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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"

7450 results found.

  1. LIGO/Virgo S191105e: upper limits from AGILE/GRID observations
  2. LIGO/Virgo S191105e: Upper limits from Fermi-GBM Observations
  3. LIGO/Virgo S191105e: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo S191105e: Upper limits from IceCube neutrino searches
  5. GRB 191106A: Swift detection of a burst
  6. GRB 191101A: Swift detection of a burst
  7. GRB 191031D: Swift detection of a short hard burst
  8. GRB 191031C: Swift detection of a burst
  9. Swift Trigger 931484 is not a GRB
  10. Swift Trigger 931384: possible GRB 191025A
  11. GRB 191024A: Swift detection of a burst
  12. GRB 191019A: NOT optical afterglow and host association confirmation
  13. HAWC-191019A: No Neutrino Counterpart detected with ANTARES
  14. GRB 191019A: NOT optical spectroscopy of candidate counterpart
  15. GRB 191017B: Swift detection of a burst
  16. GRB 191016A: RATIR Optical and NIR Observations
  17. GRB 191011A: MASTER OT retraction.
  18. GRB 191011A: GROND Detection of the Optical/NIR afterglow
  19. GRB 191011A: Swift detection of a burst with an optical counterpart
  20. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  21. LIGO/Virgo S190930s: no counterpart candidate in the SVOM/GWAC observations
  22. LIGO/Virgo S190930s: Updated Sky Localization
  23. GRB 191004B: Swift detection of a burst with an optical counterpart
  24. LIGO/Virgo S190930t: J-GEM follow-up observation for Swift J221951-484240
  25. LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
  26. Fermi-LAT Gamma-ray Observations of IceCube-191001A
  27. IceCube-191001A: Candidate Counterparts with the Zwicky Transient Facility
  28. IceCube-191001A: Not observable by Fermi-GBM
  29. LIGO/Virgo S190930t: No neutrino candidates at Pierre Auger Observatory
  30. GRB 191001A: Swift ToO observations
  31. LIGO/Virgo S190930t: J-GEM follow-up observations for AT2019rpj
  32. GRB 191001A: KAIT Optical Upper Limit
  33. GRB 191001A: RATIR Optical and NIR Observations
  34. IceCube-191001A - IceCube observation of a high-energy neutrino candidate event
  35. GRB 191001A: DDOTI Optical Counterpart Candidate
  36. LIGO/Virgo S190924h: Correction to GCN 25905, updated sky localization for S190924h
  37. LIGO/Virgo S190930t: Upper limits on the two of the ZTF/GROWTH candidates
  38. LIGO/Virgo S190828h: Updated Sky Localization
  39. LIGO/Virgo S190814bv: VLA 6 GHz observations of 75 galaxies in the 90% localization region
  40. LIGO/Virgo S190923y: optical spectrum of MASTER detected transient
  41. LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search
  42. LIGO/Virgo S190930t: Candidates from the Zwicky Transient Facility
  43. LIGO/Virgo S190930t: Upper limits from Fermi-GBM Observations
  44. LIGO/Virgo S190930s: Upper limits from Fermi-GBM Observations
  45. LIGO/Virgo S190930t: No counterpart candidates in HAWC observations
  46. LIGO/Virgo S190930s: no counterpart candidates in AGILE-GRID observations
  47. LIGO/Virgo S190928c: Retraction of GW unmodeled transient candidate
  48. LIGO/Virgo S190930t : no neutrino counterpart candidate in ANTARES search
  49. LIGO/Virgo S190930s : no neutrino counterpart candidate in ANTARES search
  50. LIGO/Virgo S190930t: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo S190930t: Upper limits from IceCube neutrino searches
  52. LIGO/Virgo S190930s: Upper limits from IceCube neutrino searches
  53. LIGO/Virgo S190930s: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo S190828j: Updated Sky Localization
  55. LIGO/Virgo S190923y: MASTER OT outburst detection inside NSBH merger error-box
  56. GRB 190926A: KAIT Optical Upper Limit
  57. GRB 190926A: Swift detection of a burst
  58. LIGO/Virgo S190924h: Not observable by CALET
  59. LIGO/Virgo S190923y: No neutrino candidates at Pierre Auger Observatory
  60. LIGO/Virgo S190924h: Upper limits from Fermi-GBM Observations
  61. LIGO/Virgo S190924h : no neutrino counterpart candidate in ANTARES search
  62. LIGO/Virgo S190924h: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo S190924h: Upper limits from IceCube neutrino searches
  64. IceCube-190922B: Identification of a Candidate Supernova from the Zwicky Transient Facility
  65. LIGO/Virgo S190923y: Upper limits from Fermi-GBM Observations
  66. LIGO/Virgo S190814bv: Chandra X-ray non-detection of ASKAP J005547-270433 / AT2019osy
  67. LIGO/Virgo S190923y: Upper limits from AGILE-GRID observations
  68. LIGO/Virgo S190923y : no neutrino counterpart candidate in ANTARES search
  69. LIGO/Virgo S190923y: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo S190923y: No counterpart candidates in HAWC observations
  71. LIGO/Virgo S190923y: Upper limits from IceCube neutrino searches
  72. IceCube-190922B: Upper limits from Fermi-GBM Observations
  73. IceCube-190922A: Upper limits from Fermi-GBM Observations
  74. IceCube-190922B - IceCube observation of a high-energy neutrino candidate event
  75. IceCube-190922A - IceCube observation of a high-energy neutrino candidate event
  76. GRB 190919B: Swift ToO observations
  77. LIGO/Virgo S190814bv: SOAR spectroscopy of AT2019nte host galaxy
  78. LIGO/Virgo S190828l: Updated Sky Localization
  79. LIGO/Virgo S190910h: Updated Sky Localization
  80. NASA GW-EM Community Survey
  81. LIGO/Virgo S190915ak: Updated Sky Localization
  82. LIGO/Virgo S190915ak: Upper limits from Fermi-GBM Observations
  83. LIGO/Virgo S190915ak : no neutrino counterpart candidate in ANTARES search
  84. LIGO/Virgo S190915ak: Upper Limits from AGILE-GRID observations
  85. LIGO/Virgo S190915ak: No counterpart candidate in AGILE-MCAL observations
  86. LIGO/Virgo S190915ak: Upper limits from IceCube neutrino searches
  87. LIGO/Virgo S190915ak: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo S190814bv: No counterpart candidate after completion of GRAWITA VST-ESO PARANAL transient survey.
  89. LIGO/Virgo S190910d: MASTER previous detection of Gaia19eba/AT2019qam
  90. LIGO/Virgo S190910d: Gaia Photometric Alerts transient candidate
  91. LIGO/Virgo S190910d: No neutrino candidates at Pierre Auger Observatory
  92. LIGO/Virgo S190910h: Four additional candidates from the Zwicky Transient Facility
  93. LIGO/Virgo S190910d: Updated Sky Localization
  94. LIGO/Virgo S190910h: Candidates from the Zwicky Transient Facility
  95. LIGO/Virgo S190910d: AstroSat CZTI upper limits
  96. LIGO/Virgo S190910h: No counterpart candidates in HAWC observations
  97. LIGO/Virgo S190910h: Upper limits from Fermi-GBM Observations
  98. LIGO/Virgo S190910h : no neutrino counterpart candidate in ANTARES search
  99. LIGO/Virgo S190910h: Upper limits from IceCube neutrino searches
  100. LIGO/Virgo S190910h: Identification of a GW compact binary merger candidate

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