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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"

27779 results found.

  1. IPN triangulation of GRB 240913C / EP 240913a
  2. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  3. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  4. GRB 240916A: Fermi GBM Observation
  5. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  6. GRB 240916A: Swift-XRT afterglow detection
  7. GRB 240916A: Swift ToO observations
  8. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  9. GRB 240916B: Fermi GBM Final Real-time Localization
  10. GRB 240914B: Fermi GBM Final Localization
  11. GRB 240916A: Fermi GBM Final Real-time Localization
  12. EP240913a/GRB 240913C: KAIT optical upper limit
  13. GRB 240913C: Fermi GBM detection
  14. GRB 240914A: Swift-XRT observations
  15. GRB 240914B: AstroSat CZTI detection
  16. EP240913A / GRB 240913C: AstroSat CZTI detection
  17. GRB 240914A: Swift ToO observations
  18. EP240913a: ESO-NTT optical observations
  19. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  20. GRB 240905E: further NOT optical observations
  21. EP240913a: EP-WXT detection of a fast X-ray transient
  22. GRB 240913B: Fermi GBM Final Real-time Localization
  23. GRB 240911A: LCO optical observations
  24. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  25. GRB 240912A: Swift/UVOT Detection
  26. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  27. GRB 240912A: SVOM/GRM observation
  28. GRB 240911A: Swift-XRT observations
  29. GRB 240913A: Fermi GBM Final Real-time Localization
  30. GRB 240912A: J-band observations with WINTER
  31. GRB 240912A: Swift-XRT refined Analysis
  32. GRB 240912A: Fermi GBM Observation
  33. Swift GRB 240912A: Global MASTER-Net observations report
  34. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  35. GRB 240911A: Tiled Swift observations
  36. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  37. GRB 240912B: Fermi GBM Final Real-time Localization
  38. GRB 240912A: NOT optical spectroscopy
  39. GRB 240912A: Enhanced Swift-XRT position
  40. GRB 240912A: Swift detection of a burst with an optical counterpart
  41. GRB 240912A: Fermi GBM Final Real-time Localization
  42. GRB 240910A: Fermi GBM Observation
  43. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  44. GRB 240910A: JinShan optical observations
  45. GRB 240910A: GOTO candidate optical counterpart
  46. EP240908a: Optical afterglow confirmation
  47. GRB 240910A: Swift ToO observations
  48. IPN triangulation of GRB 240905B (short)
  49. GRB 240825A: 7DT Optical Upper Limit
  50. GRB 240905E: SVOM/VT optical observations
  51. GRB 240910A: GRBAlpha detection
  52. GRB 240910B: Fermi GBM Final Real-time Localization
  53. EP240908a: Updates on the WXT detection result around the trigger time
  54. GRB 240910A: Fermi GBM Final Real-time Localization
  55. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  56. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  57. EP240908a: optical afterglow candidate
  58. GRB 240905B: GOTO optical upper limits
  59. EP240908a: EP detection of a fast X-ray transient
  60. GRB 240908A: Fermi GBM Final Real-time Localization
  61. GRB 240905E: GIT optical upper limit
  62. GRB 240905B: Swift-XRT observations
  63. GRB 240905E: Gaoyazi/GOT optical upper limits
  64. GRB 240905B: Fermi-LAT detection
  65. GRB 240905B: Swift ToO observations
  66. GRB 240905E: J-band observations with WINTER
  67. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  68. GRB 240905E: AKO Optical Upper Limit
  69. GRB 240905E: SVOM/C-GFT optical upper limit
  70. GRB 240905E: NOT optical upper limits
  71. GRB 240905E: REM optical/NIR upper limits
  72. GRB 240902B: AstroSat CZTI detection of a long burst
  73. GRB 240905E: Swift-XRT refined Analysis
  74. GRB 240902A: AstroSat CZTI detection of a long burst
  75. GRB 240905E: SVOM/GRM observation
  76. GRB 240905E: LCOGT Optical Upper Limit
  77. GRB 240905E: Swift/UVOT Upper Limits
  78. GRB 240905E: SAO RAS optical upper limit
  79. GRB 240905E: Nanshan/HMT optical upper limit
  80. Swift GRB 240905E: Global MASTER-Net observations report
  81. GRB 240905E: Swift detection of a burst
  82. GRB 240819A: Optical upper limits from TESS
  83. GRB 240905D: AstroSat CZTI detection
  84. GRB 240905D: Fermi GBM Final Real-time Localization
  85. GRB 240905B: AstroSat CZTI detection and localization
  86. GRB 240905C: Fermi GBM Final Real-time Localization
  87. GRB 240905B: Fermi GBM Final Real-time Localization
  88. GRB 240825A: ATCA Detection of Radio Counterpart
  89. Swift GRB 240904A: Global MASTER-Net observations report
  90. GRB 240905A: Fermi GBM Final Real-time Localization
  91. GRB 240904A: Swift detection of a burst
  92. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  94. GRB 240828A: GECAM detection
  95. GRB 240831B: Fermi GBM Final Localization
  96. GRB 240825A: MeerLICHT afterglow detection
  97. GRB 240821A: VLT spectroscopic observations
  98. GRB 240829B: GRBAlpha detection
  99. GRB240828B: REM optical/NIR upper limits
  100. GRB 240828B: AbAO optical upper limit

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