net observations report
  68. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  69. EP260302a: analysis of the follow-up EP-FXT observation
  70. EP260227a: Gemini-South optical observations
  71. EP260302a: LCO observations
  72. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  73. GRB 260303A: SVOM detection of a burst
  74. EP260302a: Einstein Probe detection of an X-ray transient
  75. GRB 260228A: CAHA 2.2m telescope optical upper limit
  76. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. EP260227a: further LCO observations
  78. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  79. EP260227a: Liverpool Telescope observations
  80. EP260227a: Global MASTER-Net observations report
  81. GRB 260226A: COLIBRÍ optical upper limits
  82. LAT GRB260226.44: Global MASTER-Net observations report
  83. Fermi GRB 260226A: Global MASTER-Net observations report
  84. EP260224a: LCO optical upper limits
  85. EP260224a: Einstein Probe detection of an X-ray transient
  86. Fermi GRB 260223A: Global MASTER-Net observations report
  87. Fermi GRB 260221B: Global MASTER-Net observations report
  88. Fermi GRB 260221A: Global MASTER-Net observations report
  89. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  90. IceCube Alert 260217A: Global MASTER-Net observations report
  91. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  92. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  93. EP260214b: GROWTH-India Telescope optical upper limit
  94. EP260214a: NOT optical upper limits
  95. EP260214b: Einstein Probe detection of a fast X-ray transient
  96. EP260213a: SVOM/VT optical upper limit
  97. EP260213a: refined analysis of the EP-FXT observation
  98. Fermi GRB 260212A: Global MASTER-Net observations report
  99. Fermi GRB 260210C: Global MASTER-Net observations report
  100. Fermi GRB 260209A: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov