Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

40764 results found.

  1. GRB 260320A: Glowbug gamma-ray detection
  2. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  3. EP260321a: COLIBRÍ further optical observations and brightening
  4. Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
  5. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  6. EP260214b: ATCA 6 GHz detection
  7. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  8. GRB 260321A: EP-FXT follow-up observation
  9. The EP-WXT trigger 01709259045 is likely a flaring star
  10. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  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 260321A: SVOM/VT optical upper limits
  15. EP260321a: Las Cumbres upper limit
  16. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 260320A: Insight-HXMT/HE detection
  18. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  19. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  20. EP260321a: SVOM/VT optical upper limit
  21. GRB 260310A: continued optical observation at Mondy
  22. Fermi GBM Sub-Threshold Detection of GRB 260321A
  23. GRB 260321A: SVOM detection of a burst
  24. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  25. EP260321a: Global MASTER-Net observations report
  26. EP260321a: Einstein Probe detection of an X-ray transient
  27. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  28. GRB 260318A: Glowbug gamma-ray detection
  29. GRB 260310A / AT 2026fgk: KAIT optical observations
  30. GRB 260320A: NuSTAR detection of prompt emission
  31. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  32. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  33. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  34. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  35. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  36. GRB 260310A/AT2026fgk: LBT near-infrared observations
  37. NOEMA Detection of GRB 260310A / AT 2026fgk
  38. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  39. GRB 260318A: SVOM/GRM observation
  40. The EP-WXT trigger 01709258989 is likely a flaring star
  41. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  42. GRB 260318A: GECAM-B observation
  43. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  44. Fermi GRB 260318A: Global MASTER-Net observations report
  45. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  46. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  47. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  48. GRB 260310A / AT 2026fgk: radio detection with the VLA
  49. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  50. GRB 260310A / AT2026fgk: LCO optical observations
  51. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  52. GRB 260316B: GECAM-B observation
  53. GRB 260316B: SVOM/GRM observation
  54. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  55. EP260316a: COLIBRÍ faint optical counterpart candidate
  56. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  57. GRB 260316B: AstroSat CZTI detection
  58. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  59. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  60. EP260316a: Xinglong optical upper limit
  61. EP260316a: optical upper limit with Kinder observations
  62. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  63. GRB 260314A: Glowbug gamma-ray detection
  64. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  65. IceCube-260315A: COLIBRÍ optical observations
  66. EP260314a: Xinglong optical upper limit
  67. EP260314a: optical upper limit with Kinder observations
  68. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  69. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  70. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  71. GRB 260310A / AT 2026fgk: iTelescope optical observations
  72. EP260314a: COLIBRÍ optical upper limit
  73. GRID detection of GRB 260312B
  74. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  75. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  76. EP260314a: BOOTES-6/DPR optical upper limits at early times
  77. EP260314a: Global MASTER-Net observations report
  78. EP260314a: SVOM/VT optical candidate
  79. Fermi trigger No 795185313: Global MASTER-Net observations report
  80. IceCube Alert 260315A: Global MASTER-Net observations report
  81. EP260314a: Einstein Probe detection of an X-ray transient
  82. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  83. GRB 260314A: GECAM-B observation of a burst
  84. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  85. GRB 260310A / AT2026fgk: SAO RAS optical observations
  86. GRB 260310A/AT2026fgk: radio detection at 15GHz
  87. GRB 260310A / AT2026fgk: TNG NIR detection
  88. GRB 260310A / AT2026fgk: OASDG optical observations
  89. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  90. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  91. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  92. Fermi GRB 260314A: Global MASTER-Net observations report
  93. Fermi GRB 260313A: Global MASTER-Net observations report
  94. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  95. GRB 260313A: A Correction to the Fermi GBM Final Localization
  96. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  97. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  98. GRB 260310B: Insight-HXMT/HE detection
  99. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  100. GRB 260310A: NOT optical polarimetry

Advanced

Download all Circulars as a .tar.gz archive:
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