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"

27392 results found.

  1. GRB 260303B: AstroSat CZTI detection
  2. GRB 260303A: SVOM/VT optical observations
  3. GRB 260303A: J-band observations with WINTER
  4. GRB 260303B: NuSTAR detection of prompt emission
  5. EP260302a: Global MASTER-Net observations report
  6. Fermi GRB 260303B: Global MASTER-Net observations report
  7. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  8. EP260302a: analysis of the follow-up EP-FXT observation
  9. EP260302a: LCO observations
  10. EP260302a: BOOTES-7 optical counterpart detection at early times
  11. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  12. GRB 260303A: SVOM detection of a burst
  13. GRB 260228A: EP-FXT follow-up observation
  14. EP260302a: Einstein Probe detection of an X-ray transient
  15. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  16. GRB 251130B: TERI Gamma-ray detection
  17. GRB 260208A: TERI Gamma-ray detection
  18. EP260227a: Mondy optical observations
  19. GRB 260228A: CAHA 2.2m telescope optical upper limit
  20. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. EP260227a: Mephisto optical detection
  22. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  23. EP260227a: SVOM/VT optical observation
  24. GRB 260228A: SVOM/VT optical upper limits
  25. GRB 260225D: SVOM/GRM observation
  26. EP260227A: 3.6m DOT optical afterglow detection
  27. GRB 260225B: SVOM/GRM observation
  28. EP260227a: Liverpool Telescope optical observations
  29. EP260227a: LCOGT Optical Observations
  30. GRB 260226A: Asiago r-band upper limit
  31. EP260227a: Liverpool Telescope observations
  32. EP260227a: COLIBRÍ optical observations
  33. EP260227a: NOT optical observations
  34. EP260227a: Global MASTER-Net observations report
  35. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  36. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  37. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  38. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  39. EP260214a: VLT/FORS2 optical observations
  40. GRB 260225A: WINTER J-band upper limit
  41. GRB 260226A: COLIBRÍ optical upper limits
  42. GRB 260226A: LCOGT Optical Upper Limit
  43. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  44. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  45. GRB 260226A: Glowbug gamma-ray detection
  46. GRB 260226A: NuSTAR detection of bright prompt emission
  47. GRB 260226A : GROWTH-India Telescope optical observations
  48. GRB 260226A: LAST optical upper limit
  49. GRB 260226A: Fermi GBM observation
  50. LAT GRB260226.44: Global MASTER-Net observations report
  51. Fermi GRB 260226A: Global MASTER-Net observations report
  52. GRB 260226A: AstroSat CZTI detection of bright long burst
  53. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  54. EP260224a: LCO optical upper limits
  55. GRB 260225A: EP-FXT follow-up observation
  56. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  57. GRB 260223A: Fermi GBM Observation
  58. GRB 260225A: SVOM/VT optical upper limits
  59. EP260223a: Liverpool Telescope upper limits
  60. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  61. EP260224a: Einstein Probe detection of an X-ray transient
  62. EP 260225.148: COLIBRÍ Confirmation of flaring star
  63. EP260223a: Xinglong optical upper limit
  64. GRB 260223A: Glowbug gamma-ray detection
  65. EP260213a: Mephisto optical upper limits
  66. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  67. sb26021801: SVOM/C-GFT upper limit
  68. EP260223a: COLIBRÍ optical upper limits
  69. EP260223a: Einstein Probe detection of an X-ray transient
  70. GRB 260223A: SVOM/GRM observation
  71. GRB 260223A: COLIBRÍ further optical observations and a brightening
  72. EP260221a: Optical upper limit with Kinder observations
  73. GRB 260223A: COLIBRÍ optical observations
  74. GRB 260223A: DDOTI Optical Candidate
  75. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  76. Fermi GRB 260223A: Global MASTER-Net observations report
  77. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  78. EP260221a: COLIBRÍ optical counterpart candidate
  79. EP260221a: Gemini South z-band upper limit
  80. EP260221a: Global MASTER-Net observations report
  81. EP260221a: EP-FXT follow-up observation
  82. Fermi GRB 260221B: Global MASTER-Net observations report
  83. EP-WXT01709258519: Xinglong optical upper limit
  84. EP260221a: Xinglong optical upper limit
  85. Fermi GRB 260221A: Global MASTER-Net observations report
  86. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  87. EP260221a: GOTO optical upper limit
  88. EP260221a: COLIBRÍ optical upper limit
  89. SVOM alert sb26021801: LCO optical upper limit
  90. EP260221a: Einstein Probe detection of an X-ray transient
  91. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  92. Fermi GRB 260219A: Global MASTER-Net observations report
  93. SVOM alert sb26021801: LAST optical upper limit
  94. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. IceCube Alert 260217A: Global MASTER-Net observations report
  96. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  97. sb26021801: SVOM detection of a long faint X-ray transient
  98. EP-WXT 01709258455: NOT optical upper limits
  99. EP260214b: Mondy optical observations
  100. EP260214b: 1.3m DFOT optical upper limit

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