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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 251013C: further SAO RAS optical observations
  2. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  3. GRB 251022A: COLIBRÍ optical observations
  4. GRB 251013C: ISON-Castelgrande observatory optical observations
  5. GRB 251022A: MASTER OT detection
  6. GRB 251022A: DDOTI Optical Detection
  7. EP251021b/GRB 251021A: SVOM/VT optical candidate
  8. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  9. EP251023a: NOT optical counterpart detection
  10. Fermi GRB 251023A: Global MASTER-Net observations report
  11. EP251023a: GSP Optical Counterpart Detection
  12. EP251023a: Einstein Probe detection of an X-ray transient
  13. EP/WXT 01709247295: GOTO optical afterglow candidate.
  14. GRB 251022A: GOTO optical counterpart detection
  15. GRB 251023A: Fermi GBM Final Localization Correction
  16. GRB 251022A: Fermi-LAT detection
  17. GRB 251016B: Fermi GBM Detection
  18. GRB 251022A: Tiled Swift observations
  19. LAT GRB251022A: Global MASTER-Net observations report
  20. GRB 251022A: Fermi GBM Final Real-time Localization
  21. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  22. EP251021b: BOOTES-7 optical upper limit
  23. EP251021b: Einstein Probe detection of a fast X-ray transient
  24. GRB 250911A: MAXI/GSC detection
  25. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  26. GRB 251016A: SVOM/ECLAIRs refined analysis
  27. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  29. Fermi-LAT gamma-ray observations of IceCube-251018A
  30. GRB 251017A : RAPAS follow-up observations
  31. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 251017A: COLIBRÍ optical observations of a late plateau
  33. IceCube-251018A: DDOTI Optical Upper Limit
  34. GRB 251017A: Swift-BAT refined analysis
  35. GRB 251016A: Fermi GBM Observation
  36. GRB 251018A: Fermi GBM Observation
  37. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  38. GRB 251018A: Swift-XRT refined Analysis
  39. GRB 251018A: Enhanced Swift-XRT position
  40. Fermi trigger No 782500909: Global MASTER-Net observations report
  41. GRB 251016A: HXMT/HE detection
  42. IceCube-251018A: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  44. GRB 251016A: Swift-XRT afterglow detection
  45. GRB 251017A: Swift/UVOT Detection
  46. GRB 251016A: Swift/UVOT Detection
  47. GRB 251018A: Swift/UVOT Detection
  48. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  49. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  50. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  51. GRB 251016A: VLT/FORS2 Optical Observation
  52. GRB 251017A: COLIBRÍ photometric redshift
  53. GRB 251017A: Swift-XRT refined Analysis
  54. GRB 251018A: MASTER OT detection
  55. GRB 251018A: TRT optical afterglow detection
  56. Swift GRB 251018A: Global MASTER-Net observations report
  57. GRB 251018A: Swift detection of a burst with an optical counterpart
  58. GRB 251018A: Fermi GBM Final Real-time Localization
  59. GRB 251017A: SVOM/VT optical observation
  60. GRB 251011A: Fermi GBM Observation
  61. GRB 251017A: OHP/T193 i-band observations
  62. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  63. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  64. GRB 251017A: J-band detection with WINTER
  65. GRB 251017A: Glowbug gamma-ray detection
  66. GRB 251013C: Liverpool Telescope observations
  67. GRB 251013C: Leavitt Observatory optical photometry
  68. Fermi GRB 251016B: Global MASTER-Net observations report
  69. GRB 251017A: JinShan observations of the optical afterglow
  70. Swift GRB 251017A: Global MASTER-Net observations report
  71. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  72. Swift Trigger 1404295 is not a GRB
  73. GRB 251016A: AstroSat CZTI detection of a short burst
  74. GRB 251017A: Enhanced Swift-XRT position
  75. GRB 251017A: COLIBRÍ Early Afterglow Detection
  76. GRB 251016B: AstroSat CZTI detection
  77. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  78. GRB 251017A: Swift detection of a burst with an optical counterpart
  79. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  80. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  81. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  82. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  83. GRB 251007B: Swift-BAT refined analysis
  84. GRB 251016B: Fermi GBM Final Real-time Localization
  85. GRB 251014D: Swift-BAT refined analysis
  86. GRB 251016A: BOOTES-6/DPRT optical upper limit
  87. GRB 251016A: Glowbug gamma-ray detection of a short burst
  88. GRB 251013C: VLA detection
  89. sb25101602: Swift-XRT counterpart detection
  90. Fermi GRB 251016A: Global MASTER-Net observations report
  91. GRB 251016A: Fermi GBM Final Localization
  92. GRB 251016A: SVOM detection of a short burst
  93. GRB 251014A: Swift-XRT observations
  94. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  95. GRB 251014B: PRIME J-band upper limit
  96. Upper limits from a search for additional neutrino events in IceCube
  97. IceCube Alert 251014.77: Global MASTER-Net observations report
  98. Swift GRB251015.60: Global MASTER-Net observations report
  99. GRB 251013C: Kilonova-Catcher optical afterglow detection
  100. Fermi-LAT Gamma-ray Observations of IceCube-251014A

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