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 251226A: Glowbug gamma-ray detection
  2. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  3. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  4. Fermi GRB 251228A: Global MASTER-Net observations report
  5. The EP-WXT trigger 01709250662 is likely a flaring star
  6. GRB 251228A: Fermi GBM Final Real-time Localization
  7. GRB 251226A: SVOM/GRM observation
  8. GRB 251226A: GECAM-B detection
  9. SVOM GRB251227.07: Global MASTER-Net observations report
  10. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  11. The EP-WXT trigger 01709250617 is likely a flaring star
  12. IceCube Alert 251225.84: Global MASTER-Net observations report
  13. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  14. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  15. GRB 251222A: NUTTelA-TAO Early Measurements
  16. GRB 251222A/EP251222b: Optical detection with Kinder observations
  17. EP251222a: Optical upper limit with Kinder observations
  18. GRB 251221A: Swift-BAT refined analysis
  19. GRB 251222A/EP251222b: FTW optical and NIR observations
  20. EP251222a: FTW optical and NIR observations
  21. GRB 251205A: Kilonova-Catcher optical afterglow detection
  22. GRB 251222A: AbAO optical observations
  23. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  24. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  25. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  26. GRB 251222A: ZTSH BVRI optical observations
  27. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. GRB 251222A: Continued 1.3m DFOT optical observation
  29. EP251220a: 3.6m DOT optical afterglow detection
  30. GRB 251222A: Fermi GBM Observation
  31. EP251220a: CrAO ZTSh optical observations
  32. EP251221a: PRIME upper limit
  33. EP251222a: Global MASTER-Net observations report
  34. GRB 251222A / EP251222b: GECAM-B observation
  35. EP251221a: Liverpool Telescope upper limits
  36. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  38. Konus-Wind detection of GRB 251222A / EP251222b
  39. GRB 251222A: Swift-XRT afterglow detection
  40. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  41. EP251222a: NTT/ULTRACAM optical observations
  42. EP251222a: GOTO optical upper limit
  43. GRB 251222A / EP251222b: GOTO optical counterpart detection
  44. GRB 251222A / EP251222b: LCO optical observations
  45. GRB 251222A: 1.3m DFOT optical detection
  46. GRB251221A: 7DT optical upper limits
  47. EP251222a: GSP Optical Counterpart Detection
  48. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  49. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  50. EP251222b/GRB 251222A: SVOM/GRM observation
  51. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  52. EP251222a: Einstein Probe detection of an X-ray transient
  53. The EP-WXT trigger 01709250397 is likely a flaring star
  54. EP251221a: Global MASTER-Net observations report
  55. GRB 251222A: PRIME near-infrared detection
  56. EP251221a: NOT optical upper limit
  57. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  58. GRB 251222A: NOT optical observations
  59. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  60. IPN triangulation of GRB 251220B (short)
  61. GRB 251222A: Swift ToO observations
  62. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  63. GRB 251222A: SVOM/VT optical candidate
  64. GRB 251222A: SVOM detection of a long burst
  65. SVOM GRB251222A: Global MASTER-Net observations report
  66. GRB 251222A: Fermi GBM Final Real-time Localization
  67. EP251220a: PRIME upper limit
  68. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  69. GRB 251221A: PRIME near-infrared observation
  70. EP251220a: NOT optical observations
  71. EP251220a: FTW optical and NIR observations
  72. GRB 251221A: UAFO and Mondy optical upper limit
  73. GRB 251221A: Swift-XRT refined Analysis
  74. EP251221a: Einstein Probe detection of a fast X-ray transient
  75. GRB 251221A: Swift/UVOT Upper Limits
  76. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  77. GRB 251221A: Enhanced Swift-XRT position
  78. GRB 251221A: Fermi GBM Observation
  79. GRB 251221B: Fermi GBM Final Real-time Localization
  80. EP251220a: EP-FXT follow-up observation
  81. GRB 251220B: SVOM/GRM observation of a short burst
  82. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  83. EP 251220a: GOTO optical counterpart detection
  84. GRB 251221A: COLIBRÍ detection of the optical counterpart
  85. EP 251220a: COLIBRÍ detection of the optical counterpart
  86. GRB 251221A: Swift detection of a burst
  87. Swift GRB251221A: Global MASTER-Net observations report
  88. GRB 251221A: Fermi GBM Final Real-time Localization
  89. EP251220a: Global MASTER-Net observations report
  90. EP251220a: EP detection of a fast X-ray transient
  91. SVOM GRB251220.98: Global MASTER-Net observations report
  92. GRB 251220B: Fermi GBM Final Real-time Localization
  93. GRB 251219A: SVOM/GRM observation of a short burst
  94. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  95. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  96. GRB 251220A: MAXI/GSC detection
  97. GRB 251215A: Swift-XRT afterglow detection
  98. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-251218A: COLIBRÍ optical upper limits
  100. SVOM GRB251219.11: Global MASTER-Net observations report

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