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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"

27776 results found.

  1. GRB 240425A: Fermi GBM Final Real-time Localization
  2. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  3. GRB 240419B: Swift-BAT refined analysis
  4. GRB 240421B: Swift-BAT refined analysis
  5. GRB 240422A: Glowbug gamma-ray detection
  6. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  7. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  8. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  9. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  10. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  11. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  12. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  13. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  14. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  15. GRB 240421B: GRBAlpha detection
  16. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  17. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  18. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  19. GRB 240419A: Swift-BAT refined analysis
  20. GRB 240418A: Swift-BAT refined analysis
  21. LXT240402A/GRB240402B: Chandra X-ray detection
  22. GRB 240419A: Possible ATCA radio detection
  23. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  24. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  25. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  26. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  27. GRB 240421A: Glowbug gamma-ray detection
  28. GRB 240414A: radio detection with the VLA
  29. GRB 240414A: LBT optical detection
  30. GRB 240419B : MITSuME Akeno optical upper limits
  31. GRB 240415B: Swift-XRT observations
  32. GRB 240415A: Swift-XRT refined Analysis
  33. GRB 240421B: AstroSat CZTI detection
  34. GRB 240422A: Fermi GBM Final Real-time Localization
  35. GRB240421B: Zadko Observations
  36. Swift GRB 240421B: Global MASTER-Net observations report
  37. GRB 240421B: Fermi GBM Observation
  38. GRB 240421B: Swift-XRT refined Analysis
  39. GRB240421B: BOOTES-5/JGT optical upper limit
  40. GRB 240421B: Swift/UVOT Upper Limits
  41. GRB 240421B: Enhanced Swift-XRT position
  42. EP240417a: no counterpart detection by SOAR
  43. EP240420a: TNT upper limit to its optical counterpart
  44. GRB 240421B: Swift detection of a burst
  45. GRB 240421A: Fermi GBM Final Real-time Localization
  46. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  47. GRB240419A: Skynet Optical Afterglow Analysis
  48. GRB 240419B: Swift/UVOT Upper Limits
  49. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  50. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  51. EP240420a: EP-WXT detection of a fast X-ray transient
  52. GRB 240419A: Swift/UVOT Upper Limits
  53. GRB 240419B: Swift-XRT refined Analysis
  54. Swift GRB 240419B: Global MASTER-Net observations report
  55. GRB 240419B: Enhanced Swift-XRT position
  56. Swift GRB 240419A: Global MASTER-Net observations report
  57. GRB 240418A: Swift/UVOT Upper Limits
  58. GRB 240419A: REM NIR afterglow detection
  59. GRB 240419A: Swift-XRT refined Analysis
  60. GRB 240418A: Swift-XRT refined Analysis
  61. GRB 240419B: Swift detection of a burst
  62. GRB 240411B: Swift/UVOT Detection
  63. EP240417a: YAHPT Optical Upper Limits
  64. GRB240418A: YAHPT Upper Limits
  65. GRB 240419A: VLT/UVES redshift of z = 5.178
  66. GRB 240419A: VLT optical afterglow detection
  67. GRB 240419A: Enhanced Swift-XRT position
  68. GRB 240419A: Prompt enhanced Swift-XRT position
  69. GRB 240419A: Swift detection of a burst
  70. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  71. GRB 240418A: Enhanced Swift-XRT position
  72. Swift GRB240418.85: Global MASTER-Net observations report
  73. GRB 240418A: Swift detection of a burst
  74. EP240417a: EP-WXT detection of a fast X-ray transient
  75. Improved IPN triangulation of GRB 240411A
  76. GRB 240417A: Fermi GBM Final Real-time Localization
  77. GRB 240415A: Glowbug gamma-ray detection
  78. GRB 240414A: Glowbug gamma-ray detection
  79. GRB 240415B: GECAM-B detection
  80. GRB 240415A: Swift-BAT refined analysis
  81. GRB 240411A: Glowbug gamma-ray detection
  82. GRB 240414A: Swift-BAT refined analysis
  83. EP240416a: EP-WXT detection of a fast X-ray transient
  84. GRB 240414A: AbAO optical upprer limit
  85. GRB 240415A: Swift/UVOT Detection
  86. GRB 240415A: Fermi GBM Observation
  87. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  88. EP240414a: EP-FXT follow-up observation
  89. GRB 240415A: Enhanced Swift-XRT position
  90. GRB 240415B: Swift ToO observations
  91. GRB 240415B: Swift/BAT-GUANO Correction
  92. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  93. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  94. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  95. GRB 240414A: Fermi GBM Observation
  96. GRB 240415A: Mondy optical transient detection
  97. GRB 240414A: Swift/UVOT Detection
  98. LXT 240402A/GRB 240402B: Swift follow-up observations
  99. GRB 240414A: Mondy optical observations
  100. GRB 240414B: Fermi GBM Final Real-time Localization

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