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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"

19129 results found.

  1. GRB 250911A: MAXI/GSC detection
  2. GRB 251017A: COLIBRÍ optical observations of a late plateau
  3. GRB 251017A: Swift-BAT refined analysis
  4. GRB 251018A: Fermi GBM Observation
  5. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  6. GRB 251018A: Swift-XRT refined Analysis
  7. GRB 251018A: Enhanced Swift-XRT position
  8. GRB 251016A: Swift-XRT afterglow detection
  9. GRB 251017A: Swift/UVOT Detection
  10. GRB 251016A: Swift/UVOT Detection
  11. GRB 251018A: Swift/UVOT Detection
  12. GRB 251016A: VLT/FORS2 Optical Observation
  13. GRB 251017A: COLIBRÍ photometric redshift
  14. GRB 251017A: Swift-XRT refined Analysis
  15. GRB 251018A: MASTER OT detection
  16. GRB 251018A: TRT optical afterglow detection
  17. Swift GRB 251018A: Global MASTER-Net observations report
  18. GRB 251018A: Swift detection of a burst with an optical counterpart
  19. GRB 251017A: SVOM/VT optical observation
  20. GRB 251011A: Fermi GBM Observation
  21. GRB 251017A: Glowbug gamma-ray detection
  22. GRB 251017A: JinShan observations of the optical afterglow
  23. Swift GRB 251017A: Global MASTER-Net observations report
  24. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  25. Swift Trigger 1404295 is not a GRB
  26. GRB 251017A: Enhanced Swift-XRT position
  27. GRB 251017A: COLIBRÍ Early Afterglow Detection
  28. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  29. GRB 251017A: Swift detection of a burst with an optical counterpart
  30. GRB 251007B: Swift-BAT refined analysis
  31. GRB 251014D: Swift-BAT refined analysis
  32. GRB 251016A: BOOTES-6/DPRT optical upper limit
  33. sb25101602: Swift-XRT counterpart detection
  34. GRB 251014A: Swift-XRT observations
  35. GRB 251014B: PRIME J-band upper limit
  36. Swift GRB251015.60: Global MASTER-Net observations report
  37. GRB 251013D: Swift/UVOT Observations
  38. GRB 251013C: Swift/UVOT Detection
  39. Konus-Wind detection of GRB 251007A
  40. GRB 251013D: Swift-XRT observations
  41. Swift Trigger 1404295: possible GRB 251015A
  42. GRB 251014B: Swift-XRT observations
  43. GRB 251014B: Swift/UVOT Upper Limits
  44. GRB 251014B: VLT/FORS2 Optical Observation
  45. GRB 251014D: Swift/UVOT Upper Limits
  46. GRB 251014D: BOOTES-6/DPRT optical upper limit
  47. GRB 251014D: Swift-XRT afterglow detection
  48. GRB 251011B: SVOM/VT optical upper limit
  49. GRB 251013C: Swift ToO observations
  50. GRB 251013D: Fermi GBM Observation
  51. GRB 251014A: Swift-BAT refined analysis
  52. GRB 251014D: Swift detection of a burst
  53. GRB 251014A: PRIME near-infrared upper limits
  54. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  55. GRB 251014A: VLT/FORS2 Optical Observation
  56. GRB 251014B: Swift ToO observations
  57. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  58. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  59. GRB 251013C: Fermi GBM Observation
  60. GRB 251013D: Swift ToO observations
  61. GRB 251014A: DDOTI Upper Limit
  62. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  63. GRB 251014A: SAO RAS optical upper limit
  64. GRB 251014A: Fermi GBM Observation
  65. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  66. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  67. Swift GRB 251014A: Global MASTER-Net observations report
  68. GRB 251014A: Swift detection of a possibly-short burst
  69. GRB 251013C: Swift-XRT counterpart detection
  70. GRB 251003A: Mondy optical upper limit
  71. GRB 251011B inspection: MASTER orphan GRB detection
  72. GRB 251011B: Swift/UVOT Upper Limits
  73. GRB 251011B: SVOM/GRM observation
  74. GRB 251011B: Swift-XRT refined Analysis
  75. GRB 251011B: Fermi GBM Observation
  76. GRB 251011B : MASTER optical observations
  77. GRB 251011B: Enhanced Swift-XRT position
  78. GRB 251011B: Swift detection of a burst
  79. GRB 251007B: Swift/UVOT Upper Limits
  80. GRB251007A: Swift/UVOT Detection
  81. GRB 251007A: Swift-BAT refined analysis
  82. GRB 251007A: SVOM/GRM observation
  83. GRB 251007A: Insight-HXMT detection
  84. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  85. GRB 251006A: Fermi GBM Observation
  86. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  87. GRB 251003A: Fermi GBM Observation
  88. GRB 251007B: COLIBRÍ optical upper limit
  89. GRB 251007A: AstroSat CZTI detection
  90. GRB 250917B: iTelescope T-26 upper limit
  91. GRB 251007A: Swift-XRT refined Analysis
  92. GRB 251007A: Enhanced Swift-XRT position
  93. GRB 251007B: Swift-XRT refined Analysis
  94. GRB 251007B: Enhanced Swift-XRT position
  95. GRB 251007A: AKO Optical Upper Limit
  96. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  97. GRB 251007A: SVOM/C-GFT optical observations
  98. GRB 251005C: PRIME J-band upper limit
  99. Swift GRB 251007B: Global MASTER-Net observations report
  100. GRB 251007A: Glowbug gamma-ray detection

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