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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

16218 results found.

  1. EP241021a: EP detection of a fast X-ray transient
  2. GRB 241018A/sb24101802: Mephisto optical upper limit
  3. GRB 241017A/sb24101702: Mephisto optical upper limit
  4. GRB 241018A: Mondy optical upper limit
  5. GRB 241018A: GROWTH-India telescope optical upper limit
  6. GRB241018A: XingLong Optical Upper Limit
  7. GRB 241018A: Swift-XRT observations
  8. GRB 241018A: REM optical/NIR upper limits
  9. GRB 241018A: NOT optical observations
  10. GRB 241018A: SVOM/VT follow-up and optical candidate
  11. GRB 241018A: LCO/0.4m optical upper limits
  12. GRB 241006A: VIRT Optical Upper Limit
  13. GRB 240727A: VIRT Optical Upper Limit
  14. GRB 241018A: X-ray afterglow candidate observed by MXT
  15. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  16. GRB 241001A: EP-FXT afterglow detection
  17. GRB 241017A: GROWTH-India Telescope optical upper limit
  18. GRB241017A: TOO Observations by SVOM/MXT
  19. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  20. GRB 241017A: J-band upper limit from WINTER
  21. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  22. GRB 241013A: Fermi GBM Observation
  23. GRB 240916A: radio detection with the VLA
  24. GRB241013A: REM observations
  25. GRB 241009A: LCO optical upper limits
  26. GRB 241009A: GRANDMA optical upper limits
  27. GRB 241009A: Swift-XRT afterglow detection
  28. GRB 241010A: JinShan optical observations and potential host galaxy
  29. GRB 241006A: ATCA Radio Upper Limits
  30. GRB 241010A: Swift-XRT refined Analysis
  31. GRB 241010A: J-band observations with WINTER
  32. GRB 241010A: Enhanced Swift-XRT position
  33. GRB 241010A: LCO optical observations
  34. GRB 241010A: Swift detection of a burst with an optical counterpart
  35. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  36. GRB 241002B: Swift-XRT afterglow detection
  37. GRB 241002A: NOT optical upper limits
  38. IceCube-241006A: No candidates from the Zwicky Transient Facility
  39. GRB 241006A: GRANDMA optical upper limits
  40. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  41. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  42. GRB 240910A: LBT optical observations
  43. GRB 241006A: PRIME near-infrared upper limits
  44. GRB 241006A: Swift/UVOT Upper Limits
  45. GRB 241001A: Swift-XRT afterglow detection
  46. GRB 241006A: Enhanced Swift-XRT position
  47. GRB 241006A: Swift detection of a burst
  48. GRB 240930B: SVOM/C-GFT optical upper limit
  49. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  50. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  51. GRB 241002C: SVOM/C-GFT optical upper limit
  52. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  53. GRB 241002B: PRIME near-infrared detection
  54. IPN triangulation of GRB 240930B / EP 240930a
  55. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  56. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  57. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  58. GRB 241002C : MITSuME Akeno optical upper limits
  59. GRB241001A: REM optical/NIR upper limits
  60. GRB 241002A: Swift/UVOT Upper Limits
  61. EP240930a: Liverpool Telescope observations
  62. GRB 241002A: Swift-XRT refined Analysis
  63. GRB 241002A: LCOGT Optical Upper Limits
  64. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  65. GRB 241001A: Swift/UVOT Detection
  66. GRB 240929A: Liverpool Telescope prompt followup observations
  67. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  68. GRB241001A: optical afterglow candidate
  69. GRB 241002A: Enhanced Swift-XRT position
  70. GRB 241002A: Swift detection of a burst
  71. GRB 240930B: Fermi GBM Observation
  72. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  73. EP240930a: EP-FXT follow-up observation update
  74. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  75. EP240930a: EP-WXT detection of a fast X-ray transient
  76. GRB 240929A : Leavitt Observatory optical upper limit
  77. GRB 240825A: LBT optical observations
  78. Swift Trigger 1256950 is probably not a GRB
  79. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  80. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  81. EP240919a / GRB 240919A: SVOM/VT upper limit
  82. EP240918b and EP240918c: EP-FXT follow-up observations
  83. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  84. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  85. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  86. EP240919a: EP-FXT follow-up observation update
  87. EP240913A/GRB 240913C: AbAO optical upper limit
  88. EP240919a / GRB 240919A: Mondy optical upper limit
  89. EP240913a/GRB 240913C: 1.6m Mephisto observations
  90. EP240918a: SVOM/VT upper limit
  91. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  92. EP240919a / GRB 240919A: REM optical and NIR upper limits
  93. EP240918b and EP240918c: Optical upper limits with Kinder observations
  94. GRB 240414A: further radio observations with the VLA
  95. EP240919a: Optical upper limit with Kinder observations
  96. GRB 240910A: radio detection with the VLA
  97. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  98. EP240919a: NOT and Gemini optical observations
  99. EP240919a: GOTO optical upper limits
  100. EP240919a: JinShan optical upper limits

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