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"

45629 results found.

  1. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  2. GRB 260809A: J-band upper limit with WINTER
  3. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  4. GRB 260806A: Glowbug gamma-ray detection
  5. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  6. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  7. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  8. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  9. The EP-WXT trigger 01709278015 is likely a flaring star
  10. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  11. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  12. GRB 260809A: NOT optical observations
  13. GRB260809A: MAO/AZT-22 optical observations
  14. GRB260809A: OHP/T193 optical observations
  15. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 260809A: SVOM/VT optical counterpart
  17. EP260809a: J-band upper limit with WINTER
  18. GRB 260808B: J-band upper limit with WINTER
  19. GRB 260808B: SVOM/ECLAIRs refined analysis
  20. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  21. GRB 260809A: SVOM detection of a faint burst
  22. GRB 260808B: Liverpool Telescope optical observations
  23. GRB 260808B: NOT optical observations
  24. GRB 260808B: LCO optical observations
  25. GRB 260808A: NuSTAR detection of prompt emission
  26. EP260809a: COLIBRÍ optical observations
  27. EP260809a: LCO optical observation
  28. EP260809a: OHP/T193 optical observations
  29. GRB260808B: OHP/T193 optical observations
  30. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  31. EP260809a: Einstein Probe detection of an X-ray transient
  32. GRB 260808B: SVOM/VT optical afterglow confirmation
  33. GRB 260808C: Fermi GBM Final Real-time Localization
  34. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  35. GRB 260808B: SVOM/VT optical candidate from VHF data
  36. GRB 260808B: SVOM detection of a faint burst
  37. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  38. Fermi GRB 260808A: Global MASTER-Net observations report
  39. GRB 260808A: Fermi GBM Final Real-time Localization
  40. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  41. IceCube Alert 260807A: Global MASTER-Net observations report
  42. IceCube-260805A: One candidate from the Zwicky Transient Facility
  43. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  44. GRB 260807A: SVOM possible detection of a faint burst
  45. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  46. EP260806a: COLIBRÍ optical observations
  47. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  48. EP260806a: SVOM/VT optical observation
  49. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  50. EP260806a: OSIRIS+/GTC redshift z=0.089
  51. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  52. EP260806a: LCO likely optical counterpart
  53. EP260806a: Einstein Probe detection of an X-ray transient
  54. GRB 260715A: cubesat Avion detection
  55. GRB 260709A: cubesat Avion detection
  56. GRB 260708A: cubesat Avion detection
  57. SN 2026stf / GRB 260708A: ATLAS forced photometry
  58. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 260730B: Glowbug gamma-ray detection
  60. GRB 260805C: Glowbug gamma-ray detection
  61. GRB 260805B: Glowbug gamma-ray detection
  62. Fermi GRB 260805A: Global MASTER-Net observations report
  63. GRB 260805B: Fermi GBM Final Localization
  64. GRB 260804A: Glowbug gamma-ray detection
  65. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  66. GRB 260805A: Fermi GBM Final Localization
  67. AT 2026wki: EP/FXT follow-up observations
  68. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  69. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  70. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  71. GRB 260804A: Fermi GBM Final Real-time Localization
  72. GRB 260708A: LCO further optical observations show supernova features
  73. GRB 260803A: Fermi GBM Final Real-time Localization
  74. Fermi GRB 260802B: Global MASTER-Net observations report
  75. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  76. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  77. GRB 260802A: SVOM/VT optical upper limits from VHF data
  78. GRB 260802A: LCO optical upper limits
  79. GRB 260802B: Fermi GBM Final Localization
  80. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  81. The EP-WXT trigger 01709277420 is likely a flaring star
  82. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  83. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  84. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  85. GRB 260731A: AstroSat CZTI detection of a long burst
  86. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  87. GRB 260730B: AstroSat CZTI detection
  88. EP260731a: COLIBRÍ optical upper limit
  89. EP260731a: NOT optical upper limit
  90. GRB 260730B: NuSTAR detection of prompt emission
  91. EP260731a: Einstein Probe detection of an X-ray transient
  92. GRB 260727A: SVOM/ECLAIRs refined analysis
  93. GRB 260726A: SVOM/ECLAIRs refined analysis
  94. GRB260730A: Fermi GBM Final Localization
  95. EP260728a: COLIBRÍ optical upper limit
  96. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  97. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  98. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  99. EP260729a: Einstein Probe detection of an X-ray transient
  100. EP260727a: SAO RAS optical observations

Advanced

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