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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"

3110 results found.

  1. LIGO/Virgo S200105ae: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  2. Fermi trigger No 599761015: Global MASTER-Net observations report
  3. IceCube Alert 200101.46: Global MASTER-Net observations report
  4. IPN triangulation of GRB 191227B (short)
  5. Fermi trigger No 598988276: Global MASTER-Net observations report
  6. LIGO/Virgo S191222n : No significant candidates in FRAM-TAROT-GRANDMA observations
  7. LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
  8. LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations
  9. LIGO/Virgo S191222n: no counterpart candidates in the Swift/BAT observations
  10. Baksan Neutrino Observatory Alert 191222.09: Global MASTER-Net observations report
  11. Fermi trigger No 598648473: Global MASTER-Net observations report
  12. LIGO/Virgo S191216ap: MASTER optical observation
  13. LIGO/Virgo S191216ap : No significant candidates in FRAM-TAROT-GRANDMA observations
  14. LIGO/Virgo S191213g: No counterpart candidate in the NOWT observations
  15. LIGO/Virgo S191215w : No significant candidates in TAROT - FRAM - GRANDMA observations.
  16. LIGO/Virgo S191216ap: no counterpart candidates in the Swift/BAT observations
  17. LIGO/Virgo S191216ap: No Candidates from the Zwicky Transient Facility
  18. LIGO/Virgo S191216ap: Coverage and upper limits from MAXI/GSC observations
  19. LIGO/Virgo S191216ap: Upper limits from Fermi-GBM Observations
  20. LIGO/Virgo S191215w: no counterpart candidates in the Swift/BAT observations
  21. LIGO/Virgo S191215w: Global MASTER-Net observations report
  22. LIGO/Virgo S191213g: Additional candidates from the Zwicky Transient Facility
  23. LIGO/Virgo S191213g: Lulin Follow-up Observations of ZTF19acykzsk/AT2019wqj
  24. LIGO/Virgo S191213g: Candidates from the Zwicky Transient Facility
  25. LIGO/Virgo S191213g: no counterpart candidates in the Swift/BAT observations
  26. LIGO/Virgo S191213g: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  27. LIGO/Virgo S191205ah: no counterpart candidate in SVOM/GWAC observations
  28. LIGO/Virgo S191205ah : No significant candidates in FRAM - TAROT – GRANDMA observations
  29. LIGO/Virgo S191205ah: no counterpart candidates in the Swift/BAT observations
  30. LIGO/Virgo S191129u : No significant candidates in FRAM-TAROT-GRANDMA observations.
  31. LIGO/Virgo S191204r: No significant candidates in FRAM-TAROT-GRANDMA observations.
  32. LIGO/Virgo S191205ah: Global MASTER-Net observations report
  33. LIGO/Virgo S191204r: no counterpart candidates in the Swift/BAT observations
  34. IceCube Alert 191204.95: Global MASTER-Net observations report
  35. GRB 191203A: Fermi GBM Final Real-time Localization
  36. Fermi trigger No 596786686: Global MASTER-Net observations report
  37. Fermi trigger No 596808579: Global MASTER-Net observations report
  38. Baksan Neutrino Observatory Alert 191128.17: Global MASTER-Net observations report
  39. Baksan Neutrino Observatory Alert 191127.25: Global MASTER-Net observations report
  40. LIGO/Virgo S191124be: Global MASTER-Net observations report
  41. IceCube-191119A: No significant detection in HAWC
  42. LIGO/Virgo S191110af: Upper limits from IceCube MeV neutrino searches
  43. LIGO/Virgo S191110af: no counterpart candidates in the Swift/BAT observations
  44. LIGO/Virgo S191109d: No significant candidates in FRAM-TAROT-GRANDMA observations
  45. LIGO/Virgo S191105e: No significant candidates in FRAM-TAROT-GRANDMA observations
  46. LIGO/Virgo S191109d: no counterpart candidates in the Swift/BAT observations
  47. LIGO/Virgo S191109d: Coverage and upper limits from MAXI/GSC observations
  48. LIGO/Virgo S191105e: no counterpart candidates in the Swift/BAT observations
  49. Fermi trigger No 594592184: Global MASTER-Net observations report
  50. Trigger 933276: Swift detection of further activity from SGR 1935+2154
  51. GRB 191101A: Swift-BAT refined analysis
  52. Fermi trigger No 594563923: Global MASTER-Net observations report
  53. Fermi trigger No 594557071: Global MASTER-Net observations report
  54. GRB 191031D: Zwicky Transient Facility Follow-Up of a Swift Short GRB (Trigger 594249816/191031891)
  55. GRB 191101A: Prompt enhanced Swift-XRT position
  56. GRB 191031D: COATLI Optical Observations
  57. IPN triangulation of GRB 191025B (short)
  58. GRB 191023A: MASTER optical observation
  59. Possible GRB 191025A: FRAM-Auger optical limit
  60. Swift Trigger 931384: possible GRB 191025A
  61. Fermi trigger No 592818648: Global MASTER-Net observations report
  62. ANTARES 191011A: MASTER optical observation befor and after trigger
  63. GRB 191011A: Fermi GBM Final Real-time Localization
  64. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  65. Konus-Wind observation of GRB 191004B
  66. GRB 191004A: Optical Detection with LCO
  67. LIGO/Virgo S190930s: no counterpart candidate in the SVOM/GWAC observations
  68. LIGO/Virgo S190930t: Magellan/IMACS imaging of Swift J224718-581442 (AT2019sbk)
  69. LIGO/Virgo S190930t: Swift discovery of Swift J224718-581442 (AT2019sbk): a fading UV transient with an X-ray counterpart
  70. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO continued optical photometry
  71. GRB 191001B: Optical Upper Limits with LCO
  72. IceCube-191001A: Candidate Counterparts with the Zwicky Transient Facility
  73. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO optical photometry
  74. LIGO/Virgo S190930s: No counterpart candidates in KAIT observations
  75. LIGO/Virgo S190930t: Candidates from the Zwicky Transient Facility
  76. Fermi trigger No 591604915: Global MASTER-Net observations report
  77. LIGO/Virgo S190930s: no counterpart candidates in the Swift/BAT observations
  78. LIGO/Virgo S190930t: no counterpart candidates in the Swift/BAT observations
  79. LIGO/Virgo S190930t: Upper limits from Fermi-GBM Observations
  80. LIGO/Virgo S190930t: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  81. Fermi trigger No 591391412: Global MASTER-Net observations report
  82. Fermi trigger No 591321287: Global MASTER-Net observations report
  83. LIGO/Virgo S190923y: No significant candidates in TAROT-GRANDMA observations
  84. LIGO/Virgo S190923y: no counterpart candidates in the Swift/BAT observations
  85. LIGO/Virgo S190924h: no counterpart candidates in the Swift/BAT observations
  86. LIGO/Virgo S190923y: INTEGRAL IBIS coded-masked imaging observations of part of the localization area and further all-sky upper limits
  87. IceCube-190922B: Identification of a Candidate Supernova from the Zwicky Transient Facility
  88. LIGO/Virgo S190923y: Upper limits from IceCube neutrino searches
  89. Fermi trigger No 590777160: Global MASTER-Net observations report
  90. Baksan Neutrino Observatory Alert 190920.65: Global MASTER-Net observations report
  91. GRB 190919B: FRAM-Auger optical detection
  92. GRB 190919B: Swift-XRT observations
  93. Integral GRB190919.99: Global MASTER-Net observations report
  94. LIGO/Virgo S190915ak: No significant candidates in TAROT-GRANDMA observations
  95. LIGO/Virgo S190910h: No significant candidates in TAROT-GRANDMA observations
  96. LIGO/Virgo S190915ak: no counterpart candidates in the Swift/BAT observations
  97. LIGO/Virgo S190910d : No significant candidates in TAROT-GRANDMA observations
  98. LIGO/Virgo S190814bv: No counterpart candidate after completion of GRAWITA VST-ESO PARANAL transient survey.
  99. LIGO/Virgo S190910d and S190910h: No counterpart candidates in KAIT observations
  100. LIGO/Virgo S190910h: Four additional candidates from the Zwicky Transient Facility

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