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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"
  1. LIGO/Virgo S190510g: DOAO Observation
  2. LIGO/Virgo S190510g: CALET Observations
  3. GRB 190511A: Swift/UVOT Detection
  4. LIGO/Virgo S190510g: KMTNet observation of DECam-GROWTH and DESGW candidates
  5. GRB 190511A: NOT optical afterglow
  6. LIGO/Virgo S190510g: OT MASTER142812.05-013615.2 retraction as the kilonova candidate in GCN 24490
  7. LIGO/Virgo S190510g: MASTER OT detection inside low surface brightness galaxy
  8. LIGO/Virgo S190510g: Update on candidate significance
  9. LIGO/Virgo S190510g: Las Cumbres Observatory Galaxy Targeted Counterpart Search
  10. LIGO/Virgo S190510g: Non-detection of the OT in PGC 094244
  11. LIGO/Virgo S190426c: VLA Follow-Up Observations of ZTF19aassfws
  12. LIGO/Virgo S190510g: GRAWITA REM and Loiano optical observations
  13. LIGO/Virgo S190510g: GRAWITA VST-ESO PARANAL optical observations
  14. GRB 190511A: Fermi-LAT detection
  15. GRB 190511A: Fermi GBM observation
  16. GRB 190511A: Enhanced Swift-XRT position
  17. LIGO/Virgo S190510g: DESGW counterpart candidates over 80% of the GW localization area
  18. LIGO/Virgo S190510g : Xinglong-60cm upper limit of the GRAWITA REM's OT
  19. LIGO/Virgo S190510g: MASTER OT independ detection in WISE J060606.26-353233.9 galaxy at desgw-190510a position.
  20. LIGO/Virgo S190510g: Unconfirmed OT in PGC 094244
  21. LIGO/Virgo S190510g: Dabancheng/HMT Follow-Up Observations
  22. LIGO/Virgo S190510g: Xinglong/Schmidt Follow-Up Observations
  23. LIGO/Virgo S190510g: DESGW counterpart candidate (desgw-190510a)
  24. LIGO/Virgo S190510g: Pierre Auger Observatory follow-up
  25. GRB 190511A: Swift detection of a burst
  26. GRB 190511A: Fermi GBM Final Real-time Localization
  27. LIGO/Virgo S190510g: MASTER possible OT in PGC094244 galaxy
  28. LIGO/Virgo S190510g: Insight-HXMT/HE updated observation
  29. LIGO/Virgo S190510g: SOAR/Goodman follow-up observations
  30. LIGO/Virgo S190510g: Optical Counterpart Candidates from DECam-GROWTH
  31. LIGO/Virgo S190510g: KMTNet observation
  32. LIGO/Virgo S190510g: CNEOST Follow-Up Observations
  33. LIGO/Virgo S190510g: J-GEM optical/NIR follow-up observations
  34. LIGO/Virgo S190510g: Lick/KAIT Follow-Up Observations
  35. LIGO/Virgo S190510g: Updated classification and data quality report
  36. LIGO/Virgo S190510g: Lulin Optical Follow-up Observations
  37. LIGO/Virgo S190510g: Fermi-LAT search for a high-energy gamma-ray counterpart
  38. LIGO/Virgo S190425z: CAHA-GRANDMA Observation of the Swift UVOT Source
  39. LIGO-Virgo S190426c: Pan-STARRS non-detection of ZTF19aassfws
  40. LIGO-Virgo S190510g: AGILE GRID observations
  41. LIGO/Virgo S190510g: Potential host galaxies on the updated skymap from the GLADE catalog
  42. LIGO/Virgo S190510g: GRAWITA REM optical observations
  43. LIGO/Virgo S190510g: Swift/BAT Counterpart Search
  44. LIGO/Virgo S190510g: CLU/NED Galaxies in the Localization Volume
  45. Konus-Wind observation of GRB 190501A
  46. LIGO/Virgo S190510g: Insight-HXMT/HE observation
  47. LIGO/Virgo S190510g: HSC Y-band follow-up observation
  48. GRB 190510A: Fermi GBM Final Real-time Localization
  49. LIGO/Virgo S190510g: Updated localization from LIGO and Virgo data
  50. LIGO/Virgo S190510g: MAXI/GSC Observations
  51. LIGO/Virgo S190510g: ANTARES neutrino search
  52. S190510g: INTEGRAL inactive at the time of the event
  53. LIGO/Virgo S190510g: Potential host galaxies from the GLADE catalog
  54. LIGO/Virgo S190510g: Public DECam Observations
  55. LIGO/Virgo S190510g: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo S190510g: HAWC follow-up
  57. LIGO/Virgo S190426c: Archival VLASS Observations of ZTF19aassfws 14 days prior to Merger
  58. Fermi GRB190510.12 Global MASTER-Net observations report
  59. LIGO/Virgo S190510g: Fermi GBM Observations
  60. LIGO-Virgo S190510g: AGILE MCAL observations
  61. LIGO/Virgo S190510g Global MASTER-Net observations report
  62. LIGO/Virgo S190510g: IceCube Neutrino Search
  63. LIGO/Virgo S190426c: Correction to typo in GCN 24433
  64. LIGO/Virgo S190426c: INT Observations of ZTF19aassfws
  65. GRB 190508A: GOTO optical search - no counterparts
  66. LIGO/Virgo S190503bf: TAROT-GRANDMA observation report
  67. LIGO/Virgo S190426c: Discovery Channel Telescope Follow-Up of ZTF19aassfws
  68. GRB 190508B: Fermi GBM Final Real-time Localization
  69. Fermi GRB190508.81 Global MASTER-Net observations report
  70. GRB 190508A: Fermi GBM Final Real-time Localization
  71. Fermi GRB190507.71 Global MASTER-Net observations report
  72. GRB 190507B: GOTO optical counterpart search
  73. Fermi GRB190508.11 Global MASTER-Net observations report
  74. Fermi GRB190507.97 Global MASTER-Net observations report
  75. GRB 190507B: Fermi GBM Final Real-time Localization
  76. Fermi GRB190507.27 Global MASTER-Net observations report
  77. LIGO/Virgo S190426c (BHNS candidate): Implications from Numerical Relativity
  78. GRB 190501A: Swift XRT and UVOT Observations
  79. LIGO/Virgo S190426c: Konus-Wind observations
  80. LIGO/Virgo S190425z: Konus-Wind observations
  81. IceCube-190504A: MASTER optical monitoring analysis
  82. LIGO/Virgo S190503bf: AstroSat CZTI upper limits
  83. Fermi Trigger 578903308 / GRB 190507270 / GRB190507A: BALROG localization
  84. GRB 190507A: Fermi GBM Final Real-time Localization
  85. Fermi GRB190506.58 Global MASTER-Net observations report
  86. LIGO/Virgo S190426c: Update on Source Classification
  87. Search for additional neutrino events from the direction of IceCube-190504A with IceCube
  88. Search for additional neutrino events from the direction of IceCube-190503A with IceCube
  89. Update to the Fermi GBM GCN Reporting
  90. IceCube-190504A: Insight-HXMT/HE observation
  91. GRB 190501A: CALET Gamma-Ray Burst Monitor detection
  92. IceCube-190504A: Swift-XRT Follow-up Observations
  93. IceCube-190503A: Swift-XRT Follow-up Observations
  94. LIGO/Virgo S190503bf: CALET Observations
  95. Fermi GRB190505.82 Global MASTER-Net observations report
  96. Fermi-LAT Gamma-ray Observations of IceCube-190504A
  97. Search for counterpart to IceCube-190504A with ANTARES
  98. IceCube-190503A: Insight-HXMT/HE observation
  99. Fermi GRB190505.05 Global MASTER-Net observations report
  100. Fermi GRB190504.68 Global MASTER-Net observations report

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