timing technique, DRA OBS, PPAS
Walter Nissen (dk058@cleveland.Freenet.Edu)
Tue, 6 Aug 1996 14:57:38 -0400
Someone mentioned the possibility of measuring the photometric period with
respect to events other than the maxima. I think this is a technique that
can be troublesome, but occasionally worthwhile. In particular, there
have been times when I could readily distinguish a rapid (and therefore
precisely timable) drop in brightness, but could only poorly locate the
very round maxima. If the object is in a rather clear sky and near
culmination, the "plunge" event may be more useful than the maxima. But
if not, then the maxima may be more useful.
Measuring the maxima is resistant to various sources of error. You may be
able to accurately gauge the maxima even while an object passes behind a
thin cloud. The maxima may be as discernable, or more discernable, very
near the horizon as at culmination. In contrast, the plunge may slide
along the light curve, i.e, be perceived at a different phase of the light
curve, as the object rises and sets, because of variation in brightness.
A thorough technique will allow you to maximize the amount of good data
you can record. If you have a watch which can record 30 or more splits
and tape record your remarks as you observe, it will be possible to
compute a period from the maxima, as best you can judge, and also from the
plunges. You can then compare these.
I wrote at some length about the technique I use with the Casio 30-split
wristwatch, and this was printed in Flash #102, p79. Recently, my son
lent me his 100-split Timex IronMan Triathlon Indiglo 721(?) B7(?)
wristwatch. I was not nearly as pleased as I thought I would be. 100
splits are a lot of work, but also the watch is not nearly as convenient
(or at least I couldn't figure how it is). On the Casio, it takes between
1 and 1.5 seconds to reset it. If you recall, I like to start it about 4
seconds prior to an even hour. So I learned that if I merely watched the
display until it read odd:59:58.5 and reset the watch that it would then
be reset with the 4 second "guard time". I also learned that if the watch
was 6 seconds fast that I would wait until 2 seconds after odd:59:58.5, or
even:00:00.5 to perform the reset. The Timex apparently takes far longer
to reset and the amount of time varies pretty dramatically with the
history of chrono use. It may be that this problem could be resolved by
using the watch in a consistent way and measuring the longer reset
interval. But two other characteristics of the Timex turned me off.
After an hour, it throws away the fractional seconds! Whoa! That's a
tough one, forcing me to reset it just before the beginning of that
particular hour, and worse to dump the spilts out, before the hour ends.
Tough to do! This isn't supposed to be a full time job. After 100 hours
it throws away the time altogether.
My radically different reactions to these two watches may serve to alert
others to make a very careful evaluation of the usefulness of various
watches. My apologies to anyone who tried to do with a watch similar to
that Timex what I do with my Casio.
Resurs 1-3 r has now become a little difficult to measure, having fairly
round tops.
Subtract 4.06s
2 4 17.64 2 4 13.58
2 4 36.08 2 4 32.02 18.44
2 4 53.62 2 4 49.56 17.54
2 5 8.61 2 5 4.55 14.99
2 5 25.42 2 5 21.36 16.81
2 5 40.90 2 5 36.84 15.48
2 5 55.87 2 5 51.81 14.97
2 6 14.51 2 6 10.45 18.64
Total 116.87 / 7 = 16.70
96 8 Year and month (2I5)
41.3735 -81.8637 256. lat, long, hgt (3F10.0)
5 2 4 13.58 7 Start day,hr,mn,sec nbr timings
0.00 0
18.44 1
35.98 2
50.97 3
67.78 4
83.26 5
98.23 6
116.87 7
Resurs 1-3 r 10.4 3.9 0.0 4.6
1 23343U 94074 B 96214.13273442 .00000058 00000-0 95434-5 0 1813
2 23343 97.9660 271.1237 0008746 66.1191 294.0936 14.70628624 93427
PPAS(beginning):
Walter I. Nissen, Jr., CDP, dk058@cleveland.freenet.edu, 55 Barrett RD #808,
Berea, OH 44017-1657, USA, 216-243-4980, -81d 51.823', 41d 22.413', 256m, 7x35
94- 74 B 96-08-05 2: 4:13.6 WN 98.2 1. 6 16.37 A'A' or MM Resurs 1-3 r
Cheers.
---
Roger Tory Peterson - 1908-1996 - R.I.P.
Remarkable Excitement - Remarkable Talent - Remarkable Contributions