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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"

19589 results found.

  1. GRB 240511A: Prompt enhanced Swift-XRT position
  2. GRB 240511A: Swift detection of a burst
  3. GRB 240504A: Fermi GBM Observation
  4. IPN triangulation of GRB 240504A
  5. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  6. GRB 240415A 1.3m DFOT Optical upper limit
  7. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  8. LVK S240422ed: Further Swift-XRT followup of three sources
  9. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  10. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  11. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  12. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  13. GRB 240419B: Swift-BAT refined analysis
  14. GRB 240421B: Swift-BAT refined analysis
  15. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  16. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  17. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  18. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  19. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  20. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  21. GRB 240421B: GRBAlpha detection
  22. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  23. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  24. GRB 240419A: Swift-BAT refined analysis
  25. GRB 240418A: Swift-BAT refined analysis
  26. LXT240402A/GRB240402B: Chandra X-ray detection
  27. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  28. GRB 240419B : MITSuME Akeno optical upper limits
  29. GRB 240415B: Swift-XRT observations
  30. GRB 240415A: Swift-XRT refined Analysis
  31. GRB 240421B: AstroSat CZTI detection
  32. GRB240421B: Zadko Observations
  33. Swift GRB 240421B: Global MASTER-Net observations report
  34. GRB 240421B: Fermi GBM Observation
  35. GRB 240421B: Swift-XRT refined Analysis
  36. GRB240421B: BOOTES-5/JGT optical upper limit
  37. GRB 240421B: Swift/UVOT Upper Limits
  38. GRB 240421B: Enhanced Swift-XRT position
  39. GRB 240421B: Swift detection of a burst
  40. GRB240419A: Skynet Optical Afterglow Analysis
  41. GRB 240419B: Swift/UVOT Upper Limits
  42. GRB 240419A: Swift/UVOT Upper Limits
  43. GRB 240419B: Swift-XRT refined Analysis
  44. Swift GRB 240419B: Global MASTER-Net observations report
  45. GRB 240419B: Enhanced Swift-XRT position
  46. Swift GRB 240419A: Global MASTER-Net observations report
  47. GRB 240418A: Swift/UVOT Upper Limits
  48. GRB 240419A: Swift-XRT refined Analysis
  49. GRB 240418A: Swift-XRT refined Analysis
  50. GRB 240419B: Swift detection of a burst
  51. GRB 240411B: Swift/UVOT Detection
  52. GRB240418A: YAHPT Upper Limits
  53. GRB 240419A: Enhanced Swift-XRT position
  54. GRB 240419A: Prompt enhanced Swift-XRT position
  55. GRB 240419A: Swift detection of a burst
  56. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  57. GRB 240418A: Enhanced Swift-XRT position
  58. Swift GRB240418.85: Global MASTER-Net observations report
  59. GRB 240418A: Swift detection of a burst
  60. Improved IPN triangulation of GRB 240411A
  61. GRB 240415A: Glowbug gamma-ray detection
  62. GRB 240414A: Glowbug gamma-ray detection
  63. GRB 240415B: GECAM-B detection
  64. GRB 240415A: Swift-BAT refined analysis
  65. GRB 240411A: Glowbug gamma-ray detection
  66. GRB 240414A: Swift-BAT refined analysis
  67. GRB 240414A: AbAO optical upprer limit
  68. GRB 240415A: Swift/UVOT Detection
  69. GRB 240415A: Fermi GBM Observation
  70. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  71. GRB 240415A: Enhanced Swift-XRT position
  72. GRB 240415B: Swift ToO observations
  73. GRB 240415B: Swift/BAT-GUANO Correction
  74. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  75. GRB 240414A: Fermi GBM Observation
  76. GRB 240414A: Swift/UVOT Detection
  77. LXT 240402A/GRB 240402B: Swift follow-up observations
  78. GRB 240414A: Mondy optical observations
  79. GRB 240415A: Prompt Swift-XRT observations
  80. GRB 240415A: Swift detection of a burst
  81. GRB 240414A: Swift-XRT refined Analysis
  82. GRB 240414A: Enhanced Swift-XRT position
  83. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  84. GRB 240414A: Skynet Optical Afterglow Observations
  85. Swift GRB 240414A: Global MASTER-Net observations report
  86. IPN triangulation of GRB 240410A
  87. IPN triangulation of GRB 240411A
  88. GRB 240414A : MITSuME Akeno optical upper limits
  89. GRB 240414A: Swift detection of a burst
  90. GRB 240411B: Swift-BAT refined analysis
  91. GRB 240411B: Swift-XRT refined Analysis
  92. GRB 240411B: 1.3m DFOT Optical observations
  93. GRB 240411B: Enhanced Swift-XRT position
  94. GRB 240411B: Swift detection of a burst
  95. EP240408A: MASTER optical observations
  96. EP240408a: GROND detection of a candidate counterpart
  97. EP240408a: Swift follow-up observation
  98. Swift Trigger 1220736: detection of 4U 1543-62.
  99. Swift satellite resumes pointed science observations
  100. GRB 240318A: Fermi GBM Observation

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