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"
  1. GRB 260804A: Fermi GBM Final Real-time Localization
  2. GRB 260708A: LCO further optical observations show supernova features
  3. GRB 260803A: Fermi GBM Final Real-time Localization
  4. Fermi GRB 260802B: Global MASTER-Net observations report
  5. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  6. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  7. GRB 260802A: SVOM/VT optical upper limits from VHF data
  8. GRB 260802A: LCO optical upper limits
  9. GRB 260802B: Fermi GBM Final Localization
  10. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. The EP-WXT trigger 01709277420 is likely a flaring star
  12. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  13. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  14. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  15. GRB 260731A: AstroSat CZTI detection of a long burst
  16. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  17. GRB 260730B: AstroSat CZTI detection
  18. EP260731a: COLIBRÍ optical upper limit
  19. EP260731a: NOT optical upper limit
  20. GRB 260730B: NuSTAR detection of prompt emission
  21. EP260731a: Einstein Probe detection of an X-ray transient
  22. GRB 260727A: SVOM/ECLAIRs refined analysis
  23. GRB 260726A: SVOM/ECLAIRs refined analysis
  24. GRB260730A: Fermi GBM Final Localization
  25. EP260728a: COLIBRÍ optical upper limit
  26. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  27. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  28. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  29. EP260729a: Einstein Probe detection of an X-ray transient
  30. EP260727a: SAO RAS optical observations
  31. GRB 260727A: AbAO and SAO RAS optical observations
  32. EP260728a: EP-FXT follow-up observation
  33. GRB 260726A: EP-FXT follow-up observations
  34. EP260728a: Einstein Probe detection of a fast X-ray transient
  35. GRB 260727A: SVOM/GRM observation
  36. GRB 260726A: Fermi GBM Observation
  37. EP260727a: 1.5m OSN optical counterpart detection
  38. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  39. EP260727a: OHP/T193 optical observations
  40. Konus-Wind detection of GRB 260727A
  41. GRB 260726A: Liverpool Telescope optical observations
  42. GRB 260727A: Liverpool Telescope optical upper limits
  43. EP260727a: Liverpool Telescope confirmation of optical counterpart
  44. EP260727a: NUTTELA-TAO Early Optical Limits
  45. GRB 260728A: Fermi GBM Final Localization
  46. GRB 260727A: EP/FXT follow-up observations
  47. EP260727a: Einstein Probe detection of an X-ray transient
  48. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  49. GRB 260727A: Glowbug gamma-ray detection
  50. GRB 260726A: J-band upper limit with WINTER
  51. GRB 260727A: J-band upper limit with WINTER
  52. GRB 260726A: SVOM/VT optical candidate
  53. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  54. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  55. EP260723a: SVOM/ECLAIRs Upper Limit
  56. GRB 260727A: GOTO early optical upper limit
  57. GRB 260727A: AstroSat CZTI detection
  58. GRB 260727A: Kilonova-Catcher optical upper limit
  59. GRB 260727A: LCO optical upper limits
  60. GRB 260727B: Fermi GBM Final Real-time Localization
  61. Fermi GRB 260726A: Global MASTER-Net observations report
  62. GRB 260727A: SVOM detection of a bright long burst
  63. GRB 260726A: SVOM detection of a burst
  64. GRB 260726A: Fermi GBM Final Real-time Localization
  65. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  66. EP260723a: further EP-FXT follow-up observation
  67. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  68. EP260725a: EP-WXT detection of an X-ray transient
  69. GRB 260616A: cubesat Avion detection
  70. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  71. GRB 260602B: cubesat Avion detection
  72. GRB 260601A: cubesat Avion detection
  73. EP260723a: EP-FXT follow-up observation
  74. IPN triangulation of GRB 260706B
  75. GRB 260718A: SVOM/ECLAIRs refined analysis
  76. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  77. EP260723a: SVOM/VT optical observation
  78. EP260723a: COLIBRÍ optical observations
  79. EP260723a: NOT optical conterpart confirmation
  80. EP260723a: Liverpool Telescope likely optical counterpart
  81. EP260723a: EP-WXT detection of a fast X-ray transient
  82. GRB 260723A: Fermi GBM Final Localization
  83. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  85. IceCube Alert 260722A: Global MASTER-Net observations report
  86. Konus-Wind detection of GRB 260721A
  87. GRB 260722A: Fermi GBM Final Real-time Localization
  88. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  89. Fermi GBM trigger 806384210/260722151 is not a GRB
  90. GRB 260721A: NuSTAR detection of prompt emission
  91. Konus-Wind detection of GRB 260714B
  92. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  93. GRB 260705A: Retraction of optical counterpart
  94. GRB 260714B: Insight-HXMT/HE detection
  95. GRB 260718A: EP-FXT follow-up observation
  96. Fermi trigger No 806104130: Global MASTER-Net observations report
  97. Fermi GRB 260718A: Global MASTER-Net observations report
  98. GRB 260718A: LCO optical upper limits
  99. GRB 260711A: SVOM/GRM observation
  100. GRB 260710A: SVOM/GRM 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