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Re: [vsnet-chat 6966] Observer programs-weighing the options > Should I take advantage of the dark time and go after as many CV > observations as I can muster in a night, maybe 150 or so? That would be fine. I once visually observed more than 200 per night. > Of course, the majority of these will be negative observations, but maybe > tonight PQ And will go off or something exciting will happen. I'm sure there > are many who consider making 135 negative observations a complete waste of > time, and I must admit I find it less than rewarding on nights that nothing > exciting does happen. Without negative observations, there will be no detection of an outburst. The most infrequently outbursting dwarf novae have outburst duty cycles of a few percent to a less than 1 percent (I have this statistic somewhere im my old archive, and will show it when this becomes available). Surprisingly, WZ Sge-type dwarf novae do not have exceptionally low outburst duty cycles -- you will have a good chance to see their outbursts, in fact, the what is low is the chance to become the first positive observer :-) Taking 1% duty cycle as an average, you will need 100 negative observations to statistically catch outbursts of these stars. This seems to be quite well agree with the impression. If one were to wish for being immediately notified of these rare outbursts, one should not complain about receiving a sequence of 100 negative observations. I expect that the VSNET readers are well aware of this, and we encourage posting either negative or positive observations. > I know Taichi has lamented the loss of visual observers to CCD observing in > the past. But isn't it time I get a CCD and start contributing in some other > more 'scientifically useful' way? Yes, this usage of CCDs has been well proven to be sufficiently useful in detecting CV outbursts. The early history dates back to the early 1990's, and can be read in the vsnet-history archive. From my experience, visual monitoring by experienced observers has been equally contributing. This is probably because nightly setting-up CCDs is a rather difficult task (unless one has an automated system), and it would have reduced observable nights. In other situations, CCD observers are becoming more inclined to time-series photometry of a few objects rather than nightly monitoring many fields (possibly because some professionals would overweigh the former application by noting that the former application is scientifically more productive). I wish that these two extreme applications of CCDs would be more equally weighted and appreciated. What is important (common to visual and CCD monitoring) is to quickly inform detected outbursts; this has been well understood by visual observers, but the slight lack of this sense seems to have reduced the historical significance of CCD monitoring. Visual monitoring have had advantage specifically for this reason. > Then again, I have several hundred LPVs that I find amusing to follow. At > least I get to actually make positive observations for the most part. Is > this a better use of my telescope time for now? Helping to fill in the gaps > in light curves, especially gaps in under-observed stars like the NMO stars > seems like a worthwhile thing. Disregarding personal preference, first consult public automated light curves (such as ASAS-3). If the object is included in such automated observation program, and presently well sampled, there may be no immediate need for specifically adding the object in visual program. Many southern or equatorial "NMO objects" possibly meet this criterion. # The "NMO" abbreviation sometimes sounds like to me "No More Observation" ;-) Regards, Taichi Kato
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