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"

15250 results found.

  1. GRID detection of GRB 260320A
  2. GRB 260310A: LBT optical observations
  3. EP260321A: Mondy optical observations
  4. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  5. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  6. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  7. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  8. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  9. EP260321a: COLIBRÍ further optical observations and brightening
  10. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  11. EP260321a: GOTO detection of blue variable source
  12. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  13. EP260321a: further Kinder optical observations
  14. GRB 260320A: Insight-HXMT/HE detection
  15. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  16. EP260321a: SVOM/VT optical upper limit
  17. GRB 260321A: SVOM detection of a burst
  18. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  19. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  20. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  21. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  22. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  23. GRB 260318A: SVOM/GRM observation
  24. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  25. GRB 260318A: GECAM-B observation
  26. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  27. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  28. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  29. GRB 260310A / AT2026fgk: LCO optical observations
  30. GRB 260316B: GECAM-B observation
  31. GRB 260316B: SVOM/GRM observation
  32. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  33. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  34. GRB 260316B: AstroSat CZTI detection
  35. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  36. EP260316a: optical upper limit with Kinder observations
  37. GRB 260314A: Glowbug gamma-ray detection
  38. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  39. IceCube-260315A: COLIBRÍ optical observations
  40. EP260314a: optical upper limit with Kinder observations
  41. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  42. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  43. EP260314a: COLIBRÍ optical upper limit
  44. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  45. EP260314a: BOOTES-6/DPR optical upper limits at early times
  46. GRB 260314A: GECAM-B observation of a burst
  47. GRB 260310A/AT2026fgk: radio detection at 15GHz
  48. GRB 260310A / AT2026fgk: TNG NIR detection
  49. GRB 260310A / AT2026fgk: OASDG optical observations
  50. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  51. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  52. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  53. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  54. GRB 260313A: A Correction to the Fermi GBM Final Localization
  55. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  56. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  57. GRB 260310B: Insight-HXMT/HE detection
  58. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  59. GRB 260312B: AstroSat CZTI detection
  60. GRB 260308A: Insight-HXMT/HE detection
  61. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  62. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  63. GRB260310A / AT2026fgk: P200 Spectroscopy
  64. GRB 260310A: Fermi GBM Observation
  65. GRB 260310B: GECAM-B observation of a burst
  66. Retraction of GCN 43965: GRB is actually solar flare
  67. GRB 260312A: Swift detection of a burst
  68. GRB260307A: GECAM-B observation of a burst
  69. GRB 260308A: SVOM/GRM observation of a short GRB
  70. EP260306a: Mondy optical upper limit
  71. GRB 260310A: AstroSat CZTI detection of a long burst
  72. GRB 260307B: SVOM/ECLAIRs refined analysis
  73. GRB 260307B: Mephisto optical upper limits
  74. GRB 260307B: possible NOT optical counterpart
  75. GRB 260307B: SVOM/VT upper limit with X band data analysis
  76. GRB 260307B: SVOM detection of a burst
  77. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 260207A: TESS Detection and Possible VLA Counterpart
  79. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  80. EP260306a: Einstein Probe detection of an X-ray transient
  81. GRB 260303A: 1.3m DFOT optical upper limit
  82. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  83. GRB 260303A: SVOM/ECLAIRs refined analysis
  84. GRB 260303B: AstroSat CZTI detection
  85. GRB 260304A: AstroSat CZTI detection of a long burst
  86. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  87. GRB 260303A: SVOM/VT optical observations
  88. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  89. GRB 260228A: SVOM/ECLAIRs refined analysis
  90. GRB 260225A: SVOM/ECLAIRs refined analysis
  91. EP260302a: LCO observations
  92. EP260302a: BOOTES-7 optical counterpart detection at early times
  93. GRB 260303A: SVOM detection of a burst
  94. GRB 251130B: TERI Gamma-ray detection
  95. GRB 260208A: TERI Gamma-ray detection
  96. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  97. EP260227a: Mephisto optical detection
  98. GRID detection of GRB 260225D
  99. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  100. GRB 260225D: 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