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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"

32132 results found.

  1. GRB 240501B: GRBAlpha detection
  2. GRB 240430A: GRBAlpha detection
  3. GRB 240502B: Fermi GBM Final Real-time Localization
  4. GRB 240502A long GRB detected by INTEGRAL
  5. GRB 240502A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 240501A: Global MASTER-Net observations report
  7. GRB 240426A: VZLUSAT-2 detection
  8. GRB 240425A: VZLUSAT-2 detection
  9. GRB240430A: Fermi GBM Final Localization
  10. GRB 240501B: AstroSat CZTI detection
  11. GRB 240501A: Fermi GBM Final Real-time Localization
  12. GRB 240408B: VZLUSAT-2 detection
  13. GRB 240407A: VZLUSAT-2 detection
  14. X-ray transient EP240414a: Detection of associated supernova
  15. GRB 240425A: GRBAlpha detection
  16. GRB 240429A: Fermi GBM Final Real-time Localization
  17. Fermi GRB 240428A: Global MASTER-Net observations report
  18. GRB 240428A: Fermi GBM Final Real-time Localization
  19. GRB 240426A: AstroSat CZTI detection
  20. GRB 240414A: NOEMA detection
  21. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  22. GRB 240425A: Fermi GBM Final Real-time Localization
  23. GRB 240419B: Swift-BAT refined analysis
  24. GRB 240421B: Swift-BAT refined analysis
  25. GRB 240422A: Glowbug gamma-ray detection
  26. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 240421B: GRBAlpha detection
  28. GRB 240419A: Swift-BAT refined analysis
  29. GRB 240418A: Swift-BAT refined analysis
  30. LXT240402A/GRB240402B: Chandra X-ray detection
  31. GRB 240419A: Possible ATCA radio detection
  32. GRB 240421B: ATCA radio observations
  33. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  34. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  35. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  36. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  37. GRB 240421A: Glowbug gamma-ray detection
  38. GRB 240414A: radio detection with the VLA
  39. GRB 240414A: AMI-LA radio observations
  40. GRB 240414A: LBT optical detection
  41. GRB 240419B : MITSuME Akeno optical upper limits
  42. GRB 240415B: Swift-XRT observations
  43. GRB 240415A: Swift-XRT refined Analysis
  44. Fermi GRB 240422A: Global MASTER-Net observations report
  45. GRB 240421B: AstroSat CZTI detection
  46. GRB 240422A: Fermi GBM Final Real-time Localization
  47. GRB240421B: Zadko Observations
  48. Fermi GRB 240421B: Global MASTER-Net observations report
  49. Swift GRB 240421B: Global MASTER-Net observations report
  50. GRB 240421B: Fermi GBM Observation
  51. GRB 240421B: Swift-XRT refined Analysis
  52. GRB240421B: BOOTES-5/JGT optical upper limit
  53. GRB 240421B: J-band upper limits from WINTER
  54. GRB 240421B: Swift/UVOT Upper Limits
  55. GRB 240421B: Enhanced Swift-XRT position
  56. Fermi GRB 240421A: Global MASTER-Net observations report
  57. GRB 240421B: Swift detection of a burst
  58. EP240420a: Nanshan optical counterpart observations
  59. GRB 240421A: Fermi GBM Final Real-time Localization
  60. GRB240419A: Skynet Optical Afterglow Analysis
  61. GRB240418A - Candidate afterglow from NIRES
  62. GRB 240419B: Swift/UVOT Upper Limits
  63. GRB 240419A: Swift/UVOT Upper Limits
  64. GRB 240419B: Swift-XRT refined Analysis
  65. GRB 240419B: optical afterglow from the NOT
  66. Swift GRB 240419B: Global MASTER-Net observations report
  67. EP240414A: Terskol Zeiss-2000 optical upper limit
  68. GRB 240419B: Enhanced Swift-XRT position
  69. Swift GRB 240419A: Global MASTER-Net observations report
  70. GRB 240418A: Swift/UVOT Upper Limits
  71. GRB 240419A: REM NIR afterglow detection
  72. GRB 240419A: Swift-XRT refined Analysis
  73. GRB 240418A: Swift-XRT refined Analysis
  74. GRB 240419B: Swift detection of a burst
  75. GRB 240411B: Swift/UVOT Detection
  76. GRB240418A: YAHPT Upper Limits
  77. GRB 240419A: VLT/UVES redshift of z = 5.178
  78. GRB 240419A: VLT optical afterglow detection
  79. GRB 240419A: Enhanced Swift-XRT position
  80. GRB 240419A: Prompt enhanced Swift-XRT position
  81. GRB 240419A: Swift detection of a burst
  82. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  83. GRB 240418A: NOT optical upper limits
  84. GRB 240418A: Enhanced Swift-XRT position
  85. GRB 240418A: AKO Upper Limit
  86. GRB 240411A: GOTO early optical upper limits
  87. GRB 240418A: Swift detection of a burst
  88. Fermi GRB 240417A: Global MASTER-Net observations report
  89. EP240416A: Terskol Zeiss-2000 optical upper limit
  90. EP240416A: Khureltogoot optical upper limit
  91. Improved IPN triangulation of GRB 240411A
  92. GRB 240417A: Fermi GBM Final Real-time Localization
  93. GRB 240415A: Glowbug gamma-ray detection
  94. GRB 240414A: Glowbug gamma-ray detection
  95. GRB 240415B: GECAM-B detection
  96. EP 240416a: Xinglong and NOT decaying optical counterpart
  97. GRB 240415A: Swift-BAT refined analysis
  98. GRB 240411A: Glowbug gamma-ray detection
  99. GRB 240414A: Swift-BAT refined analysis
  100. GRB 240414A: AbAO optical upprer limit

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