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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. GRB 190829A: Continued fading inferred from Liverpool Telescope photometry
  2. LIGO/Virgo S190814bv: SOAR spectroscopy of DECam candidate AT2019ntp
  3. GRB 190829A: Keck LRIS spectroscopy of the optical afterglow
  4. LIGO/Virgo S190828j : No significant candidates in TAROT-GRANDMA observations
  5. LIGO/Virgo S190828l: No significant candidates in TAROT-GRANDMA observations
  6. GRB 190829A: Liverpool Telescope observations
  7. GRB 190829A: TNG imaging of the NIR afterglow
  8. Fermi trigger No 588962322 Global MASTER-Net observations report
  9. GRB 190829A: NOEMA detection of the mm afterglow
  10. LIGO/Virgo S190814bv: AT2019odc and AT2019omt 10.4m GTC spectroscopy
  11. Fermi trigger No 588931056 Global MASTER-Net observations report
  12. GRB 190831A: Fermi GBM Final Real-time Localization
  13. GRB 190829A: Liverpool Telescope optical photometry
  14. GRB 190829A: UKIRT detection of the NIR Afterglow
  15. GRB 190829A: MMT detection of the optical afterglow
  16. GRB 190829A: No Neutrino Counterpart detected with ANTARES
  17. GRB 190829A: Follow up VLA and VLBI radio observations urged
  18. GRB 190829A: KAIT Detection of the Optical Afterglow
  19. GRB 190829A, Swift-BAT refined analysis
  20. GRB 190829A: AGILE-GRID upper limits
  21. GRB 190829A: AGILE ratemeters detection and MCAL upper limits
  22. GRB 190828D: Insight-HXMT/HE detection
  23. GRB 190829A: Fermi GBM detection
  24. GRB 190829A: Fermi-LAT Upper Limits
  25. GRB 190829A:: Global MASTER-net optical clear and polarization observations scheduler and some spiculations
  26. Fermi trigger No 588838851 Global MASTER-Net observations report
  27. LIGO/Virgo S190814bv: AT2019nqc and AT2019nqz 10.4m GTC spectroscopy
  28. GRB 190829A: Swift/UVOT detection of an optical afterglow with a rise
  29. GRB 190829A: GROND detection of the Optical/NIR Afterglow
  30. GRB 190829A: Swift-XRT refined Analysis
  31. GRB 190829A: Enhanced Swift-XRT position
  32. GRB190829A: Detection of VHE gamma-ray emission with H.E.S.S.
  33. GRB 190829A: 10.4m GTC spectroscopy
  34. GRB 190830B: Fermi GBM Final Real-time Localization
  35. GRB 190829A: NOT optical afterglow detection and spectroscopy
  36. LIGO/Virgo S190828j: No Counterparts in DDOTI/OAN Optical Observations
  37. GRB 190830A: Fermi GBM Final Real-time Localization
  38. GRB 190829A: GROWTH India detection of afterglow
  39. LIGO/Virgo S190828l: No counterpart candidates in KAIT observations
  40. GRB 190829A:: MASTER-net bright and decay OT detection
  41. LIGO/Virgo S190814bv: Upper limits from a two-week IceCube search for neutrinos from the direction of ASKAP J005547-270433
  42. LIGO/Virgo S190829u Global MASTER-Net observations report
  43. GRB 190829A: Dabancheng-0.5m optical afterglow detection
  44. LIGO/Virgo S190829u: Retraction of GW compact binary merger candidate
  45. Fermi trigger No 588801358 Global MASTER-Net observations report
  46. GRB 190829A: Swift detection of a burst consistent with a galaxy at z=0.08
  47. GRB 190829A: Fermi GBM Final Real-time Localization
  48. GRB 190828B: VLT/X-shooter optical afterglow candidate
  49. LIGO/Virgo S190426c: Update on Probability of Terrestrial Origin
  50. GRB 190828B: optical upper limit from 0.5m Savelli Robotic Telescope
  51. LIGO/Virgo S190828l: Upper limits from Insight-HXMT/HE observations
  52. GRB 190828B: Swift-XRT refined Analysis
  53. LIGO/Virgo S190814bv: Swift observation of ASKAP J005547-270433/AT2019osy
  54. GRB 190828B: Swift/UVOT Upper Limits
  55. LIGO/Virgo S190814bv: AT2019nxe and AT2019obc 10.4m GTC spectroscopy
  56. GRB 190828A: Swift-XRT observations
  57. GRB 190823A: AstroSat CZTI detection
  58. LIGO/Virgo S190814bv: SOAR spectroscopy of DECam candidates AT2019ntr and AT2019omx
  59. LIGO/Virgo S190814bv: VLA observation of ASKAP J005547-270433/AT2019osy
  60. LIGO/Virgo S190828l: No counterpart candidates in Fermi-LAT observations
  61. LIGO/Virgo S190828l: No transient candidates in CALET observations
  62. LIGO/Virgo S190828j: No transient candidates in CALET observations
  63. GRB 190828B: Fermi GBM observation
  64. GRB 190828B: Swift-BAT refined analysis
  65. LIGO/Virgo S190828l: no counterpart candidates in the Swift/BAT Observations
  66. LIGO/Virgo S190828j: no counterpart candidates in the Swift/BAT Observations
  67. LIGO/Virgo S190828j: No counterpart candidates in KAIT observations
  68. LIGO/Virgo S190828j: No counterpart candidates in Fermi-LAT observations
  69. GRB 190828A: Tiled Swift observations
  70. GRB 190828D: A long GRB detected by INTEGRAL
  71. Integral GRB190828.78 Global MASTER-Net observations report
  72. LIGO/Virgo S190814bv: no variation of DESGW candidates AT 2019onj and AT 2019okr from ENGRAVE VLT/HAWK-I observations, and archival detection
  73. LIGO/Virgo S190814bv: Swift UVOT - no new counterpart candidates identified
  74. GRB 190828B: Dabancheng-0.5m optical upper limit
  75. LIGO/Virgo S190828l: Upper limits from Fermi-GBM Observations
  76. LIGO/Virgo S190828j: Upper limits from Fermi-GBM Observations
  77. GRB 190828B: Enhanced Swift-XRT position
  78. GRB 190828C: BALROG localization (Fermi Trigger 588696271 / GRB 190828614)
  79. GRB 190828C: Fermi GBM Final Real-time Localization
  80. Swift GRB190828.54 Global MASTER-Net observations report
  81. GRB 190828B: Swift detection of a burst
  82. GRB 190828B: Fermi GBM Final Real-time Localization
  83. LIGO/Virgo S190828l: Upper limits from AGILE-GRID observations
  84. LIGO/Virgo S190828l: Upper limits from IceCube neutrino searches
  85. LIGO/Virgo S190828j: Upper limits from IceCube neutrino searches
  86. LIGO/Virgo S190828l Global MASTER-Net observations report
  87. LIGO/Virgo S190828l: Coverage and upper limits from MAXI/GSC observations
  88. LIGO/Virgo S190828l: No counterpart candidates in AGILE-MCAL observations
  89. LIGO/Virgo S190828j: Coverage and upper limits from MAXI/GSC observations
  90. LIGO/Virgo S190828j : no neutrino counterpart candidate in ANTARES search
  91. LIGO/Virgo S190828l : no neutrino counterpart candidate in ANTARES search
  92. LIGO/Virgo S190828j: Upper limits from AGILE-GRID observations
  93. LIGO/Virgo S190828l: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  94. LIGO/Virgo S190828j: Updated Sky Localization
  95. LIGO/Virgo S190828l: Identification of a GW compact binary merger candidate
  96. GRB 190828A: MAXI/GSC detection
  97. LIGO/Virgo S190828l: No counterpart candidates in HAWC observations
  98. LIGO/Virgo S190828j: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  99. LIGO/Virgo S190828j: No counterpart candidates in HAWC observations
  100. LIGO/Virgo S190828j: No counterpart candidates in AGILE-MCAL observations

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