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"

32501 results found.

  1. Fermi GRB 251026B: Global MASTER-Net observations report
  2. Fermi GRB 251025C: Global MASTER-Net observations report
  3. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  4. GRB 251026A: Swift-XRT observations
  5. GRB 251025B: OHP/T193 optical detection
  6. GRB 251025B: J-band detection with WINTER
  7. GRB 251026A: SVOM/C-GFT upper limit
  8. IceCube-251025A: DDOTI Optical Upper Limit
  9. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. GRB 251025B: SVOM/VT optical bump
  11. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  12. GRB 251023A: SVOM/GRM observation
  13. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  14. Konus-Wind detection of GRB 251016B
  15. GRB 251025B: GROWTH-India Telescope optical observations
  16. GRB 251024A: Swift/UVOT Upper Limits
  17. GRB 251025B: Swift-XRT afterglow detection
  18. GRB 251024A: Swift-BAT refined analysis
  19. GRB 251025A (sb25102501): stellar flare confirmed
  20. GRB 251025B: SVOM/VT optical observations with VHF data
  21. GRB 251025B: MASTER OT detection
  22. GRB 251025B: SVOM/C-GFT optical counterpart detection
  23. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  24. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  25. GRB 251025A: SVOM/VT VHF optical upper limit
  26. GRB 251003A: VLA Detection
  27. GRB 251023C: Glowbug gamma-ray detection
  28. GRB 251024A: LCOGT Optical Afterglow Detection
  29. GRB 251022A: KAIT optical observations
  30. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  31. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  32. EP251023a: MAO/AZT-22 optical observations
  33. GRB 251023B: OHP/T193 optical observations
  34. EP251023a: OHP/T193 optical observations
  35. GRB 251023C: AstroSat CZTI detection
  36. EP251023b/GRB 251023B: JinShan optical observation
  37. GRB 251022A: Swift-XRT detection of GOTO25iym
  38. EP251023b: Global MASTER-Net observations report
  39. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  40. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  41. GRB 251022A: GROWTH-India Telescope optical observations
  42. EP251023a: GROWTH-India Telescope optical observations
  43. GRB 251022A: Fermi GBM Observation
  44. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  45. GRB 251023A: Glowbug gamma-ray detection
  46. GRB 251023B: Glowbug gamma-ray detection
  47. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  48. EP251023a: Global MASTER-Net observations report
  49. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  50. IPN triangulation of GRB 251016B
  51. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  52. EP#01709247298: Swift-XRT counterpart detection
  53. EP251023a: COLIBRÍ optical observations
  54. GRB 251013C: further SAO RAS optical observations
  55. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  56. GRB 251022A: COLIBRÍ optical observations
  57. GRB 251013C: ISON-Castelgrande observatory optical observations
  58. GRB 251022A: MASTER OT detection
  59. GRB 251022A: DDOTI Optical Detection
  60. EP251021b/GRB 251021A: SVOM/VT optical candidate
  61. EP251023a: NOT optical counterpart detection
  62. Fermi GRB 251023A: Global MASTER-Net observations report
  63. EP251023a: GSP Optical Counterpart Detection
  64. EP251023a: Einstein Probe detection of an X-ray transient
  65. GRB 251022A: GOTO optical counterpart detection
  66. GRB 251022A: Fermi-LAT detection
  67. GRB 251022A: Tiled Swift observations
  68. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  69. EP251021b: BOOTES-7 optical upper limit
  70. GRB 250911A: MAXI/GSC detection
  71. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  72. GRB 251016A: SVOM/ECLAIRs refined analysis
  73. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  75. Fermi-LAT gamma-ray observations of IceCube-251018A
  76. GRB 251017A : RAPAS follow-up observations
  77. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 251017A: COLIBRÍ optical observations of a late plateau
  79. IceCube-251018A: DDOTI Optical Upper Limit
  80. GRB 251017A: Swift-BAT refined analysis
  81. GRB 251016A: Fermi GBM Observation
  82. GRB 251018A: Fermi GBM Observation
  83. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  84. GRB 251016A: HXMT/HE detection
  85. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  86. GRB 251017A: Swift/UVOT Detection
  87. GRB 251016A: Swift/UVOT Detection
  88. GRB 251018A: Swift/UVOT Detection
  89. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  90. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  91. GRB 251016A: VLT/FORS2 Optical Observation
  92. GRB 251017A: COLIBRÍ photometric redshift
  93. GRB 251018A: MASTER OT detection
  94. GRB 251018A: TRT optical afterglow detection
  95. Swift GRB 251018A: Global MASTER-Net observations report
  96. GRB 251017A: SVOM/VT optical observation
  97. GRB 251011A: Fermi GBM Observation
  98. GRB 251017A: OHP/T193 i-band observations
  99. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  100. GRB 251017A: J-band detection with WINTER

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov