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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"

18478 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  2. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  3. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  4. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  5. GRB 240419B: Swift-BAT refined analysis
  6. GRB 240421B: Swift-BAT refined analysis
  7. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  8. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  9. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  10. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  11. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  12. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  13. GRB 240421B: GRBAlpha detection
  14. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  15. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  16. GRB 240419A: Swift-BAT refined analysis
  17. GRB 240418A: Swift-BAT refined analysis
  18. LXT240402A/GRB240402B: Chandra X-ray detection
  19. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  20. GRB 240419B : MITSuME Akeno optical upper limits
  21. GRB 240415B: Swift-XRT observations
  22. GRB 240415A: Swift-XRT refined Analysis
  23. GRB 240421B: AstroSat CZTI detection
  24. GRB240421B: Zadko Observations
  25. Swift GRB 240421B: Global MASTER-Net observations report
  26. GRB 240421B: Fermi GBM Observation
  27. GRB 240421B: Swift-XRT refined Analysis
  28. GRB240421B: BOOTES-5/JGT optical upper limit
  29. GRB 240421B: Swift/UVOT Upper Limits
  30. GRB 240421B: Enhanced Swift-XRT position
  31. GRB 240421B: Swift detection of a burst
  32. GRB240419A: Skynet Optical Afterglow Analysis
  33. GRB 240419B: Swift/UVOT Upper Limits
  34. GRB 240419A: Swift/UVOT Upper Limits
  35. GRB 240419B: Swift-XRT refined Analysis
  36. Swift GRB 240419B: Global MASTER-Net observations report
  37. GRB 240419B: Enhanced Swift-XRT position
  38. Swift GRB 240419A: Global MASTER-Net observations report
  39. GRB 240418A: Swift/UVOT Upper Limits
  40. GRB 240419A: Swift-XRT refined Analysis
  41. GRB 240418A: Swift-XRT refined Analysis
  42. GRB 240419B: Swift detection of a burst
  43. GRB 240411B: Swift/UVOT Detection
  44. GRB240418A: YAHPT Upper Limits
  45. GRB 240419A: Enhanced Swift-XRT position
  46. GRB 240419A: Prompt enhanced Swift-XRT position
  47. GRB 240419A: Swift detection of a burst
  48. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  49. GRB 240418A: Enhanced Swift-XRT position
  50. Swift GRB240418.85: Global MASTER-Net observations report
  51. GRB 240418A: Swift detection of a burst
  52. Improved IPN triangulation of GRB 240411A
  53. GRB 240415A: Glowbug gamma-ray detection
  54. GRB 240414A: Glowbug gamma-ray detection
  55. GRB 240415B: GECAM-B detection
  56. GRB 240415A: Swift-BAT refined analysis
  57. GRB 240411A: Glowbug gamma-ray detection
  58. GRB 240414A: Swift-BAT refined analysis
  59. GRB 240414A: AbAO optical upprer limit
  60. GRB 240415A: Swift/UVOT Detection
  61. GRB 240415A: Fermi GBM Observation
  62. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  63. GRB 240415A: Enhanced Swift-XRT position
  64. GRB 240415B: Swift ToO observations
  65. GRB 240415B: Swift/BAT-GUANO Correction
  66. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  67. GRB 240414A: Fermi GBM Observation
  68. GRB 240414A: Swift/UVOT Detection
  69. LXT 240402A/GRB 240402B: Swift follow-up observations
  70. GRB 240414A: Mondy optical observations
  71. GRB 240415A: Prompt Swift-XRT observations
  72. GRB 240415A: Swift detection of a burst
  73. GRB 240414A: Swift-XRT refined Analysis
  74. GRB 240414A: Enhanced Swift-XRT position
  75. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  76. GRB 240414A: Skynet Optical Afterglow Observations
  77. Swift GRB 240414A: Global MASTER-Net observations report
  78. IPN triangulation of GRB 240410A
  79. IPN triangulation of GRB 240411A
  80. GRB 240414A : MITSuME Akeno optical upper limits
  81. GRB 240414A: Swift detection of a burst
  82. GRB 240411B: Swift-BAT refined analysis
  83. GRB 240411B: Swift-XRT refined Analysis
  84. GRB 240411B: 1.3m DFOT Optical observations
  85. GRB 240411B: Enhanced Swift-XRT position
  86. GRB 240411B: Swift detection of a burst
  87. EP240408A: MASTER optical observations
  88. EP240408a: GROND detection of a candidate counterpart
  89. EP240408a: Swift follow-up observation
  90. Swift Trigger 1220736: detection of 4U 1543-62.
  91. Swift satellite resumes pointed science observations
  92. GRB 240318A: Fermi GBM Observation
  93. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  94. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  95. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  96. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  97. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  98. GRB 240317B: Fermi GBM Observation
  99. Swift satellite in safe mode
  100. GRB 240317B: Swift/BAT-GUANO arcminute localization of a burst

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