Re: Flashers

[george wm turner <turnerg@indiana.edu>]

Humm; interesting.

bad flats; anything weird can be explained with bad flats

obscuring of the field of view; hence, changing reference stars &/or sky levels

forward scattering of light by a satellite; multiple events seem unlikely;
ah, unless it geo-synchronous.  

I'd insure the steadiness of the reference stars in the same observation;
ya' want to make sure they're all stable and no drift 

just asking the obvious questions;  this is a good one, Tom....

george wm turner
uits/rats @ indiana university
812 855 5156

On Sun, 18 May 2003, Tom Droege wrote:

> All my recent data measures a star only once a night.  So why not #3?  With 
> three dual telescopes running, I get everything that transits the meridian 
> once a night in V and I.
> 
> These are simultaneous brightenings in V and I.  Not necessarily the same 
> change in V and I.
> 
> These are .2 to 1 mag increases in a star measured many times 
> before.  (Otherwise the WS would not pick it up.) Sometimes I see more than 
> one in the data I have for a star.  In some cases it might be shifted by 
> 0.001 degree.  In others it matches the other measurements to 0.0002 degree 
> or better.
> 
> I have sort of assumed that these are caused by airplane trails or some 
> such.  Cosmic rays cannot do it because of the simultaneous V and I 
> requirement.
> 
> Tom Droege
> 
> 
> At 11:35 PM 5/18/03 +0930, Fraser Farrell wrote:
> >Tom Droege wrote:
> > > Are there many stars that flash?  I keep finding stars with one bright
> > > point.
> >
> >
> >TASS Press Release : the Mark IV discovers gravitational lens events....  :-)
> >
> >
> >Three of the four astronomical possibilities that come to mind can all be
> >dismissed:
> >
> >  - Pulsars. Not bright enough (optically), and they would flash many many
> >times during a single Mark IV exposure.
> >
> >  - Gamma ray burst's optical counterpart. This might explain those 
> > occasional
> >"seen once and never again" stars.
> >
> >  - Dwarf novae outbursts typically go on for hours, sometimes days. Lots of
> >these potentially detectable by TASS. But if you're taking many images per
> >night of a dwarf nova, you would see it "bright" on several consecutive
> >images.
> >
> >The fourth possibility is red dwarfs that are Flare Stars. These are
> >detectable as occasional outbursts of light & radio waves that last 10-30
> >minutes. Proxima Centauri, for example, can brighten from its usual mag 11 up
> >to mag 9 during a flare. Quite a sight if you're lucky enough to see one!
> >
> >
> >cheers,
> >
> >
> >--
> >
> >Fraser Farrell
> >
> >----------------------------------
> >http://astronomy.trilobytes.com.au
> >----------------------------------
> 
> 
>