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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"

28097 results found.

  1. LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
  2. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  3. LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
  4. LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
  5. GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
  6. GRB 230510B: Fermi GBM detection
  7. IPN triangulation of GRB 230512A
  8. GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
  9. GRB 230512A: GIT non detection of afterglow candidate
  10. GRB 230512A: Kitab possible afterglow candidate
  11. Fermi trigger No 705565670: Global MASTER-Net observations report
  12. Fermi-LAT gamma-ray observations of IceCube-230511A
  13. GRB 230510A: OHP/T193 and OHP/T120 optical observations
  14. GRB 230512A: Swift-XRT observations
  15. IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
  16. IceCube-Cascade 230511A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 230512A: GIT optical follow-up ZTF candidates
  18. GRB 230512A: Fermi GBM detection
  19. GRB 230512A: Fermi-LAT detection
  20. GRB 230512A: Fermi GBM Final Localization
  21. GRB 230510A: GIT optical upper limits
  22. GRB 230510A: LCOGT Optical Upper Limit
  23. GRB 230510A: Swift/UVOT Observations
  24. GRB 230510B: AstroSat CZTI detection
  25. GRB 230510A: Fermi GBM detection
  26. Fermi trigger No 705446499: Global MASTER-Net observations report
  27. GRB 230510A: Gaoyazi/GOT optical upper limit
  28. GRB 230510A: Nanshan/NEXT optical afterglow detection
  29. GRB 230510B: MAXI/GSC detection
  30. GRB 230506B: Fermi GBM detection
  31. GRB 230510A: Swift-XRT refined Analysis
  32. GRB 230510A: Enhanced Swift-XRT position
  33. GRB 230506C: Fermi GBM detection
  34. GRB 230510A: Swift detection of a burst
  35. GRB 230506C: SAO RAS optical observations
  36. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  37. Fermi-LAT gamma-ray observations of IceCube-230506A
  38. GRB 230506C: Swift-XRT refined Analysis
  39. GRB 230506C: Swift-BAT refined analysis
  40. GRB 230506B: Swift-BAT refined analysis
  41. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  42. GRB 230506B: LCOGT Optical Upper Limits
  43. GRB 230506C: Swift/UVOT Upper Limits
  44. GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
  45. GRB 230506B: Swift-XRT refined Analysis
  46. GRB 230506C: Swift-XRT analysis
  47. GRB 230506C: TSHAO possible afterglow candidate
  48. GRB 230506B: Swift/UVOT Detection
  49. GRB 230506B: Swift detection of a burst
  50. GRB 230506B: Swift detection of a burst
  51. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  52. GRB 230427A: Swift-BAT refined analysis
  53. IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 230420A: AROMA-N Optical Upper Limit
  55. GRB 230427A: NOT optical upper limit
  56. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  57. GRB 230427A: Swift/UVOT Detection
  58. GRB 230427A: Gaoyazi/GOT optical upper limit
  59. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  60. GRB 230427A: Nanshan/HMT optical upper limit
  61. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  62. GRB 230427A: OSIRIS+/GTC observations
  63. GRB 230427A: Swift-XRT refined Analysis
  64. GRB 230426A: VZLUSAT-2 detection
  65. GRB 230427A: GIT optical upper limit
  66. GRB 230427A: Bassano Bresciano Observatory upper limit
  67. GRB 230427A: GMG upper limit
  68. GRB 230427A : OHP/T193 optical upper limit
  69. GRB 230423A(trigger #1165354): Swift-BAT refined analysis
  70. GRB 230427A: AKO Upper Limit
  71. GRB 230427A: MITSuME Akeno optical upper limits
  72. GRB 230426A: Fermi GBM Detection
  73. GRB 230427A: Enhanced Swift-XRT position
  74. GRB 230427A: Swift detection of a burst with an optical counterpart
  75. Fermi trigger No 704233744: Global MASTER-Net observations report
  76. GRB 230423A: Swift/UVOT Upper Limits
  77. GRB 230423A: Swift-XRT refined Analysis
  78. Swift Trigger 1165354 is probably not a GRB
  79. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  80. GRB 230421A: Fermi GBM observation
  81. GRB 230420A: Swift/UVOT Upper Limits
  82. GRB 230421: Swift/BAT-GUANO arcminute localization
  83. GRB230420A: VLT optical observation
  84. GRB 230420A: Swift-BAT refined analysis
  85. GRB 230420A: Swift-XRT refined Analysis
  86. GRB 230420A: MITSuME Akeno optical observation
  87. GRB 230420A: NOT optical afterglow confirmation
  88. GRB 230420A: Gaoyazi/GOT optical upper limit
  89. GRB 230420A: LCOGT Optical Upper Limit
  90. GRB 230420A: Enhanced Swift-XRT position
  91. GRB230414B: VIRT Optical Upper Limit
  92. IPN triangulation of GRB 230418A (short)
  93. GRB 230420A: Swift detection of a burst
  94. GRB 230402A: Fermi GBM detection
  95. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  96. GRB 230418A: Fermi GBM Observation
  97. IceCube-Cascade 230417A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 230402A: Fermi-LAT detection
  99. Fermi-LAT gamma-ray observations of IceCube-230416A
  100. GRB 230414B: Nickel and KAIT telescope optical observations

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