Click to subscribe to videooccs

Companion pages to this one:
Australia/New Zealand Time Resources Page.
Timing Occultations using a PC-164C Video Camera.
Dave Gault's experiences using a PC-164C video camera.
Timing occultations using a CCD Camera.
A GPS-based timebase to replace VNG
.

David Dunham, 22 January 2001:

Portable VCR for only $87 makes video occultations cheaper:

Sam Falvo, Utica, NY, recently bought a VCR for only $87.  He has 
found that it works fine with his $79 PC-23C Supercircuits low 
light-level camera, so now a complete video setup for occultations can 
be purchased for as little as about $200.  The VCR is actually a full 
size VHS camcorder (shoulder style) with input and output RCA jacks 
and color viewfinder.  It was in a closeout sale at a local Sears 
store - you might call a Sears store in your area to see if it is 
available there.  The Sears Web site does not list it, so it is possible 
that only a few stores are selling it for this price.  Please send 
me an e-mail at dunham@erols.com if a Sears store in your area has any of 
these units for sale for $87.  If not, I will ask Sam to buy several of 
them in my name (maybe they have just a few left), and I'll sell them to 
others for cost plus shipping.

The unit operates on 9.8 volts DC.  So in order to use the 
camcorder with a 12-volt battery, Sam bought a universal voltage 
adapter at Radio Shack for $20; it can be set for 3 to 12 volts, and 
Sam found that the 10 volt setting worked fine.  It is fused for 5 
amps, and the camera specifications say it draws only 1.6 amps, so 
there should be no problem, and Sam found it works.

On the IOTAoccultations e-group, there is also a discussion 
about batteries.  For portable work, you can just use your car 
battery, but then you must be set up right next to your car.  Dale 
Ireland mentioned that he powers his PC-23C and telescope drive with 
a Kendrick 17 Amp-hr. battery, 6 x 3 x 4 inches is size.  But I 
prefer smaller batteries, such as the Portapac 5 Amp-hr. battery 
available from Pocomo Mtn. Optics; it is 6 in. long, 2.5 in. wide, 
and 6.5 inches high, including a handle.  I've had troubles with the 
larger Portapac batteries.  There are many other batteries that can 
do the job, such as motorcycle batteries and batteries used for 
fishing.  I prefer small batteries, one for each device, if 
possible.  Wayne Warren sold me a couple of 1.2 Amp-hr. batteries 
that he put in a box 5.2 in. long by by 3 in. wide and 2.6 in. high.

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David Dunham, 22 January 2001:

Video timing goals:  On the IOTAoccultation e-group list, there 
has been much discussion recently about how to precisely time 
videotaped events, with some of the mentioned solutions either quite 
expensive and/or complex.  This should not scare off visual or less 
equiped video observers.  An accuracy of 0.03 or even 1/60th 
second, while obtainable under the best conditions from video, is 
not necessary for nearly all occultation applications.

For lunar occultation timings, we would be quite happy to have the 
timings guaranteed to 0.1 second.  Although the star positions are 
now quite good with Hipparcos observations, the uncertainly in the 
lunar profile produces an error that is typically a few to several 
tenths of a second.  The Clementine mapping mission did not produce 
profile information, and the accurate laser data from that mission 
missed the lunar polar regions and was not dense enough to provide 
profile information in the "temperate" and low-latitude areas.  So 
even for total occultations, careful visual timings (accurate to 
+/-0.2 second) are still useful, while for grazing occultations 
timings to +/-half a second are useful since their accuracy is 
derived more from the geographical locations of the observers.

For asteroidal occultations, an accuracy of 2% of the central 
duration is preferred, although up to 5% is still of use, and 
astrometrically, even timings to the nearest second are useful.  
Video starts to gain an advantage for events shorter than 10 seconds 
in duration, and observers should try to observe these events with 
video or drift-scanning CCD's when they can, even if the star's 
detection is not strong (but good enough to be confident when it is 
visible).  Most asteroidal occultations are of stars of 10th mag. or 
fainter that are beyond the reach of many video systems; visual 
timings of them are better than no observations.

We await the manufacture of accurate video time insertion by WWVB 
(device being designed by Les Nagy) and by GPS (device being 
designed by Helmuth Cuno, although rather expensive devices are now 
available from Horita).  Before that, we can rely on digitization 
and computer processing to align the audio WWV (or other shortwave) 
minute tones with the video frame count, or on the Manly WWV/CHU time 
inserter that Rick Frankenburger and a few others are using to make 
time-inserted copies of tapes that have WWV or CHU in the audio but 
no accurately timed display in the video.

Clocks that set themselves from WWVB, DCF, and other long-wave 
broadcasts and show the time with an LCD display are quite 
inexpensive now, less than a good digital-tuning shortwave radio.
I tested one clock and found a rather consistent 0.10-second delay 
in the LCD displayed time, and this grew to unacceptable levels when 
the clock was cold, especially below freezing.  But more tests of 
these are needed.  It might be possible to use them with a 
camcorder, to at least 0.1-second accuracy (and probably better), by 
recording their display before and after an occultation to calibrate 
the camcorder's clock.

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Peter Nelson, 24 August 2001:

I have purchased a Supercircuits (http://www.supercircuits.com/) PC23C-E
(Pal) camera for around US$90.  (This comes with a built-in audio). I have 
purchased a small 6" security monitor (QM3400 from Jaycar 
http://www.jaycar.com.au) and with appropriate RCA plugs and a power pack 
everything was right to go.  All that was required was a clear night.  
Tonight it was clear at times, but cloud was interfering.

I firstly aimed at Mars, but the planet was saturated.  I tried turning down
the monitor brightness, but to no avail.  I will have to have a play with this as I
know people have achieved quite respectable planetary images with the camera
(see the Supercircuits web site).

As the primary goal of the camera is for asteroids I wanted to find a
limiting magnitude for my 32cm scope.  I pointed the telescope to M28 and
saw quite a number of stars across the screen.  Moving east to GSC 6848 4352
= SAO 186735, the star was quite visible on the monitor.  This star has a
Tycho magnitude of 9.67, BT=11.38 and VT=9.82.  The star is therefore quite
red (BT-VT = 1.56) and so well suited to the CCD.  I felt that I could have
seen another magnitude fainter with a star of this spectral type.

Just a little further to the east was GSC 6848 3363 = SAO 186722 which was
brighter with a Tycho magnitude of 8.81 and BT=9.01 and VT=8.83
(BT-VT=0.18).  This star was very bright on the monitor, so much so that its
glare caught my eye whilst I was aiming through the finder.  Even though it
was a hotter star, I felt that I could go 1.5 magnitudes fainter.

No more testing was possible as clouds closed in, but my first impressions
were very favorable.

I'm not sure of the brand of the chip, but it has 510x492 pixels at about
0.017mm/pixel or 17u pixels.  It is rated at 0.04 lux and the shutter is
1/60 - 1/100,000 stepless.  On my telescope of 1600mm focal length, this
chip gave a respectable 0.3 degree field.  It was easy to use my 9x60 finder
to center stars.

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Peter Nelson, 6 September 2001:

I attempted monitoring 983 Gunila with the video CCD.  There was no problem 
finding the target star and it looked quite bright on the monitor - not bad 
for mag 9.9 and a 94% moon.  I thought I could identify some nearby 11th mag 
stars as well.  I recorded the event on tape and had VNG playing into the 
microphone of the camera.

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David Dunham, 12 November 2001:

Fantastic Watec 902H camera

If you act quickly, you might be able to upgrade your 
capabilies for recording lunar Leonids, and later, all occultations.
The Watec 902H camera is highly recommended for recording 
lunar meteor impacts.  Last night, I used it for the first time to 
image the 10% sunlit Moon's dark side, recording 4 reappearances of 
stars.  It was fantastic, with incredible detail visible on the 
Earthlit dark side, and the 9th-mag. stars showing brilliantly, 
using my 8-inch Schmidt-Cass. and f6.3 focal reducing lens.  The 
Watec camera will clearly be able to record lunar impacts about 2 
magnitudes fainter than the PC-23C, and similar gains are obvious 
for lunar and asteroidal occultations as well.  It has almost the 
same performance as my image-intensified system at a fraction of the 
cost; I bought my Watec 902H from Security Products International, 
Pottstown, PA (phone 610-970-5150) for $340 + $6.63 for shipping, 
but lower costs may be available elsewhere - see the end of this 
message, which also has some more information about operating the 
camera.  The Watec 902H camera is made in Japan and widely used by 
observers there.  Contact information is available at 
http://www.watec.com but that is for the American division in Las 
Vegas; you can e-mail them at watec@watec.com to perhaps ask them 
about dealers selling the camera in other countries (you might also 
check with security camera and telescope dealers in your country). 
With my telescope, it will make it possible to observe grazes of 9th 
and probably even 10th-mag. stars during the crescent phases, giving 
more opportunities to observe these events closer to home.  It is 
also HIGHLY recommended for asteroidal occultations, making it 
possible to videorecord many more of these events than with the PC-
23C.  Visual observations of asteroidal occultations, especially of 
fainter stars, suffer greatly from always larger-than-reported 
reaction times which always complicates the analysis of those 
events; removing the "personal equation" greatly increases the value 
of those observations.  The larger area as well as the sensitivity 
helps considerably in finding the target star.  Visual observations 
of asteroidal occultations are not useless, and are encouraged at 
least to help define the path limits, but video timings are better.

     Also useful, if you have a Schmidt-Cass. telescope, for 
inceasing the area of the Moon imaged, is a focal-reducing lens; 
this also helps for asteroidal occultations (larger field of view) 
and lunar occultation reappearances.  The f6.3 focal reducer is 
available in the range of $125 to $140 or so from many telescope 
dealers.  Probably even better, for a larger field of view to image 
virtually all of the Moon's dark side, is the Meade Series 4000 CCD 
f3.3 focal reducer available for $144.95 from Focus Camera, Inc. in 
Brooklyn, NY (phone orders 888-221-0828), and probably from some 
other Meade dealers.  I just received mine today, and it fits my C-8 
since Meade and Celestron backs are the same.  I hope to try it out 
tonight and will send another message only if I have any problems 
with it.

     As mentioned in my message in early August, the Watec 902H is 
very small (32mm on a side) and operates essentially the same way as 
the common Supercircuits PC-23C (but it has just an RCA output 
rather than BNC video output, so you don't need a BNC-to-RCA 
adaptor) and is powered the same way, with 12V DC, with the same 
power cord available from Radio Shack - see details in the video 
information on the IOTA Web site at
http://www.lunar-occultations.com/iota
Don't through away your PC-23C since it's handy as a 
microphone/mixer to record sound (WWV); the Watec doesn't have a 
microphone.

Frank Anet writes, and I concur (and add some more information):
The standard high sensitivity setting on the WAT-902H is useless, as 
the noise background is very high, greatly reducing the dynamic 
range, and the sensitivity is no better than with the low setting. 
The cover on the back of the camera needs to be removed (micro-size 
Phillips screws) to get to the ultra-micro switch to change the 
sensitivity to low (the camera is extremely small and light weight). 
On the low setting, the background noise for a dark scene is still 
greater than necessary (but much reduced from the high setting and 
certainly acceptable).  I permanently set the sensitivity to low.  
When observing lunar occultations, it behaves in the same way as 
does the PC23C, so that the gain is reduced automatically if too 
much of the bright side of the moon is visible (or also if there is 
a lot of glare from the invisible bright limb). Like the PC23C, it 
has a switch to control the exposure time (either 1/60 second or 
automatic).  For dark images, these two settings give the same 
results. 
     The sensitivity is adjusted from high to low with a microswitch 
that can be reached only by taking off the back plate of the camera.  
Frank recommends a No. 00 Phillips screwdriver to remove these small 
screws; the screwdriver available in the "Radio Shack" kit works, 
according to one source.  But I was able to remove the screws with a 
No. 0 Phillips screwdriver.  With the back removed, the tiny white 
sensitivity microswitch (not labelled) is mounted on the right side 
of the right side card (looking down into the camera with the RCA 
video output jack up), about a 4th the size of the shutter on/off 
switch on the left side that is accessible through a hole in the 
back plate.  The sensitivity microswitch comes in the up (high 
sensitivity) position; just use a small object, or your fingernail, 
to push it down).  Then reattach the back plate (last night, I 
observed without the back plate on, wanting to know what would 
happen when I changed from high to low sensitivity, but after seeing 
the results, the much higher noise with high sensitivity, I'm going 
to keep it on the low setting).

More about sources for the Watec 902H:

Tony Cook wrote in Aug.:
As for prices - I hunted around on the web. The price
for the 902HS at the following site is claimed to be $350
but when I phoned up and asked they gave me a price of $320?
and the 902H was under $300.  (the 902H is recommended; tests show 
that the 902HS is noisier, but not really more sensitive for 
detecting stars, than the 902H).
http://www.4spi.com/pages/pg1.html
[this is the route I followed, but the "under $300" price doesn't 
 seem to be available now.  David]

Frank Anet wrote earlier:
I purchased a Watec video camera (WAT-902H) from Rock House Products 
International, 2 Low Avenue, Suite 205, Middletown, New York 10940, 
because of its "Ultra Low Light" ability and "Incredible Low Light 
Operation", as quoted on the Rock2000.com web site.  The price was
about $500, but that was several months ago; it is probably cheaper 
there now.

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David Dunham, 13 November 2001:

f3.3 focal reducer fine; Watec 902H for $254

The f3.3 focal reducing lens that I mentioned in my last
message works fine with my C8; I just recorded the reappearance
of 7.0-mag. ZC 1976 at only 5 deg. altitude above the
eastern horizon.  The horizontal width of the field of
view is almost 25', enough to take in most of the Moon's
dark side, and a little more of the area than I could
record with the PC-23C on my C-5 with f6.3 focal reducer
that I used for the 1999 lunar Leonids.

And from down under, Stephen Russell writes about sources
for the Watec 902H camera:

Date: Tue, 13 Nov 2001 10:01:18 +1100
To: Joan and David Dunham 
From: Stephen Russell 
Subject: Re: Worldwide lunar Leonids; fantastic Watec 902H camera

Hi David.

I did a quick web search for the GW-902H camera, and found several
places selling it for less than $300.

$290 at http://www.genwaccameras.com/gw-902h.html
$290 at http://www.securitynet.net/gw-902h__.html
$289 at http://www.aegi.com/store/genwac_GW902H.html
$290 at http://www.spysite.com/security_cameras.html
$254 at http://www.fedcenter.com/fedsites/Unilux/HotProducts.htm

That $254 price looks good.

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David Dunham, 8 December 2001:

New Supercircuits PC164C, for $130, rivals Watec 902H

If you haven't bought a Watec 902H camera yet, maybe that's good,
because the new Supercircuits PC164C is half the price, and judging
by the specifications, may be just as sensitive.  This opens up more
affordable videorecording of asteroidal and faint lunar occultations,
and possibly lunar meteor impacts - it's worth getting to eliminate
the reaction time problem with visual occultation observations.  I've
ordered the PC164C and will let you know how it compares with the 
Watec 902H as soon as I can, but that might not be until after I return 
from Costa Rica (for the Dec. 14th annular eclipse) late on Dec. 16.
The $170 portable 8-mm VCR advertized by Supercircuits may also be 
of interest.
    See http://www.supercircuits.com for more information, although
the PC164C was not mentioned there yet as of Friday.  The Supercircuits
phone number is +1-800-335-9777.  I don't know if a PAL version of
the camera is available.  Unlike the PC23C, the PC164C does not have
a microphone for audio, but if you already have a PC23C, you can use
it just for the audio in conjunction with the PC164C.
    Tom Campbell's two messages about the camera give some more
information about it.  Thanks to a few others who have also sent
me a copy of the Supercircuits postcard announcing this.
     David Dunham, IOTA

Date: Tue, 04 Dec 2001 00:20:41 -0500
From: Tom Campbell 
To: David & Joan Dunham 
Subject: A new .0003 lux CCD video camera

Hi David,

   Attached is an advertisement card image of what I received from Super
Circuits today (sorry, not attached;
I'll try to post it at http://iota.jhuapl.edu on Monday - David).

   This new super low light level camera they offer may make our current
image intensifier modules, which are heavy, bulky, and modestly expensive,
become obsolete for use in asteroid occultation work.

    More importantly it is only $129.95 and which could make a super
sensitive camera (approaching the sensitivity of our few image intensifier
systems) more affordable to many more amateur astronomers. I am reading
this as I am sending the picture file to you.  If it turns out that if we
can use it, this low cost camera has the potential of increasing the number
of observers who can video tape asteroid occultations of the fainter stars
that are below the sensitivity of our popular PC23C.

    I just went to the Super Circuits web site and this model PC164C is not
on their web pages yet, but probably will be in a few days. So since you
are in California, you probably haven't seen this mailing from Super Circuits.

Regards,
Tom

Date: Fri, 07 Dec 2001 23:46:49 -0500
From: Tom Campbell 
To: Joan and David Dunham 
Subject: My PC164C camera

Hi David,

   I went ahead and ordered it two days ago and I will receive it Dec.
11th. They were temporarily out of stock (the salesman said, "to our
surprise, the astronomers bought our initial stock in just 2 days". He
didn't specify professional or amateur or what their special interests were
for the PC164C application.  I was notified by email today that my order
was UPS departure scanned and it is on its way. They just received the
second lot of those cameras and those are already nearly sold out. I was
told by the salesman that they were on two weeks backorder and my order
would be near the top of the waiting list, but somebody there expedited the
shipment because they are selling far better than they had originally
anticipated.

   I've been trying to get better technical specifications of the PC164C,
but the salesman knew very little more than what was on their flyer. So I
went ahead and ordered on to try it out. The price is affordable and I
cannot lose with their 30 day return policy. I did find out that it has the
1/3" sized pixel array - the same pixel area as the PC23C. The 902H Watec
has a 1/2 inch pixel size and 570 line resolution. The latter will give a
sharper image than the 420 line resolution of the PC164C is all, but still
more than enough for occultation applications (the PC23C also has 420 line
resolution) and its image appears plenty sharp to me.

Tom

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David Dunham, 7 January 2002:

KPC-350BHEX (PC-164C) in other countries

In the message below, Kevin says that he can
provide sources for the inexpensive sensitive
KT&C video camera KPC-350BHEX (sold as the
PC-164C by Supercircuits in the U.S.A., as
described in previous messages) in other
countries, especially those who need PAL
(and I think SECAM) versions rather than the
NTSC version sold in the U.S.A.

Wed, 02 Jan 2002 16:48:45 -0800 (PST)
From: kevin 
Subject: Fw: KPC-350BHEX(PC-164C)
To: dunham@pop.erols.com

----- Original Message ----- From: kevin
To: eoleen@earthlink.net
Cc: dunham@pop.erols.com
Sent: Friday, December 28, 2001 PM 12:23
Subject: KPC-350BHEX(PC-164C)
Dear Edward Oleen,
I got some answers from HQ.
1) PAL version - If you specify the country, I could provide 
the contact points.
2) DC Level - Iris operation time adjustments (1/60~1/100,000: 
for NTSC, 1/50~1/100,000: for PAL)
If you need any more info, please contact us.
Happy New Year.
Kevin
Manager of Sales & Marketing
KT&C USA, Inc. aka
Korea Technology & Communications Co., Ltd.
3200 Wilshire Blvd., #1320
Los Angeles, CA 90010

T. 213-381-0061
F. 213-381-0064
www.ktncusa.com

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David Dunham, 19 January 2002:

$130 camera easily records 9th-mag. grazing occultation

Earlier tonight, I used my KT&C KPC-350BHEX camera
(better known in North America as the Supercircuits PC-164C)
camera to record 5 disappearances and 5 reappearances that
occurred during a grazing occultation of the 9.0-mag.
spectral type G0 star SAO 147050.  At my site in Hollywood,
Maryland (about 70 miles southeast of Washington, DC), the
sky was clear and conditions were good, with the 25% sunlit
waxing crescent Moon 30 deg. above the horizon and the
graze occurring at a cusp angle of 13S.  Tycho and its rays
were easily recorded on the dark side of the Earth-lit Moon.
The star had a good signal-to-noise ratio such that gradual
events could be recorded; I think I could have recorded
a graze of a star even another magnitude fainter.  I used
an 8-inch (20cm) Schimdt-Cass. telescope with f/3.3 focal
reducing lens.  This demonstrates the power of this
relatively inexpensive camera; such an event would be at the
limit of visual observation with the same telescope.  The
star is 0.5 mag. fainter than the current limit for grazes
for which IOTA supplies data, so the event had to be computed
specially with the OCCULT program.  Others with this camera
can use OCCULT to generate their own local predictions for
such faint-star grazes, but for 2003, we should extend the
limit for IOTA graze predictions to fainter stars.

I also obtained permission from a local homeowner to
set up another 8-inch SCT in his yard, and I put my Watec
902H camera on that telescope.  While there, I recorded
the disappearance of 30 Piscium (I hope that the expeditions
for the graze of that star in central Florida were successful)
and then left to set up the other telescope with the PC-164C
camera in a closed business parking lot a mile away.  But
my system to power the telescope drive at the latter location
failed and I had to manually adjust the telescope in hour
angle to make the observation with the PC-164C.  With this
problem, I did not have time to go back to the yard with
the Watec telescope to run that one remotely, as I had
hoped.  After the graze, I disconnected and then firmly
reconnected the power system for the PC-164C telescope,
and then the drive worked.

Next I want to record an asteroidal occultation with
my PC-164C.  For the Boliviana close approach last month,
I already showed that the PC-164C with the above telescope
and focal reducer can easily record 11th-mag. stars in a
dark sky, and can faintly detect 12th-mag. stars, as
described in a previous message.

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David Dunham, 22 January 2002:

Sensitive British camera rivals PC-164C

This is mainly for UK/Europeans who need a sensitive
PAL camera.  Sirko Molau in Germany notes that CCTV
Cameras in UK sells the Model 2006X camera for 69 pounds
(a little over $100 US); it uses the same 1/3" EXview HAD
Sony CCD chip that is used by the amazing Supercircuits
PC-164C camera sold in the USA.  See their Web site at
http://www.rfconcepts.co.uk/cctv-camera.htm
This should be a boon for European/UK occultation
observers who want to record faint occultations.

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David Dunham, 7 February 2002:

PC-164C records 9th-mag. graze remotely

On the morning of February 5th, I had a 2nd
success with recording a grazing occultation of a
9th-mag. star with my $130 PC-164C, this time with
an unattended remote telescope with clock drive,
camera, and camcorder running on their own while
I recorded the graze at a 2nd station about
250 meters away using my Watec 902H camera.  These
were with 8-inch SCT's with focal reducing lenses,
f/3.3 with the Supercircuits PC-164C camera and
f/6.4 with the Watec camera.  I recorded WWV time
signals with a PC-23C.  Besides my two chords,
Robert Stewart also recorded the graze with his
PC-164C on a 5-inch refractor at a site about
2 km north of my sites.
      This was a graze of the 9.1-mag. (Tycho VT
mag.) K2 star X39821 15 deg. from the south cusp
on the dark side of the 41% sunlit waning Moon,
20 deg. above the southeastern horizon.  The
observation sites were in a mainly suburban area
along VA route 654 in Berea, Virginia, about
8 km northwest of Fredericksburg and about
100 km south-southwest of Washington, DC.  The
sky was clear and it was quite chilly,
temperature about -7 deg. C. with some wind.
In spite of aiming for a good part of the profile,
Bob Stewart noticed only one long occultation,
although there may have been a second event that
he might find when reviewing his tape.  I
recorded 3 disappearances and 3 reappearances
with the Watec camera at my site.  And as
often seems to be the case, the remote site
had the best show, recording either 4 or 5
occultations of the star (I need to play back
on a large TV screen to be sure about the
5th one).  The star drifted out of the field
of view about a minute after the last reappearance.
I had to leave the star near the top of the
field of view when I left the site, to keep all
of the bright part of the Moon out of the field
of view, in a rather narrow zone where there
was little direct or reflected glare from the
bright side.  This shows that grazes of stars
significantly fainter than the IOTA Grazereg
coverage of mag. 8.5 can be recorded with the
PC-164C and equivalent cameras with the same
sensitive Sony HAD Exview CCD chips, even
when the Moon is a fat crescent.

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Rick Frankenberger, 15 February 2002:

Time inserting PAL videos with WWVH from N.Z.

The Manly inserter uses an LM1881 sync separator that works with NTSC, PAL,
or SECAM.  I don't think any modification would be necessary.

The timebase generator is an MM5369 which is obsolete.   I have a
replacement using a microprocessor that will plug into an 8 pin socket where
the MM5369 would have been.  It also allows for a course frequency
adjustment in case the crystal can't be adjusted using the variable cap in
the inserter.  I will provide the replacement part in small quantities at no
charge.

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David Dunham, 31 May 2002:

PC164C records 3 asteroidal occultations in May

Also on the Web site (http://iota.jhuapl.edu), in the section about the 
Supercircuits PC164C camera, I have added some information (bragging) 
about how I used the camera to record 3 asteroidal occultations during 
May; others have also been getting good results with it.

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David Dunham, 15 April 2002:

Modification of the Supercircuits PC-33C camera for manual gain
control.

Robert Frenzel describes and illustrates how he modified his
Supercircuits PC-33C for manual gain control.  Details are given at
http://iota.jhuapl.edu/pc33cmod.htm
Some knowledge of electronics is needed and special care is needed
due to the tiny size of the components involved.  The PC-33C is the
less sensitive color version of the PC-23C, for which a similar
modification might be possible.  But the PC-164C is made by a
different manufacturer in a different country, so a similar
modification for it would likely be different, if possible at all.

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Dave Gault, 30 July 2003:

G'day List Members,

With Sandy's permission, I'd like to pring this list up to date
with a thread that started on the IOTA list and is very "On Topic".
Apologies to members on both lists but this list need pushing
along a bit IMHO.......
**************************************************
From: "sandybumgarner"
For raw sensitivity at true video rates (60 Fields & 30 Frames per
second) the Watec (902?, 1/2" CCD) or the enhanced PC-164C (1/3" CCD) 
are top dog these days. 

In any case the Watec or enhanced 164 seem to be the best cameras for 
high sensitivity and reliable timing at 'affordable' prices.
Sandy
**************************************************
>From "DaveG"
G'day Sandy,

Am I correct to assume that these cameras are NTSC?    We in Australia
are PAL so are there equilivent cameras?

My friend receintly purchased a 0.05 lux colour camera (with 1/2 inch
chip and 600 lines) to record Mars and is happy stacking 10 images in
camera and then feeding the data straight to a frame grabber and then to
an AVI file. He has a dedicated 2 gig machine and claims he can record 
at full resolution, at full frame rate and not drop any frames.

Is going straight to PC a good idea for time sensitive applications with 
the usual Windows time issues. Do frame grabbers handle NTSC and/or/either PAL?
If I purchase a NTSC Watec or PC-164, can I get NTSC recorders in Oz?

Is surgery to the camera still required to bypass auto gain?

TIA
**************************************************
From: "sandybumgarner"
Right on, Dave ...

My 8" Ultima 2000 and enhanced PC-164C will see down to about m12 if the 
object is slightly red.  A 10" would do a bit better than that.

I looked and SuperCircuits (www.supercircuits.com) has at least one
camera that can be delivered as a PAL camera: the PC14XP.  You would have to
email them about others.

I called KT&C USA in Los Angeles and got the formal treatment.  It sounds 
like they want one to order 10,000 cameras or go jump.  I will try again
to find at least a dealer who can supply PAL versions of the PC-164C,
164-EX, 165, 180, and 182.  The NTSC PC-164C is their model number KPC-600BH and
I have seen versions 2 to 4 of that one.

Sandy Bumgarner
sandy@vbbn.com
**************************************************
Sandy asked about Ted's equipment and methods.

I asked Ted and his reply is below.......

All my Mars shots were grabbed at 640x480. The card and PC I am running it 
on (800 mhz) won't allow 640x480 capture at anything more than 10 frames a 
second unless I choose significant compression.  I try to avoid high compression 
but that is not really an issue unless you are operating at the limits of 
detection or you want to try and do very basic astrometry.

On the faster PC (2.4Ghz) I can get up to 15 frames a second at full pal
resolution ie 720x576 with minor compression.

I am thinking of getting a better capture card that will get full 25 fps
with compression ($330).  But data capture rates are enormous!  A 60
second avi file at 640x480 is about 550 megs so count on 750 megs for
full resolution.  This requires sustained (not peak) data transfers of
over 10 megs a second unless there is compression technology used.  In
the case of a better card, the compression happens in hardware and
brings the data throughput to about 6 meg per sec which is within the
capability of most current drives and PCs.

The only way you'll capture all frames at full bit depth is to record to
tape.  A VCR has poor resolution at about 240 Lines.  Your PC164C camera
is probably 380 lines so you lose out on sharpness but gain full frame
rate.

Recording to Digital camera is a better bet as you will have resolution
that exceeds PC164C output.

* A standard old analogue camera ie Video 8 will capture 300 lines
* An analogue Hi8 will get you 400-425 lines
* A digital cam will give you 500-520 lines
* A capture card will capture whatever resolution is of source.

Details on my camera is here:
http://www.allthings.com.au/Catalogue/CCS/gem%20cctv%20dsp%20video%20camera.html

software: Astrovideo, Astrostack, Registax, K3CCD
**************************************************
Anyway, that's about up to date and I hope this kicks off discussion and
comments which are always welcome......
--
Regards
Dave
http://www4.tpgi.com.au/users/daveg/index.html

[Return to Top]


David Dunham, 7 August 2003:

I'm not sure that all of your questions were answered, so I will try to do so 
- I'm just getting caught up with some old e-mail.

At 09:25 PM 7/23/2003 +1000, Dave Gault wrote:
G'day Sandy,

From: "sandybumgarner"

>For raw sensitivity at true video rates (60 Fields & 30 Frames per
>second) the Watec (902?, 1/2" CCD) or the enhanced PC-164C
>(1/3" CCD) are top dog these days.

Am I correct to assume that these cameras are NTSC?

- Yes.

    We in Australia are PAL so are there equilivent cameras?

- Yes.  There is a PAL version of the Watec camera; Andrew Elliott
in the UK and Eberhard Bredner in Germany have been using them
for a few years with good results; Dr. Bredner is in the Cc:
list, as well as others in NZ/Australia who may be able to help.
A few months ago, I asked Supercircuits if they sold a PAL version
of their PC164C and they said no, but that might have changed; that
camera is manufactured by Korean Technology Corp. and they do make
a PAL version of it.  I'm copying this to Kevin in KTC's Los Angeles
office; he might be able to point you to an Australian distributer.
There is also a company in the UK that sells a similar camera for
about 70 pounds that uses the same Sony HAD Exview CCD chip used
by the PC164C; a link to their Web site is given in my occultation
timing primer near the top of my Web site at http://iota.jhuapl.edu .

My friend receintly purchased a 0.05 lux colour camera (with 1/2 inch
chip and 600 lines) to record Mars and is happy stacking 10 images in
camera and then feeding the data straight to a frame grabber and then to
an AVI file. He has a dedicated 2 gig machine and claims he can
record at full resolution, at full frame rate and not drop any frames.

Is going straight to PC a good idea for time sensitive applications with
the usual Windows time issues.
Do frame grabbers handle NTSC and/or/either PAL?
If I purchase a NTSC Watec or PC-164, can I get NTSC recorders in Oz?

- That may be difficult, but some VCR's now can handle the different
formats (but may be rather expensive).  I think it would be best if
you could get a PAL camera to keep everything compatible with most
resources available to others in Australia.

Is surgery to the camera still required to bypass auto gain?

- yes, if you want to do that, for the PC164C and some similar cameras.
It's not crucial for most asteroidal occultations (in a uniform dark sky) 
but it helps with lunar events, especially grazing occultations where the 
bright cusp is always nearby.
     David

[Return to Top]


Geoff Hitchcox, 26 May 2004:

After the recent problem Roger Venable suffered at the hands of
his GPS, I decided to start in earnest to see what I could do to
build a next generation video OSD (On Screen Display) time
inserter - with timing redundancy built in.

I decided to go back to the drawing board, and use the fault
situations we have found over the last couple of years as a
basis to design from.

Current OSD systems are based on dedicated chips or modules to
do the high speed video. Because of the cost (and availability
issues) of these, I decided not to use them.

I also wanted to include some of the features from my PC
software called KIWI, which can cope when the GPS gives
incorrect time.

Initially I thought I would need 2 microchips to do all this.

HOWEVER - in front of me now I have the prototype "Kiwi OSD"
overlaying the video output of my DVD player with the GPS
precision time, which looks great on my widescreen TV - all done
with only ONE microchip.

I used my DVD player to generate the input video, because it
allows changing from PAL to NTSC video format for testing.

Costing of parts (single unit pricing in US$):

2.93 LM1881 video sync separator   (http://www.digikey.com)
3.05 16F628 20 MHz Microcontroller (http://www.digikey.com)
0.50 16 MHz Quartz Xtal            (http://bgm.bgmicro.com)
----
6.48  = not an expensive OSD - considering the following features:



Auto detects and operates in NTSC, PAL, SECAM and MESECAM format.

The bottom of the video screen has this format:

  HH:MM:SS EEEE OOOO FFFFF

where:

HH:MM:SS = Hours, Minutes, Seconds UTC time

EEEE     = latest Even field Vsync offset in milliseconds.

OOOO     = latest  Odd field Vsync offset in milliseconds.

FFFFF    = Contiguous field count since initial GPS sync
 - allowing 4.6 hours of NTSC video before counter rollover.

"Kiwi OSD" measures every 1PPS from the GPS, if it is out of
spec, the HH:MM:SS will thereafter flash at a 1Hz rate, alerting
the user not to trust the time, and to use the contiguous field
count for subsequent timing. If the GPS (for whatever reason)
does stammer, the camera field rate is good enough over short
periods to provide "backup" timing (see footnote #1).

Because of issues with GPS time reporting (like what happened to
Roger recently) the software goes through an extensive sync and
check before using the GPS timing data. It requires 10 self
consistent readings in full 3D (4 satellite) FIX mode before it
starts.  Thereafter, it ignores the NMEA data and only uses the
1PPS for incrementing time - which is integrity checked against
the OSD quartz timing for errors (like the Garmin 35 missing
1PPS pulse).

After you have finished the Occultation or timing run, pressing
the "info" switch causes "Kiwi OSD" to wait for the first valid
3D GPS fix, it then compares its internal clock to the GPS. If
they agree, a message "Full recording in sync with UTC" is
displayed on screen. If it does not agree "Preceding time is
SUSPECT, use Field count for timing" is scrolled on screen.

"Kiwi OSD" has full informative messages describing what is
happening, and whether there is a fault, eg "Missing 1PPS -
please check connections".

At initial and post GPS sync - the Date, Latitude, Longitude,
and satellite info is scrolled on screen.


Although the complex multitasking algorithm took 5 nights of
really hard work, the kernel code is finished - so now any
coding is just bells and whistles stuff, eg I need to remove
leading zeros etc.

There is also a lot of ROM code left for more advanced features
as well.

Boy - what a fun project, I wish I had started it a long time ago.

Roger - your recent bad experience

http://groups.yahoo.com/group/IOTAoccultations/message/7868

and

http://groups.yahoo.com/group/IOTAoccultations/message/7890

with GPS timing has finally had a good outcome!

I was going to dabble with this OSD over our Southern Winter, 
but decided to get to the prototype stage quickly to see what 
could be done, I am really pleased with initial testing - now 
for the enjoyable tinkering.

"Kiwi OSD" is a circuit that interfaces to the GPS (NMEA serial
TX, 1PPS, 5V, GND), video IN (from the camera) and video OUT
(camera video with timing overlay) that connects to the video
recording device. It does NOT require my PC KIWI project.

Kiwi OSD (once I write it up) will be a DIY experimenters hobby
project. It will require modest electronic skills and about an
hour or so to assemble. It is aimed at those that have already
spent too much money on the telescope and video gear.

Regards, Kiwi Geoff
http://www.geocities.com/kiwi_36_nz/


Footnote #1
-----------
I based my concept of using the camera field count as a "backup"
time reference on the following abridged message (#7716) by Rick
Frankenberger.

http://groups.yahoo.com/group/IOTAoccultations/message/7716

   ------------------------------------
   Measurements of VSync frequency I made in 1999 using a sync
   separator chip and a precision counter.

   Signals from camera:
   59.9383 to 59.9384 my PC-23
   -------------------------------------

Many thanks to Rick for triggering my mind to the concept of a
"backup" timebase.

Because we know that "Kiwi OSD" will be accurate to UTC (at
initial sync time), the "field counter" can be used to determine
the "field rate" of the camera timing. Then if perchance the GPS
has a "senior moment" later in the recording session, (which we
know from the blinking HH:MM:SS) we can use the field counter to
tie the beginning "known" time, to the subsequent event that
happens on field number X.

This (field counter) feature also provides a handy "double
check" that the timing numbers all make sense - even if no GPS
problems are detected.


Footnote #2
-----------
Once I have finished full beta testing, I will offer to program
the 16F628 chip. I have not worked out details at this stage,
but "initially" it will be along the lines of  - if you send me
two 628's and US$5 for p&p. I will keep one as a gift and send
you back a programmed chip with the latest version of "Kiwi OSD".

It will be limited to one per person - and the 16F628 will be
sent with copy protect enabled.

You do not need to know anything about the two IC's used, but
for the curious - you can download datasheets here:

LM1881 = Sync Separator

http://www.national.com/ds/LM/LM1881.pdf

16F628 = Microcontroller used (N.B. 4.1 Megabyte PDF)

http://ww1.microchip.com/downloads/en/DeviceDoc/40300c.pdf

[Return to Top]


Click here for a description of Brian Loader's PC-164C video occultation system.

Click here for a description of how to time occultations with a CCD.


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