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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

7447 results found.

  1. LIGO/Virgo S190426c: SAO optical observation
  2. LIGO/Virgo S190425z: Pierre Auger Observatory follow-up
  3. LIGO/Virgo S190426c: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo S190426c: HAWC follow-up
  5. LIGO/Virgo S190425z: Nearby Galaxies in the Updated Localization Volume
  6. LIGO/Virgo S190425z: GROND observations of AT2019ebq/PS19qp
  7. LIGO/Virgo S190425z: Updated localization from LIGO and Virgo data
  8. LIGO/Virgo S190425z: AMI-LA radio observations of two ZTF afterglow candidates.
  9. LIGO/Virgo S190425z: GOTO observations
  10. LIGO/Virgo S190425z: ZTF pre-merger limits on PS1 candidates
  11. LIGO/Virgo GW190425z: GTC spectroscopic classification of AT2019ebq/PS19qp
  12. LIGO/Virgo S190425z: CALET Observations
  13. LIGO/Virgo S190425z: KMTNet Observation
  14. LIGO/Virgo S190425z - ePESSTO+ NTT spectrum of candidate PS19qo
  15. LIGO/Virgo S190425z - ePESSTO+ NTT observations
  16. LIGO/Virgo S190425z: ZTF19aarykkb Imaging from Las Cumbres Observatory
  17. LIGO/Virgo S190425z: Liverpool Telescope spectroscopy of ZTF19aarykkb
  18. LIGO/Virgo S190425z - GROWTH-India follow-up of two ZTF candidates
  19. LIGO/Virgo S190425z - HCT spectroscopy
  20. LIGO/Virgo S190425z: STARE2 simultaneous L-band radio observations
  21. LIGO/Virgo S190425z: OVRO-LWA simultaneous low frequency radio observations of localization region
  22. LIGO/Virgo S190425z: CLU/NED Galaxies in the Localization Volume
  23. LIGO/Virgo S190425z: ZTF19aarzaod Imaging from Las Cumbres Observatory
  24. LIGO/Virgo S190425z: Candidates from the Zwicky Transient Facility
  25. LIGO/Virgo S190425z: Fermi GBM Observations
  26. LIGO/Virgo S190425z: SQUEAN Observation
  27. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  28. LIGO/VirgoS190425z: HAWC follow-up
  29. LIGO/Virgo S190425z: INTEGRAL prompt observation
  30. LIGO/Virgo S190425z: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo S190421ar/G330308: ANTARES neutrino search
  32. LIGO/Virgo S190408an: Liverpool Telescope follow-up imaging observations
  33. GRB 190422A: Swift detection of a burst
  34. LIGO/Virgo S190421ar: Fermi-GBM Observations
  35. LIGO/Virgo S190421ar: HAWC follow-up
  36. LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate
  37. LIGO/Virgo S190408an: INTEGRAL follow-up observations
  38. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  39. LIGO/Virgo S190412m: Palomar Gattini-IR Wide-field Infrared Follow-up
  40. LIGO/Virgo S190412m: GOTO optical coverage - no notable counterparts
  41. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  42. LIGO/Virgo S190412m: Fermi-GBM Observations
  43. LIGO/Virgo S190405ar: Retraction of a GW binary merger candidate
  44. LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
  45. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  46. LIGO/Virgo S190412m/G329483: ANTARES neutrino search
  47. LIGO/Virgo S190412m: HAWC follow-up
  48. LIGO/Virgo S190412m: Identification of a GW binary merger candidate
  49. LIGO/Virgo S190408an: GROND Observations of MASTER OT J154209.55-431742.2
  50. IceCube-190331A: Swift-XRT Follow-up Observations
  51. LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
  52. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  53. GRB 190409A: Swift detection of a possible burst
  54. LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
  55. LIGO/Virgo S190408an: Identification of a GW binary merger candidate
  56. Search for neutrino counterparts to GW candidate S190408an with IceCube
  57. LIGO-Virgo S190408an: HAWC follow-up
  58. GRB 190404C: Swift-XRT observations
  59. GRB 190404B: Tiled Swift observations
  60. LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
  61. GRB 190331B: Swift ToO observations
  62. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  63. MAGIC follow-up of the X-ray flares of LS I +61�303 dete
  64. Swift Trigger 895503 is not a GRB
  65. Swift Trigger 895257: Detection of GRO J2058+42 in outburst
  66. Further Chandra observations of GW170817 ~581-583 days since merger
  67. GRB 190324A: Swift/UVOT afterglow candidate
  68. Correction: Chandra observations of GW170817 ~581 days since merger
  69. Chandra observations of GW170817 ~581 days since merger
  70. Swift Trigger 894268: Detection of GRO J2058+42 in outburst
  71. GRB 190311A: Mondy optical observations
  72. GRB 190311A: Swift detection of a burst with optical counterpart
  73. GRB 190306A: Tiled Swift observations
  74. GRB 190305A: Tiled Swift observations
  75. INTEGRAL observation of IceCube-190221A
  76. IceCube-190221A: Swift-XRT Follow-up Observations
  77. GRB 190219A: CrAO and AbAO optical upper limit
  78. GRB 190220B: Kitab Observatory optical upper limit
  79. IceCube-190221A - IceCube observation of a high-energy neutrino candidate event
  80. GRB 190220B: BOOTES-4 optical observation
  81. GRB 190219A: NOT optical afterglow candidate
  82. GRB 190220A: Swift detection of a burst with an optical counterpart
  83. GRB 190219A: Swift detection of a burst
  84. GRB 190203A: COATLI Optical Observations
  85. GRB 190204A: COATLI Optical Detection of the Fading Afterglow
  86. GRB 190202A: R and I band observation from HCT
  87. GRB 190204A: Swift detection of a burst with a possible optical counterpart
  88. Swift Trigger 887541: Swift detection of Swift J1728.9-3613
  89. GRB 190203A: Koshka Zeiss-1000 optical upper limit
  90. GRB 190203A: Swift detection of a burst with an optical counterpart
  91. GRB 190202A: Swift detection of a burst with an optical counterpart
  92. Improved IPN error box for GRB 190129B
  93. GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
  94. GRB 190129B: Swift/UVOT Upper Limits
  95. GRB 190129B: ePESSTO NTT optical observations
  96. GRB 190129B: GROND possible host candidate
  97. GRB 190129B: Swift-XRT candidate afterglow detection
  98. GRB 190129B: Tiled Swift observations
  99. INTEGRAL observation of IceCube-190124A
  100. Trigger 886266: Another Swift trigger on MAXI J1348-630

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