Bring Back the HP 15C Scientific Calculator

I have been working on an effort to get HP to start making the 15C, or a
similar model again. To this end I have set up a web site with a
petition. If you are like me, and would love to have a well made
calculator like the 15C again. Please take a moment to go to my web
site and sign the petition. If you have never used a 15C before the web
site will tell you why it is the best scientific calculator for everyday
use. I have been in contact with a member of the calculator planning
department at HP who is sympathetic to the cause and will argue the case
to those who make the decisions, however I need to get many more
signatures on the petition, so tell anyone you know who would also
benefit from a quality calculator like the 15C, to check out the web site.

http://hp15c.org
--
Chris W

Bring Back the HP 15C
http://hp15c.org

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If you have never used a 15C before the web
site will tell you why it is the best scientific
calculator for everyday use.

Mine is still working - on the original battery!

Ben

On 16 Jun 2004 22:30:39 GMT, (BHZellner) wrote:

If you have never used a 15C before the web
site will tell you why it is the best scientific
calculator for everyday use.

Mine is still working - on the original battery!

Ben

So is mine - on the original battery, too! But I want the HP67 back,
with the magnetic cards. I was using it with the Atlas Eclipticalis
to search for and predict occultations...

In the good old days.

Larry

sandman.got@net
(reverse . and @)

In article , Laren Dart nospam@zilch wrote:
On 16 Jun 2004 22:30:39 GMT, (BHZellner) wrote:

If you have never used a 15C before the web
site will tell you why it is the best scientific
calculator for everyday use.

Mine is still working - on the original battery!

Ben

So is mine - on the original battery, too! But I want the HP67 back,
with the magnetic cards. I was using it with the Atlas Eclipticalis
to search for and predict occultations...

I have a HP-67 which still works.....

Jean Meeus once wrote, and published, some HP-67 programs for
computing occultations. Quite naturally, the HP-67 224-byte
program memory plus its data memory of some 25 numbers was far
too insufficient to maintain a database of stars, so you could
not use the HP-67 to search for occultations in a convenient
way. You had to input the data for each star, plus the approximate
time of the occultation, to have it computed.


In the good old days.

Larry

sandman.got@net
(reverse . and @)

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

Recently (BHZellner) honored sci.astro with:
If you have never used a 15C before the web
site will tell you why it is the best scientific
calculator for everyday use.

Mine is still working - on the original battery!

Ah well woe is me, I've had to replace the batteries once (there are
three of them). Not bad for twenty three years of constant use.

On Thu, 17 Jun 2004 07:45:05 GMT, (Paul Schlyter)
wrote:

I have a HP-67 which still works.....

Jean Meeus once wrote, and published, some HP-67 programs for
computing occultations. Quite naturally, the HP-67 224-byte
program memory plus its data memory of some 25 numbers was far
too insufficient to maintain a database of stars, so you could
not use the HP-67 to search for occultations in a convenient
way. You had to input the data for each star, plus the approximate
time of the occultation, to have it computed.


In the good old days.

Ah, yes, the good old days! "Inconvenient" would be the
understatement of the century! It was the latter half of the 1970s,
and the HP-67 was all I had, except for the printed SAO, the Atlas
Eclipticalis, and a total lack of knowledge. Things are a lot harder
when you don't know what the hell you're doing. It took me a week to
write two programs (my first attempt at programming), and three weeks
to get the bugs out.

I had been timing the occultations predicted yearly in S&T, but wanted
to go a couple of magnitudes fainter, so I bought the HP-67. Using
equations in Supplement to the Ephemeris, I wrote two programs.

First, one to plot the path of the Moon in the AE every couple of
hours to identify which stars, if any, would be occulted the following
weekend. This was easy, I didn't have to interpolate the Moon's
horizontal parallax, it was just a rough check to get approximate
times and SAO numbers. (Took up a lot of weekday evenings, but I had
a very patient and understanding wife!)

The second program used the horizontal parallax and the SAO position.
It "walked the Moon" up to the star, comparing the lunar semidiameter
to the distance between the center of the disc and the star. As soon
as it went negative, I backed up, entered a smaller increment, and
continued. When I got the time down to a tenth of a second, I went to
the next star.

I eventually got to where I could match the S&T predictions for my
location, and calculated occultations for several other observing
stations to check. As soon as I felt comfortable with the process, I
added occultations of fainter stars to my reports to ILOC. Even got
back a comment on my low residuals.

This is something only a masochist would do today, but I really loved
doing it. That's probably because I'm either a fanatic nitpicker, or
a nitpicking fanatic, I've never been sure which.

Oh, yes, the HP-67. The motor in the card reader eventually died, so
I sent it to HP to fix. (Flat repair fee, $60 or $80, don't remember
which.) Worked fine for a few months, then died again. I kept it for
years for nostalgic reasons, then gave it away.

Sorry for this very long post, but I thought it might be of interest
to some younger amateur astronomers who've had computers right from
the beginning. And aren't you glad you have one now?

Larry

sandman.got@net
(reverse . and @)

On Thu, 17 Jun 2004 16:46:46 GMT, nospam@zilch (Laren Dart) wrote:

Things are a lot harder
when you don't know what the hell you're doing.

I wonder? They really get hard when you have to be rigorous and very
careful. I guess I though like you when in school.