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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"

27774 results found.

  1. GRB 240916A: Swift-XRT afterglow detection
  2. GRB 240916A: Swift ToO observations
  3. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  4. GRB 240916B: Fermi GBM Final Real-time Localization
  5. GRB 240914B: Fermi GBM Final Localization
  6. GRB 240916A: Fermi GBM Final Real-time Localization
  7. EP240913a/GRB 240913C: KAIT optical upper limit
  8. GRB 240913C: Fermi GBM detection
  9. GRB 240914A: Swift-XRT observations
  10. GRB 240914B: AstroSat CZTI detection
  11. EP240913A / GRB 240913C: AstroSat CZTI detection
  12. GRB 240914A: Swift ToO observations
  13. EP240913a: ESO-NTT optical observations
  14. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  15. GRB 240905E: further NOT optical observations
  16. EP240913a: EP-WXT detection of a fast X-ray transient
  17. GRB 240913B: Fermi GBM Final Real-time Localization
  18. GRB 240911A: LCO optical observations
  19. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  20. GRB 240912A: Swift/UVOT Detection
  21. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  22. GRB 240912A: SVOM/GRM observation
  23. GRB 240911A: Swift-XRT observations
  24. GRB 240913A: Fermi GBM Final Real-time Localization
  25. GRB 240912A: J-band observations with WINTER
  26. GRB 240912A: Swift-XRT refined Analysis
  27. GRB 240912A: Fermi GBM Observation
  28. Swift GRB 240912A: Global MASTER-Net observations report
  29. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  30. GRB 240911A: Tiled Swift observations
  31. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  32. GRB 240912B: Fermi GBM Final Real-time Localization
  33. GRB 240912A: NOT optical spectroscopy
  34. GRB 240912A: Enhanced Swift-XRT position
  35. GRB 240912A: Swift detection of a burst with an optical counterpart
  36. GRB 240912A: Fermi GBM Final Real-time Localization
  37. GRB 240910A: Fermi GBM Observation
  38. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  39. GRB 240910A: JinShan optical observations
  40. GRB 240910A: GOTO candidate optical counterpart
  41. EP240908a: Optical afterglow confirmation
  42. GRB 240910A: Swift ToO observations
  43. IPN triangulation of GRB 240905B (short)
  44. GRB 240825A: 7DT Optical Upper Limit
  45. GRB 240905E: SVOM/VT optical observations
  46. GRB 240910A: GRBAlpha detection
  47. GRB 240910B: Fermi GBM Final Real-time Localization
  48. EP240908a: Updates on the WXT detection result around the trigger time
  49. GRB 240910A: Fermi GBM Final Real-time Localization
  50. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  51. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  52. EP240908a: optical afterglow candidate
  53. GRB 240905B: GOTO optical upper limits
  54. EP240908a: EP detection of a fast X-ray transient
  55. GRB 240908A: Fermi GBM Final Real-time Localization
  56. GRB 240905E: GIT optical upper limit
  57. GRB 240905B: Swift-XRT observations
  58. GRB 240905E: Gaoyazi/GOT optical upper limits
  59. GRB 240905B: Fermi-LAT detection
  60. GRB 240905B: Swift ToO observations
  61. GRB 240905E: J-band observations with WINTER
  62. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  63. GRB 240905E: AKO Optical Upper Limit
  64. GRB 240905E: SVOM/C-GFT optical upper limit
  65. GRB 240905E: NOT optical upper limits
  66. GRB 240905E: REM optical/NIR upper limits
  67. GRB 240902B: AstroSat CZTI detection of a long burst
  68. GRB 240905E: Swift-XRT refined Analysis
  69. GRB 240902A: AstroSat CZTI detection of a long burst
  70. GRB 240905E: SVOM/GRM observation
  71. GRB 240905E: LCOGT Optical Upper Limit
  72. GRB 240905E: Swift/UVOT Upper Limits
  73. GRB 240905E: SAO RAS optical upper limit
  74. GRB 240905E: Nanshan/HMT optical upper limit
  75. Swift GRB 240905E: Global MASTER-Net observations report
  76. GRB 240905E: Swift detection of a burst
  77. GRB 240819A: Optical upper limits from TESS
  78. GRB 240905D: AstroSat CZTI detection
  79. GRB 240905D: Fermi GBM Final Real-time Localization
  80. GRB 240905B: AstroSat CZTI detection and localization
  81. GRB 240905C: Fermi GBM Final Real-time Localization
  82. GRB 240905B: Fermi GBM Final Real-time Localization
  83. GRB 240825A: ATCA Detection of Radio Counterpart
  84. Swift GRB 240904A: Global MASTER-Net observations report
  85. GRB 240905A: Fermi GBM Final Real-time Localization
  86. GRB 240904A: Swift detection of a burst
  87. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  89. GRB 240828A: GECAM detection
  90. GRB 240831B: Fermi GBM Final Localization
  91. GRB 240825A: MeerLICHT afterglow detection
  92. GRB 240821A: VLT spectroscopic observations
  93. GRB 240829B: GRBAlpha detection
  94. GRB240828B: REM optical/NIR upper limits
  95. GRB 240828B: AbAO optical upper limit
  96. GRB 240831A: Fermi GBM Final Real-time Localization
  97. GRB 240828B: Mephisto optical upper limit
  98. GRB 240828B: GRANDMA Optical Upper Limit
  99. GRB 240829A: Swift-BAT refined analysis
  100. GRB 240825A: Swift-BAT refined analysis

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