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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. LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
  2. GRB 231206A: joint location of multiple instruments by ETJASMIN
  3. GRB 231205B: optical upper limit in TSHAOand AbAO
  4. LIGO/Virgo/KAGRA S231206cc: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S231206ca: Identification of a GW compact binary merger candidate
  6. GRB231115A: TURBO Pre-Burst Optical Upper Limits
  7. GRB 231205B: AGILE detection
  8. Fermi trigger No 723581802: Global MASTER-Net observations report
  9. GRB 231206B: Fermi GBM Final Real-time Localization
  10. GRB 231205B: Ondrejov D50 optical upper limit
  11. GRB 231205B: Swift-XRT refined Analysis
  12. Fermi-LAT gamma-ray observations of IceCube-231202A
  13. GRB 231205B: REM optical/NIR upper limits
  14. GRB 231129C: ASIM MXGS observation and localization
  15. GRB 231205B: NUTTelA-TAO / BSTI Early Optical Limits
  16. GRB 231205B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  17. GRB 231206A: GECAM-B detection of a short burst (correction)
  18. GRB 231205B : MITSuME Akeno optical upper limits
  19. GRB 231206A: GECAM-B detection of a short burst
  20. GRB 231205B: Zadko observatory - Gingin optical observations
  21. GRB 231205B: Gaoyazi/GOT optical upper limit
  22. GRB 231205B: Nanshan/HMT optical upper limit
  23. GRB 231205B: GECAM-B detection of a long burst
  24. GRB 231205B: LCOGT Optical Upper Limits
  25. GRB 231205A: DDOTI Upper Limits on the Afterglow
  26. LIGO/Virgo/KAGRA S231205c: One counterpart neutrino candidate event from an IceCube neutrino search
  27. GRB 231205B: Enhanced Swift-XRT position
  28. GRB 231204A: Glowbug gamma-ray detection
  29. Swift GRB231205.70: Global MASTER-Net observations report
  30. GRB 231204A: CALET Gamma-Ray Burst Monitor detection
  31. Fermi-LAT daily aperture light curve of T CrB now available
  32. GRB 231205B: AKO Optical Upper Limit
  33. GRB 231205B: Swift detection of a burst
  34. GRB 231205A: joint location of multiple instruments by ETJASMIN
  35. GRB 231204A: AstroSat CZTI detection
  36. GRB 231205A: GECAM-B detection of a short burst
  37. Fermi trigger No 723435916: Global MASTER-Net observations report
  38. Fermi trigger No 723326169: Global MASTER-Net observations report
  39. GRB 231205A: Fermi GBM Final Real-time Localization
  40. LIGO/Virgo/KAGRA S231129ac: Upper limits from Swift/BAT-GUANO
  41. IceCube-231202A: Upper limits from a search for additional neutrino events in IceCube
  42. Fermi trigger No 723412808: Global MASTER-Net observations report
  43. GRB 231203A: Fermi GBM Observation
  44. GRB 231204A: Fermi GBM Final Real-time Localization
  45. GRB 231203A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  46. Konus-Wind detection of GRB 231129C
  47. IceCube-231202A - IceCube observation of a high-energy neutrino candidate track-like event
  48. Fermi trigger No 723279695: Global MASTER-Net observations report
  49. The Fermi GBM team reports the detection of a likely SHORT GRB
  50. GRB 231203A: Fermi GBM Final Real-time Localization
  51. GRB 231129C: Swift-XRT afterglow detection
  52. Fermi trigger No 723149952: Global MASTER-Net observations report
  53. GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate
  54. GRB 231129A: VZLUSAT-2 detection
  55. GRB 231129B: Swift-XRT observations
  56. GRB 231128A: VZLUSAT-2 detection
  57. Optical transient in the field of Messier 31, likely a new blazar: back to bright state
  58. GRB 231129C: AGILE detection
  59. GRB 231129A : MITSuME Akeno optical upper limits
  60. GRB 231129C: Swift/BAT-GUANO localization of a burst outside the coded FOV
  61. GRB 231129A: Swift-BAT refined analysis
  62. GRB 231129C: MASTER OT detection
  63. GRB 231129A: BOOTES-5/JGT optical upper limit
  64. GRB 231129C: Fermi-LAT detection
  65. GRB 231129A: JinShan optical upper limit
  66. GRB 231129C: GRBAlpha detection
  67. GRB 231129C: Glowbug gamma-ray detection
  68. GRB 231129C: Swift-XRT observations
  69. GRB 231129A: Swift/UVOT Upper Limits
  70. GRB 231129A: optical upper limit in Mondy observatory
  71. GRB 231129C: GECAM-B detection of a bright burst
  72. GRB 231129C: AstroSat CZTI detection
  73. GRB 231129C: iTelescope OT retraction
  74. GRB 231129C: CALET Gamma-Ray Burst Monitor detection
  75. GRB 231129C: Fermi GBM Observation of a very bright GRB
  76. GRB 231129C: iTelescope likely optical afterglow AT 2023yph discovery
  77. GRB 231129C: Tiled Swift observations
  78. GRB 231127A: GRBAlpha detection
  79. GRB 231129C: MAXI/GSC detection
  80. GRB 231129C: BALROG localization (Fermi Trigger / GRB 231129799)
  81. GRB 231129C: Fermi GBM detection of a very bright burst
  82. GRB 231129A: Enhanced Swift-XRT position
  83. LIGO/Virgo/KAGRA S231129ac: Updated Sky localization
  84. GRB 231129A: Swift-XRT refined Analysis
  85. GRB 231129C: Fermi GBM Final Real-time Localization
  86. Fermi trigger No 722977823: Global MASTER-Net observations report
  87. GRB 231129B: Tiled Swift observations
  88. GRB 231129B: MAXI/GSC detection
  89. Fermi-LAT gamma-ray observations of IceCube-231125A
  90. Integral GRB231129.21: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
  92. GRB 231129A: GECAM-C detection of a long burst
  93. GRB 231129A: INTEGRAL detection of a long GRB
  94. GRB 231129A: Swift detection of a burst
  95. LIGO/Virgo/KAGRA S231127cg: Updated Sky localization
  96. GRB 231128A: Fermi GBM Final Real-time Localization
  97. GRB 231123C: Fermi GBM Observation
  98. GRB 231123B: Fermi GBM Observation
  99. IceCube-231125A: Upper limits from a search for additional neutrino events in IceCube
  100. LIGO/Virgo/KAGRA S231127cg: Identification of a GW compact binary merger candidate

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