Starship Asterisk*

Let's say a new magnitude +18 object appears suddenly where nothing was visible before. Approximately how long would it take for someone to find it and report it? Hours? Days? Weeks? Do some parts of the sky receive better surveillance than others? If so, what would be the range of detection times from most-observed to least-observed regions?

What if the new object was magnitude +14, +10, +6, or brighter? I assume the mean time to detection would drop rapidly, down to the range of minutes for naked eye objects.

My question is prompted by my utter fascination that supernovae in distant galaxies are detected as quickly as they are.

In the case of Comet Holmes, I assume many devoted comet watchers were watching it before it flared, so its brightening was noticed almost immediately. Do all events in the sky get discovered that quickly?

Simply stated, no.

It depends on whether the 'new object' is moving, relative to the distant stars, or not.

There are several 'potentially hazardous asteroid' projects running, which will find 'new' asteroids down to ~17 mag (if I recall correctly), within their search fields, in a day or so (depends partly on the weather, and on the phase of the Moon).

More generally, most contemporary astronomical surveys include an automatic 'detect and report transients' capability, so the speed with which any of these which are interesting objects (as opposed to, say, Iridium flares, or instrument glitches) gets noticed by an astronomer depends more on how often the pipeline output files get checked than on the recording of data. Of course, most surveys cover a very small part of the whole sky, at any one time!

There are lots of amateur astronomers looking out for novae, supernovae, comets, etc. How fast they discover any, and the relationship between the speed of discovery and magnitude, is ... complex, shall we say ...

When the LSST and Pan-STARRS come on-stream, and if they meet their design objectives, anything 'new' in approx 25-40% of the whole sky (each), down to ~20 mag, will be discovered within a week, tops (with the usual caveats re weather, phase of the Moon, scheduled maintenance, technical glitches, etc).

I am bumping this thread in case anyone else has any comments. Many thanks to those who already replied.

Javachip wrote:I am bumping this thread in case anyone else has any comments. Many thanks to those who already replied.

I too am interested in what others may have to say on this topic ...