WD 1145+017 was observed from 2016 November through 2017 June for the purpose of further characterising the transit behaviour of the dusty debris clouds orbiting this white dwarf .
The optical observations were carried out with a small ground-based telescope run by an amateur astronomer , and covered 53 different nights over the 8-month interval .
We have found that the optical activity has increased to the highest level observed since its discovery with Kepler K2 , with approximately 17 % of the optical flux extinguished per orbit .
The source exhibits some transits with depths of up to 55 % and durations as long as two hours .
The dominant period of the orbiting dust clouds during 2016-2017 is 4.49126 hours .
We present ‘ waterfall ’ images for the entire 2016-2017 and 2015-2016 observing seasons .
In addition , the white dwarf was observed with the Chandra X-ray Observatory for 10-ksec on each of four different occasions , separated by about a month each .
The upper limit on the average X-ray flux from WD 1145+017 is \simeq 5 \times 10 ^ { -15 } ergs cm ^ { -2 } s ^ { -1 } ( unabsorbed over the range 0.1-100 keV ) , which translates to an upper limit on the X-ray luminosity , L _ { x } , of \simeq 2 \times 10 ^ { 28 } ergs s ^ { -1 } .
If L _ { x } \simeq GM _ { wd } \dot { M } _ { acc } / R _ { wd } , where M _ { wd } and R _ { wd } are the mass and radius of the white dwarf , and \dot { M } _ { acc } is the accretion rate , then \dot { M } _ { acc } \lesssim 2 \times 10 ^ { 11 } g s ^ { -1 } .
This is just consistent with the value of \dot { M } that is inferred from the level of dust activity .