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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"

21455 results found.

  1. GRB 240511A: Swift detection of a burst
  2. GRB 240504A: Fermi GBM Observation
  3. IPN triangulation of GRB 240504A
  4. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  5. GRB 240415A 1.3m DFOT Optical upper limit
  6. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  7. LVK S240422ed: Further Swift-XRT followup of three sources
  8. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  9. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  10. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  11. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  12. GRB 240419B: Swift-BAT refined analysis
  13. GRB 240421B: Swift-BAT refined analysis
  14. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  15. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  16. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  17. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  18. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  19. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  20. GRB 240421B: GRBAlpha detection
  21. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  22. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  23. GRB 240419A: Swift-BAT refined analysis
  24. GRB 240418A: Swift-BAT refined analysis
  25. LXT240402A/GRB240402B: Chandra X-ray detection
  26. GRB 240419A: Possible ATCA radio detection
  27. GRB 240421B: ATCA radio observations
  28. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  29. GRB 240419B : MITSuME Akeno optical upper limits
  30. GRB 240415B: Swift-XRT observations
  31. GRB 240415A: Swift-XRT refined Analysis
  32. GRB 240421B: AstroSat CZTI detection
  33. GRB240421B: Zadko Observations
  34. Swift GRB 240421B: Global MASTER-Net observations report
  35. GRB 240421B: Fermi GBM Observation
  36. GRB 240421B: Swift-XRT refined Analysis
  37. GRB240421B: BOOTES-5/JGT optical upper limit
  38. GRB 240421B: Swift/UVOT Upper Limits
  39. GRB 240421B: Enhanced Swift-XRT position
  40. GRB 240421B: Swift detection of a burst
  41. GRB240419A: Skynet Optical Afterglow Analysis
  42. GRB 240419B: Swift/UVOT Upper Limits
  43. GRB 240419A: Swift/UVOT Upper Limits
  44. GRB 240419B: Swift-XRT refined Analysis
  45. Swift GRB 240419B: Global MASTER-Net observations report
  46. GRB 240419B: Enhanced Swift-XRT position
  47. Swift GRB 240419A: Global MASTER-Net observations report
  48. GRB 240418A: Swift/UVOT Upper Limits
  49. GRB 240419A: Swift-XRT refined Analysis
  50. GRB 240418A: Swift-XRT refined Analysis
  51. GRB 240419B: Swift detection of a burst
  52. GRB 240411B: Swift/UVOT Detection
  53. GRB240418A: YAHPT Upper Limits
  54. GRB 240419A: VLT optical afterglow detection
  55. GRB 240419A: Enhanced Swift-XRT position
  56. GRB 240419A: Prompt enhanced Swift-XRT position
  57. GRB 240419A: Swift detection of a burst
  58. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  59. GRB 240418A: Enhanced Swift-XRT position
  60. GRB 240418A: AKO Upper Limit
  61. Swift GRB240418.85: Global MASTER-Net observations report
  62. GRB 240418A: Swift detection of a burst
  63. Improved IPN triangulation of GRB 240411A
  64. GRB 240415A: Glowbug gamma-ray detection
  65. GRB 240414A: Glowbug gamma-ray detection
  66. GRB 240415B: GECAM-B detection
  67. GRB 240415A: Swift-BAT refined analysis
  68. GRB 240411A: Glowbug gamma-ray detection
  69. GRB 240414A: Swift-BAT refined analysis
  70. GRB 240414A: AbAO optical upprer limit
  71. GRB 240415A: Swift/UVOT Detection
  72. GRB 240415A: Fermi GBM Observation
  73. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  74. GRB 240415A: Enhanced Swift-XRT position
  75. GRB 240415B: Swift ToO observations
  76. GRB 240415B: Swift/BAT-GUANO Correction
  77. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  78. GRB 240414A: Fermi GBM Observation
  79. GRB 240414A: Swift/UVOT Detection
  80. LXT 240402A/GRB 240402B: Swift follow-up observations
  81. GRB 240414A: Mondy optical observations
  82. GRB 240415A: Prompt Swift-XRT observations
  83. GRB 240415A: Swift detection of a burst
  84. GRB 240414A: Swift-XRT refined Analysis
  85. GRB 240414A: Enhanced Swift-XRT position
  86. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  87. GRB 240414A: Skynet Optical Afterglow Observations
  88. Swift GRB 240414A: Global MASTER-Net observations report
  89. IPN triangulation of GRB 240410A
  90. IPN triangulation of GRB 240411A
  91. GRB 240414A : MITSuME Akeno optical upper limits
  92. GRB 240414A : OHP/T193 optical counterpart detection
  93. GRB 240414A: Swift detection of a burst
  94. GRB 240411B: Swift-BAT refined analysis
  95. GRB 240411B: Swift-XRT refined Analysis
  96. GRB 240411B: 1.3m DFOT Optical observations
  97. GRB 240411B: Enhanced Swift-XRT position
  98. GRB 240411B: LCO optical afterglow detection
  99. GRB 240411B: Swift detection of a burst
  100. EP240408A: MASTER optical observations

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