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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.

Advanced Search Examples (click to copy):

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

4055 results found.

  1. LIGO/Virgo S191129u: Identification of a GW compact binary merger candidate
  2. LIGO/Virgo S191124be: Global MASTER-Net observations report
  3. LIGO/Virgo S191124be: Retraction of GW compact binary merger candidate
  4. LIGO/Virgo S191120at: Retraction of GW compact binary merger candidate
  5. LIGO/Virgo S191120aj: Global MASTER-Net observations report
  6. LIGO/Virgo S191120aj: Retraction of GW compact binary merger candidate
  7. LIGO/Virgo S191117j: Retraction of GW compact binary merger candidate
  8. LIGO/Virgo S191110af: Retraction of GW unmodeled transient candidate
  9. LIGO/Virgo S191110af: Upper limits from KM3NeT MeV neutrino search.
  10. LIGO/Virgo S191110af: Upper limits from Konus-Wind observations
  11. LIGO/Virgo S191105e: Updated Sky Localization
  12. LIGO/Virgo S191110af: Potential pulsar counterparts
  13. LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found
  14. LIGO/Virgo S191110af: Upper limits from CALET observations.
  15. LIGO/Virgo S191109d: Not observable by CALET
  16. LIGO/Virgo S191110af: Upper limits from IceCube MeV neutrino searches
  17. LIGO/Virgo S191110af: no counterpart candidates in the Swift/BAT observations
  18. LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
  19. LIGO/Virgo S191110af: No neutrino counterpart candidate in ANTARES search
  20. LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
  21. LIGO/Virgo S191110af: upper limits from AGILE/MCAL observations
  22. LIGO/Virgo S191110af: Evryscope observation report, no counterpart candidates
  23. LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, prompt observation
  24. LIGO/Virgo S191110af: Upper limits from Fermi-GBM Observations
  25. LIGO/Virgo S191110af: Coverage and upper limits from MAXI/GSC observations
  26. LIGO/Virgo S191110af: Identification of a GW unmodeled transient candidate
  27. LIGO/Virgo S191110af: Upper limits from IceCube neutrino searches
  28. LIGO/Virgo S191110af: Global MASTER-Net observations report
  29. LIGO/Virgo S191109d: No significant candidates in FRAM-TAROT-GRANDMA observations
  30. LIGO/Virgo S191110x: Retraction of GW compact binary merger candidate
  31. LIGO/Virgo S191110x: Global MASTER-Net observations report
  32. LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
  33. LIGO/Virgo S191105e: No significant candidates in FRAM-TAROT-GRANDMA observations
  34. LIGO/Virgo S191105e: Upper limits from Insight-HXMT/HE observations
  35. LIGO/Virgo S191109d: AstroSat CZTI upper limits
  36. LIGO/Virgo S191109d: no counterpart candidates in the Swift/BAT observations
  37. LIGO/Virgo S191109d : no neutrino counterpart candidate in ANTARES search
  38. LIGO/Virgo S191109d: Global MASTER-Net observations report
  39. LIGO/Virgo S191109d: upper limits from AGILE-GRID observations mailed-by:
  40. LIGO/Virgo S191109d: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
  41. LIGO/Virgo S191109d: upper limits from AGILE/MCAL observations
  42. LIGO/Virgo S191109d: Upper limits from Fermi-GBM Observations
  43. LIGO/Virgo S191109d: Coverage and upper limits from MAXI/GSC observations
  44. LIGO/Virgo S191109d: Upper limits from IceCube neutrino searches
  45. LIGO/Virgo S191109d: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo S191105e: AstroSat CZTI upper limits
  47. LIGO/Virgo S191105e: Not observable by CALET
  48. LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
  49. LIGO/Virgo S191105e: Coverage and upper limits from MAXI/GSC observations
  50. LIGO/Virgo S191105e: no counterpart candidates in the Swift/BAT observations
  51. LIGO/Virgo S191105e : no neutrino counterpart candidate in ANTARES search
  52. LIGO/Virgo S191105e: No counterpart candidates in HAWC observations
  53. LIGO/Virgo S191105e: No counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  54. LIGO/Virgo S191105e: upper limits from AGILE/GRID observations
  55. LIGO/Virgo S191105e: Upper limits from Fermi-GBM Observations
  56. LIGO/Virgo S191105e: Global MASTER-Net observations report
  57. LIGO/Virgo S191105e: upper limits from AGILE/MCAL observations
  58. LIGO/Virgo S191105e: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo S191105e: Upper limits from IceCube neutrino searches
  60. GCN Circ. 26044 and 26047 are mistakenly submission GRB reports
  61. LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
  62. LIGO/Virgo S190930s: no counterpart candidate in the SVOM/GWAC observations
  63. LIGO/Virgo S190930s: Updated Sky Localization
  64. LIGO/Virgo S190930t: Magellan/IMACS imaging of Swift J224718-581442 (AT2019sbk)
  65. LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
  66. LIGO/Virgo S190930t: Swift discovery of Swift J224718-581442 (AT2019sbk): a fading UV transient with an X-ray counterpart
  67. LIGO/Virgo S190930t: Swift J221951-484240 optical photometry of Chilescope observatory
  68. LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
  69. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO continued optical photometry
  70. LIGO/Virgo S190930t: J-GEM follow-up observation for Swift J221951-484240
  71. LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
  72. LIGO/Virgo S190930t: Upper limits from Insight-HXMT/HE observations
  73. LIGO/Virgo S190930s: Upper limits from Insight-HXMT/HE observations
  74. LIGO/Virgo S190930t: Palomar 200-in DBSP spectroscopy of ZTF19acbwaah
  75. LIGO/Virgo S190930t: AT2019rpn, AT2019rpj CrAO optical photometry
  76. LIGO/Virgo S190930t: No neutrino candidates at Pierre Auger Observatory
  77. LIGO/Virgo S190930t: ATLAS Forced photometry of ZTF19acbpqlh (AT2019rpn)
  78. LIGO/Virgo S190930t: Candidates from ATLAS observations and constraints on AT2019rpr and AT2019rpn
  79. LIGO/Virgo S190930t: Palomar 200-in DBSP follow-up of ZTF19acbpqlh and ATLAS19wyn
  80. LIGO/Virgo S190930t: J-GEM follow-up observations for AT2019rpj
  81. LIGO/Virgo S190930t: HCT observations of ZTF19acbpsuf
  82. LIGO/Virgo S190930t: Lulin Follow-up Observations of AT2019rpn and AT2019rpj
  83. LIGO/Virgo S190930s: no counterpart candidates in SAGUARO/CSS observations
  84. LIGO/Virgo S190930s: No counterpart candidates in KAIT observations
  85. LIGO/Virgo S190924h: Correction to GCN 25905, updated sky localization for S190924h
  86. LIGO/Virgo S190930t and S190930s: MASTER OT J205529.78+220725.5/AT2019rpr further analysis
  87. LIGO/Virgo S190930t: Upper limits on the two of the ZTF/GROWTH candidates
  88. LIGO/Virgo S190828h: Updated Sky Localization
  89. LIGO/Virgo S190814bv: VLA 6 GHz observations of 75 galaxies in the 90% localization region
  90. LIGO/Virgo S190923y: optical spectrum of MASTER detected transient
  91. LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search
  92. LIGO/Virgo S190930t and S190930s: MASTER PSN in unknown disk galaxy
  93. LIGO/Virgo S190930t: Candidates from the Zwicky Transient Facility
  94. LIGO/Virgo S190930t: No counterpart candidates in Fermi-LAT observations
  95. LIGO/Virgo S190930t and S190930s: MASTER optical observation and optical transient
  96. LIGO/Virgo S190930s: No counterpart candidates in Fermi-LAT observations
  97. LIGO/Virgo S190930t: Upper limits from CALET observations.
  98. LIGO/Virgo S190930s: Upper limits from CALET observations.
  99. LIGO/Virgo S190930t: Coverage and upper limits from MAXI/GSC observations
  100. LIGO/Virgo S190930s: no counterpart candidates in the Swift/BAT observations

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