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. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  2. EP251023a: Global MASTER-Net observations report
  3. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  4. IPN triangulation of GRB 251016B
  5. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  6. EP#01709247298: Swift-XRT counterpart detection
  7. EP251023a: COLIBRÍ optical observations
  8. GRB 251013C: further SAO RAS optical observations
  9. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  10. GRB 251022A: COLIBRÍ optical observations
  11. GRB 251013C: ISON-Castelgrande observatory optical observations
  12. GRB 251022A: MASTER OT detection
  13. GRB 251022A: DDOTI Optical Detection
  14. EP251021b/GRB 251021A: SVOM/VT optical candidate
  15. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  16. EP251023a: NOT optical counterpart detection
  17. Fermi GRB 251023A: Global MASTER-Net observations report
  18. EP251023a: GSP Optical Counterpart Detection
  19. EP251023a: Einstein Probe detection of an X-ray transient
  20. EP/WXT 01709247295: GOTO optical afterglow candidate.
  21. GRB 251022A: GOTO optical counterpart detection
  22. GRB 251023A: Fermi GBM Final Localization Correction
  23. GRB 251022A: Fermi-LAT detection
  24. GRB 251016B: Fermi GBM Detection
  25. GRB 251022A: Tiled Swift observations
  26. LAT GRB251022A: Global MASTER-Net observations report
  27. GRB 251022A: Fermi GBM Final Real-time Localization
  28. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  29. EP251021b: BOOTES-7 optical upper limit
  30. EP251021b: Einstein Probe detection of a fast X-ray transient
  31. GRB 250911A: MAXI/GSC detection
  32. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  33. GRB 251016A: SVOM/ECLAIRs refined analysis
  34. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  36. Fermi-LAT gamma-ray observations of IceCube-251018A
  37. GRB 251017A : RAPAS follow-up observations
  38. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 251017A: COLIBRÍ optical observations of a late plateau
  40. IceCube-251018A: DDOTI Optical Upper Limit
  41. GRB 251017A: Swift-BAT refined analysis
  42. GRB 251016A: Fermi GBM Observation
  43. GRB 251018A: Fermi GBM Observation
  44. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  45. GRB 251018A: Swift-XRT refined Analysis
  46. GRB 251018A: Enhanced Swift-XRT position
  47. Fermi trigger No 782500909: Global MASTER-Net observations report
  48. GRB 251016A: HXMT/HE detection
  49. IceCube-251018A: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  51. GRB 251016A: Swift-XRT afterglow detection
  52. GRB 251017A: Swift/UVOT Detection
  53. GRB 251016A: Swift/UVOT Detection
  54. GRB 251018A: Swift/UVOT Detection
  55. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  56. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  57. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  58. GRB 251016A: VLT/FORS2 Optical Observation
  59. GRB 251017A: COLIBRÍ photometric redshift
  60. GRB 251017A: Swift-XRT refined Analysis
  61. GRB 251018A: MASTER OT detection
  62. GRB 251018A: TRT optical afterglow detection
  63. Swift GRB 251018A: Global MASTER-Net observations report
  64. GRB 251018A: Swift detection of a burst with an optical counterpart
  65. GRB 251018A: Fermi GBM Final Real-time Localization
  66. GRB 251017A: SVOM/VT optical observation
  67. GRB 251011A: Fermi GBM Observation
  68. GRB 251017A: OHP/T193 i-band observations
  69. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  70. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  71. GRB 251017A: J-band detection with WINTER
  72. GRB 251017A: Glowbug gamma-ray detection
  73. GRB 251013C: Liverpool Telescope observations
  74. GRB 251013C: Leavitt Observatory optical photometry
  75. Fermi GRB 251016B: Global MASTER-Net observations report
  76. GRB 251017A: JinShan observations of the optical afterglow
  77. Swift GRB 251017A: Global MASTER-Net observations report
  78. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  79. Swift Trigger 1404295 is not a GRB
  80. GRB 251016A: AstroSat CZTI detection of a short burst
  81. GRB 251017A: Enhanced Swift-XRT position
  82. GRB 251017A: COLIBRÍ Early Afterglow Detection
  83. GRB 251016B: AstroSat CZTI detection
  84. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  85. GRB 251017A: Swift detection of a burst with an optical counterpart
  86. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  88. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  89. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  90. GRB 251007B: Swift-BAT refined analysis
  91. GRB 251016B: Fermi GBM Final Real-time Localization
  92. GRB 251014D: Swift-BAT refined analysis
  93. GRB 251016A: BOOTES-6/DPRT optical upper limit
  94. GRB 251016A: Glowbug gamma-ray detection of a short burst
  95. GRB 251013C: VLA detection
  96. sb25101602: Swift-XRT counterpart detection
  97. Fermi GRB 251016A: Global MASTER-Net observations report
  98. GRB 251016A: Fermi GBM Final Localization
  99. GRB 251016A: SVOM detection of a short burst
  100. GRB 251014A: Swift-XRT observations

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