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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"

28045 results found.

  1. LIGO/Virgo S190425z: VISTA K-band observations of the Swift/UVOT Transient
  2. GRB 190427A: Swift/UVOT Upper Limits
  3. Fermi Trigger 578170097 / GRB 190428783 / GRB190428A: BALROG localization
  4. LIGO/Virgo S190426c: Additional Candidates from the Zwicky Transient Facility
  5. GRB 190427A, Swift-BAT refined analysis
  6. LIGO/Virgo S190426c: Continued infrared wide-field search with Palomar Gattini-IR
  7. LIGO/Virgo S190425z: 1.5m OSN and 10.4m imaging of the UVOT source field
  8. LIGO/Virgo S190425z: NOT photometry of ZTF19aasckkq
  9. LIGO/Virgo S190426c: GROWTH India follow-up
  10. LIGO/Virgo S190425z: No Optical Detection of the Swift/UVOT Transient in ASAS-SN observations hours before and after discovery
  11. LIGO/Virgo S190425z: Potential host galaxy of UVOT candidate counterpart found in BLISS
  12. LIGO/Virgo S190426c: DDOTI/OAN Optical Observations
  13. LIGO/Virgo S190425z: ASAS-SN observations
  14. LIGO/Virgo S190425z: No Optical Detection of the Swift/UVOT Transient with Las Cumbres Observatory
  15. LIGO/Virgo S190425z: Swift/UVOT and XRT pre-images at the position of the potential Swift/UVOT counterpart
  16. LIGO/Virgo S190426c: J-GEM optical/NIR follow-up observations
  17. LIGO/Virgo S190425z: Transient found in Swift/UVOT counterpart search
  18. LIGO/Virgo S190426c: MMT Follow-Up Observations
  19. LIGO/Virgo S190426c: GOTO optical coverage - no notable counterparts
  20. GRB 190427A: Lick/Nickel telescope optical observations
  21. LIGO/Virgo S190426c: Lick/KAIT Follow-Up Observations
  22. GRB 190427A: COATLI Optical Observations
  23. LIGO/Virgo S190426c: CNEOST Optical Observations
  24. LIGO/Virgo S190425z: CNEOST Optical Observations
  25. LIGO/Virgo S190426c: Infrared Wide-field Search with Palomar Gattini-IR
  26. LIGO/Virgo S190426c: Optical Wide-field Search with the Zwicky Transient Facility
  27. GRB 190427A: RATIR Optical and NIR Observations
  28. LIGO/Virgo S190426c: Nanshan/NEXT Observation of Galaxies
  29. LIGO/Virgo S190426c: Insight-HXMT/HE observation
  30. LIGO/Virgo S190426c: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  31. LIGO/Virgo S190426c: Updated localization from LIGO and Virgo data
  32. LIGO/Virgo S190426c: Swift-XRT sources
  33. GRB 190427A: BOOTES-1 and BOOTES-5/JGT early follow-up observations
  34. ANTARES follow-up of the GW candidate S190426c
  35. LIGO/Virgo S190425z: Fermi-LAT search for a high-energy gamma-ray counterpart
  36. GRB 190427A: NOT optical observations
  37. GRB 190427A: Swift-XRT observations
  38. LIGO/Virgo S190425z: Additional Pan-STARRS transients in the skymap
  39. LIGO/Virgo S190426c: MAXI/GSC Observations
  40. LIGO/Virgo S190426c: GROWTH India follow-up
  41. LIGO/Virgo S190425z: GRANDMA follow-up observations with Les Makes-T60, AZT-8 and Abastumani-T70
  42. LIGO/Virgo S190426c: Swift/BAT Counterpart Search
  43. LIGO/Virgo S190426c: a possible lensed NS-NS merger
  44. LIGO/Virgo S190426c: Fermi GBM Observations
  45. LIGO/Virgo S190426c: AGILE-GRID Observations
  46. LIGO-Virgo S190426c: AGILE MCAL observation
  47. LIGO/Virgo S190425z: Further MMT Follow-Up Observations
  48. LIGO/Virgo S190426c: Potential host galaxies from the GLADE catalog
  49. LIGO/Virgo S190426c: INTEGRAL prompt observation
  50. Baksan Neutrino Observatory Alert 190405.62: Global MASTER-Net:LIGO/Virgo S190425z: PanSTARR OT AT2019ebq/PS19qp
  51. LIGO/Virgo S190425z: Pierre Auger Observatory follow-up
  52. LIGO/Virgo S190426c: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo S190426c: HAWC follow-up
  54. LIGO/Virgo S190425z: GROND observations of AT2019ebq/PS19qp
  55. LIGO/Virgo S190425z: Updated localization from LIGO and Virgo data
  56. LIGO/Virgo S190425z: GOTO observations
  57. LIGO/Virgo S190425z: ZTF pre-merger limits on PS1 candidates
  58. LIGO/Virgo S190425z : IRSF/SIRIUS NIR photometry of ZTF19aarykkb and ZTF19aarzaod
  59. LIGO/Virgo S190425z: Insight-HXMT/HE observation
  60. LIGO/Virgo S190425z: Swope follow-up observations
  61. LIGO/Virgo S190425z - ePESSTO+ NTT observations
  62. LIGO/Virgo S190425z: Pan-STARRS observations and transients in the skymap
  63. LIGO/Virgo S190425z - GROWTH-India follow-up of two ZTF candidates
  64. LIGO/Virgo S190425z: OVRO-LWA simultaneous low frequency radio observations of localization region
  65. LIGO/Virgo S190425z: J-GEM optical follow-up observations with Subaru/FOCAS
  66. LIGO/Virgo S190425z: Xinglong/Schmidt follow-up observations
  67. LIGO/Virgo S190425z: Palomar Gattini-IR wide-field infrared follow-up
  68. LIGO/Virgo S190425z: AGILE-GRID Observations
  69. LIGO/Virgo S190425z: Fermi GBM Observations
  70. LIGO/Virgo S190425z: Swift/BAT Counterpart Search
  71. LIGO/Virgo S190425z: INTEGRAL IBIS prompt observation
  72. LIGO-Virgo S190425z: AGILE MCAL observation
  73. LIGO/Virgo S190425z: Lick/KAIT Follow-Up Observations
  74. LIGO/Virgo S190425z: MAXI/GSC Observations
  75. LIGO/Virgo S190425z: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  76. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  77. LIGO/VirgoS190425z: HAWC follow-up
  78. LIGO/Virgo S190425z: SAGUARO follow-up observations
  79. LIGO/Virgo S190425z: Potential host galaxies from the GLADE catalog
  80. LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
  81. LIGO/Virgo S190425z: Identification of a GW compact binary merger candidate
  82. GRB 190424A: Swift-BAT refined analysis
  83. GRB 190422A: Fermi GBM detection
  84. LIGO/Virgo S190421ar: Lick/KAIT Follow-Up Observations
  85. GRB 190422A: Swift/UVOT Upper Limits
  86. LIGO/Virgo S190421ar: Swift/BAT Counterpart Search
  87. GRB 190422A: Swift-BAT refined analysis
  88. LIGO/Virgo S190421ar/G330308: ANTARES neutrino search
  89. GRB 190422A: Swift-XRT refined Analysis
  90. LIGO/Virgo S190421ar: MAXI/GSC Observations
  91. LIGO/Virgo S190421ar: INTEGRAL prompt observation
  92. GRB 190422A: Enhanced Swift-XRT position
  93. GRB 190422A: Swift detection of a burst
  94. LIGO/Virgo S190421ar: Fermi-GBM Observations
  95. LIGO/Virgo S190421ar: HAWC follow-up
  96. AT LIGO-Virgo S190421ar: AGILE GRID observations
  97. LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate
  98. LIGO-Virgo S190421ar: AGILE MCAL observations
  99. LIGO/Virgo S190412m: SVOM/GWAC observations of the initial skymap
  100. Fermi Trigger 577360542 / GRB 190419414 / GRB190419A: BALROG localization

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