Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"
  1. GRB 251025B: SVOM detection of a burst
  2. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  3. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  4. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. GRB 251025A: SVOM/VT VHF optical upper limit
  6. GRB 251025A: SVOM detection of a faint burst
  7. GRB 251003A: VLA Detection
  8. GRB 251024A: Enhanced Swift-XRT position
  9. GRB 251023C: Glowbug gamma-ray detection
  10. GRB 251024A: LCOGT Optical Afterglow Detection
  11. GRB 251022A: KAIT optical observations
  12. GRB 251024A: Swift detection of a burst
  13. Swift GRB 251024A: Global MASTER-Net observations report
  14. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  15. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  16. EP251023a: MAO/AZT-22 optical observations
  17. GRB 251023B: OHP/T193 optical observations
  18. EP251023a: OHP/T193 optical observations
  19. GRB 251023C: AstroSat CZTI detection
  20. EP251023b/GRB 251023B: JinShan optical observation
  21. GRB 251022A: Swift-XRT detection of GOTO25iym
  22. EP251023b: Global MASTER-Net observations report
  23. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  24. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  25. GRB 251022A: GROWTH-India Telescope optical observations
  26. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  27. EP251023a: GROWTH-India Telescope optical observations
  28. GRB 251022A: Fermi GBM Observation
  29. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  30. GRB 251023A: Glowbug gamma-ray detection
  31. GRB 251023B: Glowbug gamma-ray detection
  32. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  33. EP251023a: Global MASTER-Net observations report
  34. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  35. IPN triangulation of GRB 251016B
  36. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  37. EP#01709247298: Swift-XRT counterpart detection
  38. EP251023a: COLIBRÍ optical observations
  39. GRB 251013C: further SAO RAS optical observations
  40. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  41. GRB 251022A: COLIBRÍ optical observations
  42. GRB 251013C: ISON-Castelgrande observatory optical observations
  43. GRB 251022A: MASTER OT detection
  44. GRB 251022A: DDOTI Optical Detection
  45. EP251021b/GRB 251021A: SVOM/VT optical candidate
  46. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  47. EP251023a: NOT optical counterpart detection
  48. Fermi GRB 251023A: Global MASTER-Net observations report
  49. EP251023a: GSP Optical Counterpart Detection
  50. EP251023a: Einstein Probe detection of an X-ray transient
  51. EP/WXT 01709247295: GOTO optical afterglow candidate.
  52. GRB 251022A: GOTO optical counterpart detection
  53. GRB 251023A: Fermi GBM Final Localization Correction
  54. GRB 251022A: Fermi-LAT detection
  55. GRB 251016B: Fermi GBM Detection
  56. GRB 251022A: Tiled Swift observations
  57. LAT GRB251022A: Global MASTER-Net observations report
  58. GRB 251022A: Fermi GBM Final Real-time Localization
  59. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  60. EP251021b: BOOTES-7 optical upper limit
  61. EP251021b: Einstein Probe detection of a fast X-ray transient
  62. GRB 250911A: MAXI/GSC detection
  63. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  64. GRB 251016A: SVOM/ECLAIRs refined analysis
  65. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  67. Fermi-LAT gamma-ray observations of IceCube-251018A
  68. GRB 251017A : RAPAS follow-up observations
  69. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 251017A: COLIBRÍ optical observations of a late plateau
  71. IceCube-251018A: DDOTI Optical Upper Limit
  72. GRB 251017A: Swift-BAT refined analysis
  73. GRB 251016A: Fermi GBM Observation
  74. GRB 251018A: Fermi GBM Observation
  75. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  76. GRB 251018A: Swift-XRT refined Analysis
  77. GRB 251018A: Enhanced Swift-XRT position
  78. Fermi trigger No 782500909: Global MASTER-Net observations report
  79. GRB 251016A: HXMT/HE detection
  80. IceCube-251018A: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  82. GRB 251016A: Swift-XRT afterglow detection
  83. GRB 251017A: Swift/UVOT Detection
  84. GRB 251016A: Swift/UVOT Detection
  85. GRB 251018A: Swift/UVOT Detection
  86. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  87. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  88. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  89. GRB 251016A: VLT/FORS2 Optical Observation
  90. GRB 251017A: COLIBRÍ photometric redshift
  91. GRB 251017A: Swift-XRT refined Analysis
  92. GRB 251018A: MASTER OT detection
  93. GRB 251018A: TRT optical afterglow detection
  94. Swift GRB 251018A: Global MASTER-Net observations report
  95. GRB 251018A: Swift detection of a burst with an optical counterpart
  96. GRB 251018A: Fermi GBM Final Real-time Localization
  97. GRB 251017A: SVOM/VT optical observation
  98. GRB 251011A: Fermi GBM Observation
  99. GRB 251017A: OHP/T193 i-band observations
  100. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening

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