[IAN] Re: drugs and crime replacing stars (fwd)

[Jan Hollan]

ahoj,

to o tech spektralnich brylich, viz PS dole, me privedlo na myslenku, ze
takove bryle by mel mit kazdy zajemce o fyziku a tim spise o venkovni
osvetlovani. Je to ostatne i pomucka na porovnani jasu jinak naprosto
preexponovanych (i vizualne) plosek. Ja bych jich na kartu koupil vic,
kdyby se naslo dost zajemcu, kteri si je pak u me na hvezdarne
vyzvednou. Nebo jsou nekde na ceskem trhu?

(Ten text Dr. Clarka, kolem ktereho ta korespondence je, jeste porad neni
v cistopise, ale uz by velmi brzy mel byt. Pak bude
http://svetlo.astro.cz/crime zastarale, novy text je mnohem duraznejsi i
podlozenejsi. Poznamky k te me kostrbate formulaci hypotezy o nahrade
nebe drogami atd. uvitam.)

jenik

---------- Forwarded message ----------
Date: Fri, 12 Jul 2002 16:12:16 +0200 (CEST)
From: Jan Hollan <jhollan na amper....muni.cz>
To: Barry Clark <bajc na alphalink....au>
Subject: Re: drugs and crime replacing stars

> "Hollan (2002) has suggested another possible reason for a positive indirect
> connection between lighting and crime, paraphrased here:

That's an excellent paraphrase. Much better than my sentences. Thank you. 

> Hollan, J. (2002)  Title? Drugs and crime replacing stars?
> http://amper.ped.muni.cz/jenik/letters/public  "

The URL of this (Personal communication) as I see now is
   Linkname: drugs and crime replacing stars
        URL: http://amper.ped.muni.cz/jenik/letters/public/msg00074.html

jenik

> PS On a totally different subject, do you know of Edmund Scientific?  Look
> them up on the Net.  They sell lots of stuff that would be of interest to
> planetarium visitors, eg transmission diffraction gratings in card mounts.
> Or complete rolls of ruled or holographic gratings for mounting at local
> labour rates.  I've tried to use the sheets as large aperture objective
> gratings but mounting perfection seems to be too difficult to achieve.
> Hand-held, the gratings are superb for recognising lamp types.

Thank you for this info, I did not know this supplier.

I am using foil diffraction glasses many years already, bought
occasionally (the first piece at some holography exhibition here in Brno,
the other ones by always the same stand at an Energy Efficiency Fair in
Wels, Austria -- the guy uses them to promote ``full-spectrum'' CFLs).

Your letter has been the last drop that made me to post some
another spectra I took with them in April, including a link from you,
see 
  http://amper.ped.muni.cz/light/images/vic_spectra/

Another three poor images from Venice showing that most lamps over the
main waterway are mercury ones are at
  http://amper.ped.muni.cz/light/images/hohenau_napoli/
(e.g., as a 0.25 MB one, 
  http://amper.ped.muni.cz/light/images/hohenau_napoli/fit/im002473.jpg ).

> Ask Edmunds to send you a catalog(ue).  I think they will do it for free,
> and after you have bought something they will send a new catalogue every six
> months.  Buying is easy with a Visa card, just ring them, quote the number
> and the stuff arrives within a week in my experience.  It's tough for us
> buying US stuff in US dollars ($1AUD = $0.6 USD) but I've found no other
> sources at lower prices.

If the glasses from EdSci are 5 USD per the package of six, their prices
are probably better than those of Rainbow Symphony ones, the only source I
knew before, http://www.rainbowsymphony.com. 

For a larger foil, it would be wonderful to have a blazed grating, giving
more light in some diffraction order, if it would be available I'd buy it.
Of course, keeping it in a perfect plane would be difficult. However, as I
am no photographer, for viewing stellar spectra a prism eyepiece
(cylindric galileian collimating lens -6D/-6,5 D, some strange prism I
had, small telescope) I've built years ago serves well, the image is at
  http://rady.astronomy.cz/spektra3a.htm

For streetlamps we still use a 6cm objective prism before a small
telescope to show them to the public. For stars, the area is too small to
see anything useful.