AstroNotes 1968 November Vol: 7 issue 06

EDITORIAL . OTTAWA CENTRE MEETING . OSCILLATOR-AMPLIFIER CLOCK DRIVE FOR 12-Volt OPERATION . BRIEFS . VARIABLE STARS, COMETS, AND NOVA . CO-ORDINATORS . THE GRAZE OF LAMBDA CANCRI

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AstroNotes

The Newsletter of the Ottawa Centre, RASC

Vol. 7, No. 6 November 1968

Editor: Tom Tothill 22 Delong Dr. Ottawa 9
Circulation: Rick Lavery 1227 Morrison Dr. Ottawa 6

EDITORIAL

Peter MacKinnon found himself with so much to do this summer that he found it impossible to get out Astronotes. Our grateful thanks to him for doing a magnificent job
while he could. The September issue was put out by Gordy Grant, who does a lot for us behind the scenes. It was mostly a notice of meetings and didn't go outside the Ottawa area, but one item will bear repetition and a little amplification.

Not only did our own Fred Lossing win the Award for Mechanical Excellence at Stellafane, but our members who were there got their mugs on the front page of Sky and Telescope!

The summer has been a busy one, especially for the gang at the Quiet Site. They built a gorgeous 8-man meteor observatory, developed the "hill" for setting up telescopes, laid on Hi-Fi and bunks in the trailer, got ahead considerably with the electronics for the radio telescope, dug up numerous accessories for the Unitron from DRB Astronomy Club inventory, from where also appeared an 8½" Cassegrain for which they built a mount. Now we hear that there is a possibility of getting a 12' diameter Astrodome to put it in.

All this culminated in an enormously successful Star Party on Sept 20 where 63 were counted. Numerous telescopes were available, the night was clear and warm, and
the mosquitoes departed with full tanks after a while. Guests went from telescope to telescope looking at Comet Honda, Messier objects, and Saturn with four moons at
least. The Perrins&Grant Restaurant - "hot dog stand" is hardly the word for such a palace - did a roaring trade. Les MacDonald explained the comforts of the meteor observatory and ran an outdoor slide show. Maybe this is the reason why the Observers Group meeting in October was the largest ever with 73 in attendence.
Dr. Lossing and I tried various sites out of town for deep sky work and found the NRC meteor observatory at Springhill to be as close to town as you can be to have a really dark sky. Now there is a possibility that we may be given a key there and perhaps even somewhere to leave telescopes. There is even a move afoot to build something really big as a group project - sixteen inches might be feasible.

Another summer activity of great consequence was the untiring efforts of the Solar group under Steve Craig. So much so that when Steve asked National headquarters where
to send his observations to they said there wasn't one so would he take on the job? He would, and did, and is now trying to contact enthusiasts across the country to get
something worthwhile going.

Ken Hewitt-White's Messier Race was won by Les MacDonald after a hard battle down to the wire. About 30 others are still going and quite a few are expected to complete the list soon.

The meteor group under Les MacDonald has been going strong for every shower, major and minor, and quite a lot of Aurora have been observed and reported, correlating
with the Solar group.

We didn't get to see the slides of the General Assembly at Calgary until the October meeting, but they were marvellous. Also in October we had slides of Stellafane and got a good look at Fred Lossing's 8".

Well, that brings us pretty well up to date on news, mainly for the benefit of absent friends, so far as the Observers Group is concerned. It's just as well that the new system of pledged articles for Astronotes has not fully got into stride yet, or there might not have been room.
* * * * * * * *

OTTAWA CENTRE MEETING

The Centre met on Oct 3 to hear a highly interesting talk by Dr. G. Westerhaut, professor of Astronomy at the University of Maryland. His subject was: "New Advances in Galactic Structure Research"
* * * * * * * *

MURPHY'S LAW
"Anything that can go wrong, will."
How about the alarm clock, set for 03:20, that goes off at

OSCILLATOR-AMPLIFIER. 12 v. DC to 100 v. AC, 44-90 cps.
8-10 watts
- Hammond fil. transformer 116G25 (or 167N), 25 v.
centre-tapped, 0.5 amp.
- 0.75 mfd condenser, not electrolytic, 400 v.
- 10 v. Zener diode, Sarkis-Tarzian VR-10a
- 8.5 watt Bodine synchronous motor
NO, NC, R2, R3, - see text
All resistors ¼ watt except as noted. All capacitors in
mfd, 50 v. rating or higher except as noted.

OSCILLATOR-AMPLIFIER CLOCK DRIVE FOR 12-Volt OPERATION

Fred Lossing

In Sky and Telescope for August 1968, Terry Galloway describes an oscillator-inverter for obtaining 115 v. AC from a 24 v. battery. The oscillator is a stable unijunction transistor, giving a frequency variable over a fair range above and below 60 cycles.

The circuit opposite is a modification of Mr. Galloway's circuit to allow operation from a 12 v. car battery. The modified drive uses a pair of emitter-followers driving a pair of cheap (85¢) Motorola MJE 521 power transistors, instead of the $3.10 silicon controlled rectifiers in the original. This makes the circuit much less sensitive to the characteristics of the output transformer and motor. The combined cost of the pairs of 2N3391A and MJE521 transistors is less than that of the pair of rectifiers, so the cost is
actually reduced by using the extra two transistors.

The hand-held control box is a 1-1/8” x 2-1/8” x 3-1/4" handy-box, containing two 10 K trimpots for adjusting the drive to sidereal and lunar rates, two push-buttons and a
miniswitch. The NO (normally open) push-button gives an increased drive rate (90 cycles) and the NC (normally closed) one gives a reduced rate (44 cycles). Switch S when closed gives the sidereal rate, adjusted by R2. Opening S allows a portion of R3 to be added, slowing the drive to the lunar rate. The trimpots are mounted with their adjusting screws projecting through small holes, allowing fingernail adjustment while checking the drive rate at the eyepiece.

The battery drain is about 0.8 - 1.0 amp. when driving an 8.5 watt Bodine synchronous motor. The circuit will be useful for operation in the field, away from AC power, but
for permanent installations it can of course be operated from the AC mains by using a suitable 12 v. DC power supply.
********


BRIEFS

Calgary is sending us THE OBSERVER regularly - thanks. Five of them joined Regina (300 miles) for a graze and were just unlucky with cloud Rick Lavery has finished a 6" f/5...
Tom Tothill has built the foundation for his observatory...
Rick Salmon was top student at Hillcrest and won three scholarships to U of T in astronomy.

VARIABLE STARS, COMETS, AND NOVA

Rick Lavery

For the last year I have served as co-ordinator of
the above-mentioned fields and have found that there was
no real interest in them except for the odd few who
observed comets Ikeya-Seki and Honda.
The one and only major pre-requisite for doing serious
work in these fields is the ability to locate objects and
star fields in the sky. Ken Hewitt-White’s program of
M-object observing is the ideal way to learn to find
objects. For instance anyone who can find their way
through the Coma cluster should try observing variables
and novae. I also think that any person who can locate
upwards of 50 M-objects should be offered the opportunity
to begin an observing program (regular or irregular) in
variable stars. Only a modest instrument (or binoculars)
and a small amount of time is needed to really get started.
The co-ordinator will show you how to go from there.
The rewards of participating in this field are very
far-reaching. Many comets and novae have been discovered
while observing variables. You also become very familiar
with stellar magnitudes and I believe this is a necessity
to anyone who wants to become a serious amateur astronomer.
Visual magnitude estimates of newly discovered comets and
nova are extremely important and are sometimes very useful
to the professional. Finally, limiting magnitudes of
telescopes can easily be determined to estimate sky
conditions and telescope performance.
I have outlined the fruits of Variable Star, Comet,
and Nova programs and I can only add that if little
interest is shown these fields should be dropped from the
co-ordinators list, in line with the policies outlined by
our Chairman at the October meeting.
* * * * * * * *


CO-ORDINATORS

Solar STEVE CRAIG 232-5860
Lunar and Planetary TOM TOTHILL 749-4723
Meteors and Aurora LES MACDONALD 828-4487
Variables, Comets and Nova RICK LAVERY 828-8213
Deep Sky KEN H-WHITE 733-4949
Small Dome and Radio Astronomy DOUG O’BRIEN 733-8711
Quiet Site DON ROSS 836-2539
Instrumentation Open
Library STAN MOTT 722-0957
Coffee
KEN PERRINS 828-3672

THE GRAZE OF LAMBDA CANCRI

Tom Tothill

Six heroes and a heroine dragged themselves out of bed at 3:30 a.m., the morning of Oct 15, humped their telescopes into cars, drove hither and yon to pick up team mates, and headed south. They set up at half mile intervals on a country road through Pierces Corners not far from North Gower, forming five stations.

The angle of the graze line to the road was such that Dave Paterson and I, at the southern end, were 0.50 mile outside the graze limit and Dan Brunton at the other end
was 1.00 mile inside - precisely the recommended range.

I found the star immediately and followed it along the bright limb, clearing the last hump by only 2" arc, and on into the blackness through the time of central
graze and for 7 more minutes. I am certain that it did not go out at all.

Ken Hewitt-White was less fortunate. He was having trouble with the wind jiggling his telescope and didn't find the star until 2 minutes after central graze, but
after that time it was definitely not occulted. Les MacDonald and Debbie Wood were next in line, ¼ mile inside the limit line. Les too had trouble with the wind but found the star 1½ minutes before central graze and followed it successfully thereafter. He had a couple of "Outs" but soon realised that they only occurred in wind gusts and decided that he saw a miss too.

Rick Lavery, 5/8 mile inside, found the star early, watched it clear the last hump on the bright limb by only 1" arc at UT 10:08:30, and then followed it through to 1½ minutes after central graze time without an occultation.

Therefore he confirmed Les' conclusion and put Ken in the clear.
The only chance now lay with Dan , but he had trouble. He thought he saw the star well before graze, but on recentring it could not find it. He searched for it right
through graze time and finally spotted it 2½ minutes after, by which time it was obviously clear of the earthlit limb.

So we are regretfully unable to report any occultations to help define the limb in this unknown region, deep inside Cassini's Third Law region. We can say, however,
that there is a hole there at least 0.5" arc deep, or 2900 ft deep on the moon itself.