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. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  2. GRB 260706A: ATCA detection of possible radio counterpart
  3. GRB 260705A: ATCA radio observations
  4. GRB 260714A: Fermi GBM Final Real-time Localization
  5. EP260713a: Einstein Probe detection of an X-ray transient
  6. GRB 260619A: SVOM/VT continuous optical observations
  7. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  8. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  9. EP260623a: KAIT optical observations
  10. EP260711a: EP-FXT follow-up observation
  11. GRB 260708A: GRANDMA Optical Observations
  12. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  13. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  14. GRB 260710A: Insight-HXMT/HE detection
  15. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  16. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 260708A: LCO optical observations
  19. EP260711a: Einstein Probe detection of an X-ray transient
  20. GRB 260710A: Fermi GBM Detection
  21. GRB 260709A: SVOM/GRM detection
  22. GRB 260709A: GECAM-B observation
  23. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  24. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  25. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  26. GRB 260705C: AstroSat CZTI detection
  27. GRB 260710A: Fermi GBM Final Real-time Localization
  28. GRB 260708A: Glowbug gamma-ray detection
  29. GRB 260704A: SVOM/ECLAIRs refined analysis
  30. GRB 260706A : GRANDMA Upper limits
  31. GRB 260708A: Kilonova-Catcher optical afterglow detection
  32. GRB 260708A: GECAM-B observation of a burst
  33. IceCube-260708A: One candidate from the Zwicky Transient Facility
  34. GRB 260708A: Fermi-GBM observation
  35. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  36. IceCube Alert 260709A: Global MASTER-Net observations report
  37. GRB 260709A: Fermi GBM Final Real-time Localization
  38. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  39. LAT GRB260708.42: Global MASTER-Net observations report
  40. GRB260708B: MAXI/GSC detection
  41. GRB 260708A: Fermi-LAT detection
  42. GRB 260705B: SVOM/GRM observation
  43. GRB 260708A: Fermi-GBM detection
  44. GRB 260706A: Further EP-FXT follow-up observation
  45. GRB 260706A: SVOM/VT optical upper limits
  46. EP260707a (by EP-FXT): NOT optical upper limit
  47. EP260707a is not a real source
  48. EP260707a: LCOGT Optical Upper Limit
  49. EP260707a: TRT optical upper limit
  50. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  51. EP260707a: Einstein Probe detection of an X-ray transient
  52. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  53. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  54. GRB 260705C: Glowbug gamma-ray detection of a short burst
  55. GRB 260706A: SVOM/ECLAIRs refined analysis
  56. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  57. GRB 260706A: SVOM/GRM observation
  58. GRB 260706A: REM optical/NIR observations
  59. IceCube-260704A: No candidates from the Zwicky Transient Facility
  60. GRB 260706A: LCO optical upper limit
  61. GRB 260706A: EP-FXT follow-up observation
  62. GRB 260707A: Fermi GBM Final Real-time Localization
  63. The EP-WXT trigger 01709274151 is likely a flaring star
  64. The EP-WXT trigger 01709274141 is likely a flaring star
  65. GRB 260706A: Fermi GBM Observation
  66. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  67. IPN triangulation of GRB 260627A
  68. GRB 260705A: SVOM/ECLAIRs refined analysis
  69. GRB 260706A: SVOM detection of a burst
  70. GRB 260706A: Fermi GBM Final Real-time Localization
  71. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  72. The EP-WXT trigger 01709274014 is likely a flaring star
  73. IceCube260704A: OHP/T193 optical observations
  74. GRB 260705A: LCO optical upper limits
  75. GRB 260704A: NOT optical upper limits
  76. GRB 260705C: Fermi GBM Final Localization
  77. GRB 260705B: Fermi GBM Final Real-time Localization
  78. Fermi GBM Sub-Threshold Detection of GRB 260705A
  79. GRB 260705A: SVOM detection of a burst
  80. GRB 260704A: EP-FXT follow-up observation
  81. GRB 260629A: SVOM/GRM observation of a short burst
  82. GRB 260629A: GECAM-A observation of a short burst
  83. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  84. GRB 260629A: AstroSat CZTI detection
  85. EP260703a: EP-FXT follow-up observation
  86. GRB 260704A: SVOM detection of a possible GRB
  87. GRB 260703B: Fermi GBM Final Localization
  88. EP260703a: EP-WXT detection of a fast X-ray transient
  89. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  90. Fermi trigger No 804738310: Global MASTER-Net observations report
  91. Fermi GRB 260703A: Global MASTER-Net observations report
  92. GRB 260703A: Fermi GBM Final Localization
  93. GRB 260610B: VLA detection
  94. GRB 260623A: Glowbug gamma-ray detection
  95. GRB 260614B: ATCA Radio Upper Limits
  96. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  97. Fermi trigger No 804552016: Global MASTER-Net observations report
  98. GRB 260701A: Fermi GBM Final Real-time Localization
  99. Fermi GBM trigger 804552016/260630945 is not a GRB
  100. Fermi-LAT Gamma-ray Observations of IceCube-260622A

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