http://www.space.com/32864-alien-megastructure-star-telescope-changes.html
Another thought is that the changes in cameras and telescopes over time is what caused the dimming of KIC 8462 to occur. Although this would be a good premise for observations using older cameras and telescopes, Kepler is state of the art equipment where any flaws found in the earlier cameras and telescopes would have found and alleviated so that better results would be achieved.
I would have to think that Kepler's highly polished mirror would alleviate any scenarios where older equipment would have attributed to the dimming of KIC 8462 due to the lenses or mirrors being inferior.
Scientists have also ruled out an enormous dust cloud as well.
In the new study, scientists pored over DASCH (Digital Access to a Sky Century @ Harvard) data. This is a collection of more than 500,000 photographic
glass
plates taken by astronomers at Harvard in Massachusetts between 1885 and 1993 that the university is digitizing.
"It is exciting that we have these century-old data, which are incredibly valuable for checks like this," study lead author Michael Hippke, an amateur astronomer from the German town of Neukirchen-Vluyn, told Space.com.
The researchers looked not only at Tabby's Star, but also at a number of comparable stars in the DASCH database. Results showed that many of these other stars experienced a drop in brightness similar to that of Tabby's Star in the 1960s.
"That indicates the drops were caused by changes in the instrumentation, not by changes in the stars' brightness," study co-author Keivan Stassun at Vanderbilt University in Nashville,
But like I mentioned Kepler is far superior to the DASCH database and therefore dimming should not be be result of the equipment.
Results showed that many of these other stars experienced a drop in brightness similar to that of Tabby's Star in the 1960s.
What other space based phenom aside from comets would cause a wide path of dimming across many other stars at around the same time?
The only thing that I can think of would be similar to blowing on a lit match. If you light a match and just let it burn it maintain a regular glow and burn rate. But if blow on it slightly the flame itself becomes smaller and irregular. Maybe something took place in space-time that placed a pressure against these series of stars similar to blowing on the lit match causing the light of the stars to dim and then return to normal.
We will know more when a spectral analysis is presented.
"Observing further dips in different colors can reveal information about the chemistry of the transiting object, which might confirm or reject a cometary origin," Hippke said.
Objects give off their spectral aura. Comets and planets each have their own unique spectral identifiers as would artificial objects would once their aura has been eliminated as not belonging to any known natural object.