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"
  1. GRB 251017A : RAPAS follow-up observations
  2. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 251017A: COLIBRÍ optical observations of a late plateau
  4. IceCube-251018A: DDOTI Optical Upper Limit
  5. GRB 251017A: Swift-BAT refined analysis
  6. GRB 251016A: Fermi GBM Observation
  7. GRB 251018A: Fermi GBM Observation
  8. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  9. GRB 251018A: Swift-XRT refined Analysis
  10. GRB 251018A: Enhanced Swift-XRT position
  11. Fermi trigger No 782500909: Global MASTER-Net observations report
  12. GRB 251016A: HXMT/HE detection
  13. IceCube-251018A: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  15. GRB 251016A: Swift-XRT afterglow detection
  16. GRB 251017A: Swift/UVOT Detection
  17. GRB 251016A: Swift/UVOT Detection
  18. GRB 251018A: Swift/UVOT Detection
  19. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  20. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  21. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  22. GRB 251016A: VLT/FORS2 Optical Observation
  23. GRB 251017A: COLIBRÍ photometric redshift
  24. GRB 251017A: Swift-XRT refined Analysis
  25. GRB 251018A: MASTER OT detection
  26. GRB 251018A: TRT optical afterglow detection
  27. Swift GRB 251018A: Global MASTER-Net observations report
  28. GRB 251018A: Swift detection of a burst with an optical counterpart
  29. GRB 251018A: Fermi GBM Final Real-time Localization
  30. GRB 251017A: SVOM/VT optical observation
  31. GRB 251011A: Fermi GBM Observation
  32. GRB 251017A: OHP/T193 i-band observations
  33. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  34. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  35. GRB 251017A: J-band detection with WINTER
  36. GRB 251017A: Glowbug gamma-ray detection
  37. GRB 251013C: Liverpool Telescope observations
  38. GRB 251013C: Leavitt Observatory optical photometry
  39. Fermi GRB 251016B: Global MASTER-Net observations report
  40. GRB 251017A: JinShan observations of the optical afterglow
  41. Swift GRB 251017A: Global MASTER-Net observations report
  42. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  43. Swift Trigger 1404295 is not a GRB
  44. GRB 251016A: AstroSat CZTI detection of a short burst
  45. GRB 251017A: Enhanced Swift-XRT position
  46. GRB 251017A: COLIBRÍ Early Afterglow Detection
  47. GRB 251016B: AstroSat CZTI detection
  48. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  49. GRB 251017A: Swift detection of a burst with an optical counterpart
  50. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  51. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  52. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  53. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  54. GRB 251007B: Swift-BAT refined analysis
  55. GRB 251016B: Fermi GBM Final Real-time Localization
  56. GRB 251014D: Swift-BAT refined analysis
  57. GRB 251016A: BOOTES-6/DPRT optical upper limit
  58. GRB 251016A: Glowbug gamma-ray detection of a short burst
  59. GRB 251013C: VLA detection
  60. sb25101602: Swift-XRT counterpart detection
  61. Fermi GRB 251016A: Global MASTER-Net observations report
  62. GRB 251016A: Fermi GBM Final Localization
  63. GRB 251016A: SVOM detection of a short burst
  64. GRB 251014A: Swift-XRT observations
  65. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  66. GRB 251014B: PRIME J-band upper limit
  67. Upper limits from a search for additional neutrino events in IceCube
  68. IceCube Alert 251014.77: Global MASTER-Net observations report
  69. Swift GRB251015.60: Global MASTER-Net observations report
  70. GRB 251013C: Kilonova-Catcher optical afterglow detection
  71. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  72. GRB 251013D: Swift/UVOT Observations
  73. GRB 251013C: Swift/UVOT Detection
  74. Konus-Wind detection of GRB 251007A
  75. Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB
  76. GRB 251013C, GCN Circular 42267, errata corrige
  77. GRB 251013C: detection of a radio counterpart at 15.5GHz
  78. GRB 251015A: Fermi GBM Final Real-time Localization
  79. GRB 251013C: SVOM/ECLAIRs refined analysis
  80. GRB 251013D: Swift-XRT observations
  81. Swift Trigger 1404295: possible GRB 251015A
  82. GRB 251014B: Swift-XRT observations
  83. GRB 251014B: Swift/UVOT Upper Limits
  84. GRB 251014B: VLT/FORS2 Optical Observation
  85. GRB 251014D: Swift/UVOT Upper Limits
  86. GRB 251014D: BOOTES-6/DPRT optical upper limit
  87. GRB 251014D: Swift-XRT afterglow detection
  88. GRB 251013C: MAO/AZT-22 optical observations
  89. GRB 251011B: SVOM/VT optical upper limit
  90. GRB 251013C: Swift ToO observations
  91. GRB 251013D: Fermi GBM Observation
  92. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  93. GRB 251014A: Swift-BAT refined analysis
  94. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  95. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  96. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  97. GRB 251014D: Swift detection of a burst
  98. GRB 251014A: PRIME near-infrared upper limits
  99. GRB 251014C: Fermi GBM Final Localization
  100. GRB 251014A: Glowbug gamma-ray detection of a likely short burst

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