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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"

21791 results found.

  1. GRB 251022A: MASTER OT detection
  2. GRB 251022A: DDOTI Optical Detection
  3. Fermi GRB 251023A: Global MASTER-Net observations report
  4. EP251023a: GSP Optical Counterpart Detection
  5. EP/WXT 01709247295: GOTO optical afterglow candidate.
  6. GRB 251022A: GOTO optical counterpart detection
  7. GRB 251022A: Tiled Swift observations
  8. LAT GRB251022A: Global MASTER-Net observations report
  9. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  10. GRB 251016A: SVOM/ECLAIRs refined analysis
  11. Fermi-LAT gamma-ray observations of IceCube-251018A
  12. GRB 251017A : RAPAS follow-up observations
  13. GRB 251017A: COLIBRÍ optical observations of a late plateau
  14. IceCube-251018A: DDOTI Optical Upper Limit
  15. Fermi trigger No 782500909: Global MASTER-Net observations report
  16. IceCube-251018A: Global MASTER-Net observations report
  17. GRB 251016A: Swift-XRT afterglow detection
  18. GRB 251017A: Swift/UVOT Detection
  19. GRB 251016A: Swift/UVOT Detection
  20. GRB 251018A: Swift/UVOT Detection
  21. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 251016A: VLT/FORS2 Optical Observation
  23. GRB 251017A: COLIBRÍ photometric redshift
  24. GRB 251018A: TRT optical afterglow detection
  25. Swift GRB 251018A: Global MASTER-Net observations report
  26. GRB 251017A: OHP/T193 i-band observations
  27. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  28. GRB 251017A: J-band detection with WINTER
  29. GRB 251013C: Liverpool Telescope observations
  30. GRB 251013C: Leavitt Observatory optical photometry
  31. Fermi GRB 251016B: Global MASTER-Net observations report
  32. GRB 251017A: JinShan observations of the optical afterglow
  33. Swift GRB 251017A: Global MASTER-Net observations report
  34. GRB 251017A: COLIBRÍ Early Afterglow Detection
  35. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  36. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  37. GRB 251013C: VLA detection
  38. sb25101602: Swift-XRT counterpart detection
  39. Fermi GRB 251016A: Global MASTER-Net observations report
  40. GRB 251014A: Swift-XRT observations
  41. GRB 251014B: PRIME J-band upper limit
  42. IceCube Alert 251014.77: Global MASTER-Net observations report
  43. Swift GRB251015.60: Global MASTER-Net observations report
  44. GRB 251013C: Kilonova-Catcher optical afterglow detection
  45. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  46. GRB 251013D: Swift/UVOT Observations
  47. GRB 251013C: Swift/UVOT Detection
  48. GRB 251013C: detection of a radio counterpart at 15.5GHz
  49. GRB 251013C: SVOM/ECLAIRs refined analysis
  50. GRB 251013D: Swift-XRT observations
  51. GRB 251014B: Swift-XRT observations
  52. GRB 251014B: Swift/UVOT Upper Limits
  53. GRB 251014B: VLT/FORS2 Optical Observation
  54. GRB 251014D: Swift/UVOT Upper Limits
  55. GRB 251014D: Swift-XRT afterglow detection
  56. GRB 251013C: MAO/AZT-22 optical observations
  57. GRB 251013C: Swift ToO observations
  58. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  59. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  60. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  61. GRB 251014A: PRIME near-infrared upper limits
  62. GRB 251014A: VLT/FORS2 Optical Observation
  63. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  64. GRB 251013C: MarSEC, optical afterglow photometry
  65. GRB 251014B: Swift ToO observations
  66. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  67. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  68. GRB 251013C: Bassano Bresciano Observatory optical observations
  69. GRB 251013C: Early and late-time optical counterpart detection by LCO
  70. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  71. GRB 251013D: Swift ToO observations
  72. GRB 251014A: DDOTI Upper Limit
  73. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  74. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  75. GRB 251013C: Asiago optical observations
  76. GRB 251013C: ABObservatory optical observations
  77. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  78. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  79. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  80. GRB 251013C: ALMA detection
  81. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  82. GRB 251013C: DDOTI detection of the optical afterglow
  83. GRB 251013C: SLKT optical afterglow photometry
  84. Swift GRB 251014A: Global MASTER-Net observations report
  85. Fermi trigger No 782044789: Global MASTER-Net observations report
  86. Fermi GRB 251013C: Global MASTER-Net observations report
  87. Fermi GRB 251013B: Global MASTER-Net observations report
  88. Fermi GRB 251013D: Global MASTER-Net observations report
  89. GRB 251013C: Swift-XRT counterpart detection
  90. GRB 251013C: GOTO optical afterglow detection
  91. GRB 251013C: SAO RAS optical observations
  92. GRB 251013C: LCO optical afterglow detection
  93. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  94. GRB 251013C: LAST detection of optical counterpart
  95. GRB 251003A: Mondy optical upper limit
  96. Fermi GRB 251013A: Global MASTER-Net observations report
  97. GRB 251011B inspection: MASTER orphan GRB detection
  98. GRB 251011B: Swift/UVOT Upper Limits
  99. Fermi GRB 251011A: Global MASTER-Net observations report
  100. GRB 251011B : MASTER optical observations

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