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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 251018A: MASTER OT detection
  2. GRB 251018A: TRT optical afterglow detection
  3. Swift GRB 251018A: Global MASTER-Net observations report
  4. GRB 251018A: Swift detection of a burst with an optical counterpart
  5. GRB 251018A: Fermi GBM Final Real-time Localization
  6. GRB 251017A: SVOM/VT optical observation
  7. GRB 251011A: Fermi GBM Observation
  8. GRB 251017A: OHP/T193 i-band observations
  9. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  10. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  11. GRB 251017A: J-band detection with WINTER
  12. GRB 251017A: Glowbug gamma-ray detection
  13. GRB 251013C: Liverpool Telescope observations
  14. GRB 251013C: Leavitt Observatory optical photometry
  15. Fermi GRB 251016B: Global MASTER-Net observations report
  16. GRB 251017A: JinShan observations of the optical afterglow
  17. Swift GRB 251017A: Global MASTER-Net observations report
  18. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  19. Swift Trigger 1404295 is not a GRB
  20. GRB 251016A: AstroSat CZTI detection of a short burst
  21. GRB 251017A: Enhanced Swift-XRT position
  22. GRB 251017A: COLIBRÍ Early Afterglow Detection
  23. GRB 251016B: AstroSat CZTI detection
  24. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  25. GRB 251017A: Swift detection of a burst with an optical counterpart
  26. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  27. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  28. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  29. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  30. GRB 251007B: Swift-BAT refined analysis
  31. GRB 251016B: Fermi GBM Final Real-time Localization
  32. GRB 251014D: Swift-BAT refined analysis
  33. GRB 251016A: BOOTES-6/DPRT optical upper limit
  34. GRB 251016A: Glowbug gamma-ray detection of a short burst
  35. GRB 251013C: VLA detection
  36. sb25101602: Swift-XRT counterpart detection
  37. Fermi GRB 251016A: Global MASTER-Net observations report
  38. GRB 251016A: Fermi GBM Final Localization
  39. GRB 251016A: SVOM detection of a short burst
  40. GRB 251014A: Swift-XRT observations
  41. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  42. GRB 251014B: PRIME J-band upper limit
  43. Upper limits from a search for additional neutrino events in IceCube
  44. IceCube Alert 251014.77: Global MASTER-Net observations report
  45. Swift GRB251015.60: Global MASTER-Net observations report
  46. GRB 251013C: Kilonova-Catcher optical afterglow detection
  47. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  48. GRB 251013D: Swift/UVOT Observations
  49. GRB 251013C: Swift/UVOT Detection
  50. Konus-Wind detection of GRB 251007A
  51. Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB
  52. GRB 251013C, GCN Circular 42267, errata corrige
  53. GRB 251013C: detection of a radio counterpart at 15.5GHz
  54. GRB 251015A: Fermi GBM Final Real-time Localization
  55. GRB 251013C: SVOM/ECLAIRs refined analysis
  56. GRB 251013D: Swift-XRT observations
  57. Swift Trigger 1404295: possible GRB 251015A
  58. GRB 251014B: Swift-XRT observations
  59. GRB 251014B: Swift/UVOT Upper Limits
  60. GRB 251014B: VLT/FORS2 Optical Observation
  61. GRB 251014D: Swift/UVOT Upper Limits
  62. GRB 251014D: BOOTES-6/DPRT optical upper limit
  63. GRB 251014D: Swift-XRT afterglow detection
  64. GRB 251013C: MAO/AZT-22 optical observations
  65. GRB 251011B: SVOM/VT optical upper limit
  66. GRB 251013C: Swift ToO observations
  67. GRB 251013D: Fermi GBM Observation
  68. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  69. GRB 251014A: Swift-BAT refined analysis
  70. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  72. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  73. GRB 251014D: Swift detection of a burst
  74. GRB 251014A: PRIME near-infrared upper limits
  75. GRB 251014C: Fermi GBM Final Localization
  76. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  77. GRB 251014A: VLT/FORS2 Optical Observation
  78. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  79. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  80. GRB 251013C: MarSEC, optical afterglow photometry
  81. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  82. GRB 251014B: Swift ToO observations
  83. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  84. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  85. GRB 251013C: Bassano Bresciano Observatory optical observations
  86. GRB 251013C: Early and late-time optical counterpart detection by LCO
  87. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  88. GRB 251013C: Fermi GBM Observation
  89. GRB 251013D: Swift ToO observations
  90. GRB 251014A: DDOTI Upper Limit
  91. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  92. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  93. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  94. GRB 251013C: Asiago optical observations
  95. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  96. GRB 251013C: ABObservatory optical observations
  97. GRB 251014A: SAO RAS optical upper limit
  98. GRB 251014A: Fermi GBM Observation
  99. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  100. GRB 251013C: EP-FXT counterpart detection

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