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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"

2747 results found.

  1. LIGO/Virgo S190510g: Fermi-LAT search for a high-energy gamma-ray counterpart
  2. LIGO-Virgo S190426c: Pan-STARRS non-detection of ZTF19aassfws
  3. LIGO/Virgo S190510g: GRAWITA REM optical observations
  4. IceCube-190504A: Swift-XRT Follow-up Observations
  5. IceCube-190504A - IceCube observation of a high-energy neutrino candidate event
  6. LIGO/Virgo S190503bf: Fermi-LAT search for a high-energy gamma-ray counterpart
  7. IceCube-190503A - IceCube observation of a high-energy neutrino candidate event
  8. LIGO/Virgo S190425z: Insight-HXMT observation and counterpart search
  9. LIGO/Virgo S190426c: Fermi-LAT search for a high-energy gamma-ray counterpart
  10. LIGO/Virgo S190425z: MASTER detection of the faint flare in SDSS Seyfert galaxy z = 0.09
  11. LIGO/Virgo S190425z: No Optical Detection of the Swift/UVOT Transient in ASAS-SN observations hours before and after discovery
  12. LIGO/Virgo S190425z: Further confirmation for the classification of PS19qp/AT 2019ebq as a supernova
  13. LIGO/Virgo S190425z: Lijiang 2.4-m Telescope Follow-up Observations
  14. LIGO/Virgo S190425z: Fermi-LAT search for a high-energy gamma-ray counterpart
  15. LIGO/Virgo S190426c: a possible lensed NS-NS merger
  16. LIGO/Virgo S190426c: Tentative Red Transient Candidate from Las Cumbres Observatory
  17. Baksan Neutrino Observatory Alert 190405.62: Global MASTER-Net:LIGO/Virgo S190425z: PanSTARR OT AT2019ebq/PS19qp
  18. LIGO/Virgo S190425z: J-GEM spectroscopic observations of AT2019ebq/PS19qp with Subaru/FOCAS
  19. LIGO/Virgo S190425z - ePESSTO+ NTT observations
  20. LIGO/Virgo S190425z: ATLAS observations of the S190425z skymap
  21. LIGO/Virgo S190425z: OVRO-LWA simultaneous low frequency radio observations of localization region
  22. LIGO/Virgo S190425z: INTEGRAL IBIS prompt observation
  23. LIGO/Virgo S190425z: further analysis of INTEGRAL data
  24. LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
  25. LIGO/Virgo S190425z: SAGUARO follow-up observations
  26. LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
  27. GRB 190326A: Swift XRT and UVOT follow-up observations
  28. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  29. LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
  30. IceCube-190331A: Swift-XRT Follow-up Observations
  31. GRB 190409A: ground analysis reveals a likely spurious event
  32. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  33. GRB 190409A: Swift detection of a possible burst
  34. LIGO/Virgo S190408an: SAGUARO follow-up observations
  35. Swift GRB 190331B: Further Swift-XRT observations
  36. GRB 190331B: Swift observations of a ground-detected burst
  37. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  38. Further Chandra observations of GW170817 ~581-583 days since merger
  39. Swift detection of LS I +61 303
  40. Correction: Chandra observations of GW170817 ~581 days since merger
  41. Chandra observations of GW170817 ~581 days since merger
  42. GRB 190206A: AstroSat CZTI detection
  43. GRB 190203A: Swift-BAT refined analysis
  44. GRB 190204A: Swift detection of a burst with a possible optical counterpart
  45. GRB 190202A: LCO-CTIO optical observations
  46. GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
  47. GRB 190129B: GROND possible host candidate
  48. IceCube-190124A - IceCube observation of a high-energy neutrino candidate event
  49. GRB 190114C: GMRT detection at 1.26GHz
  50. Swift ToO Instructions Update
  51. Swift ToO Website Down
  52. GRB 190114C: RATIR Optical and NIR Detections
  53. GRB 190114C: COATLI Optical Detection
  54. GRB 190114B, Swift-BAT refined analysis
  55. GRB 190114C: SPI-ACS/INTEGRAL extended emission detection
  56. GRB 190114C: Possible host galaxy in Pan-STARRS
  57. GRB 190114B: Swift detection of a burst
  58. GRB 190114A: Possible UVOT Detection
  59. GRB 190106A: optical observations, possible jet break detection
  60. Correction to the GCN circ. 23654 / GRB 190109B: Mondy optical upper limit
  61. GRB 190106A: GMG spectral results
  62. GRB 181228A: possible NOT optical detection
  63. FRB 181228: Global MASTER Net optical inspection
  64. Swift Trigger 878504 is not astrophysical
  65. MASTER: OTs detection during Fermi alert trigger 565936249 early observations
  66. GRB 181201A: VLT/FORS2 tentative spectroscopic redshift
  67. Short-duration GRB 181121.4: MASTER-Tavrida possible OT detection near the PGC galaxy during large Fermi error box inspection
  68. GRB 181123B: Keck near-infrared imaging
  69. GRB 181110A: Kanata 1.5m optical observation
  70. Fermi GRB 181105.31: Global MASTER Net optical observations
  71. GRB 181030A: Swift detection of a burst with a possible optical counterpart
  72. IceCube-181023A - IceCube observation of a high-energy neutrino candidate event
  73. GRB 181020A: Global MASTER Net OT observations
  74. IceCube-181014A - IceCube observation of a high-energy neutrino candidate event
  75. IceCube-180908A - IceCube observation of a high-energy neutrino candidate event
  76. GRB 180828A: Swift detection of a GRB or possible Galactic Transient Swift J1754.9-2548
  77. GRB 180728A: discovery of the associated supernova
  78. Swift Trigger 852625: Swift/BAT/XRT/UVOT observations
  79. GRB 180809B: CALET Gamma-Ray Burst Monitor detection
  80. Swift Trigger 852625: a possible GRB
  81. GRB 180806.94: MASTER possible OT detection in Fermi GMB trigger 555287944 error box
  82. GMRT radio detection of GRB 180720B
  83. GRB 180728B: GOTO optical search over IPN region
  84. GRB 180728B: MASTER optical observations short GRB IPN error box
  85. GRB 180720C: Swift detection of a burst or possible Galactic Transient
  86. GRB 180720B: LCO Haleakala possible bright optical candidate
  87. GRB 180715A: LCO Sutherland possible optical candidate
  88. GRB 180705A: OSN observations
  89. Konus-Wind observation of GRB 180704A
  90. GRB 180703A: LCO Sutherland possible optical candidate
  91. GRB150101B: INTEGRAL prompt gamma-ray signal from a possible GRB170817A-analogue
  92. GRB 180626C : GOTO optical observations
  93. GRB 180626B : GOTO optical observations
  94. GRB 180613A: Possible IR afterglow
  95. GRB 180613A: Possible host galaxy at XRT position, or star
  96. GRB 180529A: CALET Gamma-Ray Burst Monitor detection
  97. AGILE/MCAL detection of GRB 180529 and a possible precursor
  98. Swift Trigger 831888: a possible GRB or Galactic transient
  99. GRB 180510B: Swift detection of a burst with an optical counterpart
  100. Chandra observations of GW170817 reveal a fading afterglow

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