Another accuracy test

Another test of accuracy: the plots show my positions for Lacrosse 4 (00-047A, #26473) obtained last night, along with positions obtained by stations 433 and 2018. The red dots are my data. The data are compared to Mike McCants elset 05420.93550308.

Station 433 uses a LL video camera, and 2018 uses stopwatch and binoculars if I am not mistaken. Note that with regard to delta T, the values should regres from negative values (satelllite early with respect to the elset) before the elset epoch to increasingly positive values (satellite late with repsect to the elset) after the elset epoch (which indeed they do).

Again, my setup seems to perform well.

Lacrosse 4

Wednesday, August 31, 2005, 00:27:31 LT

Slightly hazy, but reasonable conditions this evening.

Obtained two instead of one images of 00-047A (Lacrosse 4)
spaced 1 minute apart as it traversed Pegasus, and hence 4
points. The second pic shows the typical orange colour of the
Lacrosse satellites, due to orange metal foil covering, rather
well. The sat seemed some 0.15 seconds late relative to elset
05240.93550308

I might give Lacrosse 3 a try later tonight as well, if my
alarm clock cooperates. Yesterday it did not and I woke up 30
minutes too late....

Experimenting with a slightly different camera setting today
(other color/contrast setting). I have some idea that trails come
out better as a result.

Accuracy test - seem to do fine

Using data reported for Lacrosse 2 (91-017A, #21147) by stations 2018, 2675, 2701, 2751 and me (4352) over the past week, I analysed the accuracy of the positions relative to Mike McCants' Elset 05234.83672363, using Scott Cambell's SatFit program. The goal was to see how my own data accuracy fitted with the other stations, thus getting an indication of the performance of the setup here.

Above diagrams give the comparisons in terms of positional error, cross-track error, and timing error. Note that with regard to the error, "early" observations (those before the Aug 22 epoch date of the Elset should come out early (negative delta T), and "late" observations late (positive delta T). My station's data are shown as red dots.

Looking at the diagrams, my setup seems to perform well and I don't need to worry. Which is good to know...

Cirrus, and satellites

24 Aug 2005, 01:55 LT

Above picture is the Japanese spysat IGS 1B (03-009B, #27699) coming out of the earth shadow almost in the zenith, around 23:28:07 local time (21:28:07 UTC) this night. I saw it visually, coming out of eclipse and brightening rapidly to about mag +2.0.

Above picture resulted in a good position measured from the end point of the trail.

Conditions were rather poor this night. A pass of Lacrosse 2 (USA, 91-017A, #21147) suffered from fields of thin cirrus. The start of the trail was too ambiguous to measure, the end did yield one point.

Just like yesterday, the bank building opposite me had all the bright lights in their offices on: this while these offices were completely deserted.... This was a big nuisance, apart from being a waste of energy. I hope this is not going to be a new trend. being in the midst of a ciy allready is hard enough concerning the light pollution, and this is definitely notably decreasing my visual limiting magnitude. I have to shield my eyes against the glare!

Further analysis 91-017A (Lacrosse 2) data

Because the residual for my second point for 91-017A
of last night worried me, I ran SatFit again but this
time also incorporating my data of 17 August. These
are the results:

AZ EL ASP XTRK deltaT Perr
(1) 97.49 47.14 118.26 0.02 0.04 0.030
(2) 102.25 44.06 122.20 0.00 -0.08 0.032
(3) 91.14 49.19 114.34 0.01 0.03 0.016
(4) 96.63 46.27 118.46 0.01 0.18 0.082

Again deltaT of the last point of last night clearly
stands out. However, the results for 17 August do not
indicate this is something recurrent. Hence, it appears
the last point for last night is just anomalous. Such
can happen, it are observational data after all, which
always can have errors introduced by God-Knows-What.

Nice bright sat (Lacrosse 2)

Yesterday evening was clear (it is clouded again now),
and I catched Lacrosse 2 (#21147, 91-017A) making a very
nice pass over the rising Pegasus square at a steady
mag +2. The sat was seen visually, and the trail shows
up well on the image too. The startpoint measured was
very close to the last TLE for 21147, 05232.87066994,
the endpoint is off by some 0.15 seconds. The fit is
as follows (using Scott Campbell's SatFit):

AZ EL ASP XTRK deltaT Perr
( 1) 91.14 49.19 114.34 0.01 0.03 0.016
( 2) 96.63 46.27 118.46 0.01 0.18 0.082

Maybe this indicates there stil is some slight calibration
problem with regard to the exposure duration of the camera.

Some pictures of the equipment

Here are some webcam pictures of the equipment of Cospar station 4352 Leiden, the actual SatTrackCam. See also my detailed SatTrackCam website.

As you can see it is actually quite simple: a lap-top, a Canon Digital Ixus 400 digital camera, and (not shown here) a DCF77 radio controlled clock for accurate time keeping. The station's geographic coördinates have been obtained by GPS.

Another clear night: nice pass of Lacrosse 2

Thursday, August 18, 2005, 02:05:36 LT

A second clear night, with somewhat better sky conditions
than yesterday. Targets were the American Radar
reconnaissance satellite Lacrosse 2, and the Japanese
optical satellite IGS-1A that was also targeted yesterday.
Tried to capture USA 129 as well and indeed have a very
faint trail on the image, but too indistinct to measure
reliably. The limiting magnitude for satellites clearly is
near +3.0 for this camera setup.

Obtained two points for Lacrossse 2 and only one point for
2003-009A (IGS 1A), the start of the trail, as the end seems
to fade away and is very indistinct on the image.

By contrast, the trail for Lacrosse 2 is fat and bright. Saw
the sat make his pass visually, magnitude steady near +2.5 through
Pegasus just before entering the earth's shadow.

Clear Sky! Observed IGS 1A and IGS 1B

Wednesday, August 17, 2005, 02:04:20 LT

After a long period of clouds and rain, it was
clear this evening, although slightly hazy. A
gibbous moon was shining low in the south, the
sky background remained quite bright.

I targetted the two Japanese IGS spy satellites,
the optical satellite IGS 1A (2003-009A, #27698)
and the radar satellite IGS 1B (2003-009B,
#27699). The main purpose of both is to keep an
eye on North Korea. IGS 1B is a very nice, bright
naked eye object.

IGS 1B made a nice pass, I observed the satellite
visually as well while it was skimming Pegasus. It
was 0.6 seconds early relative to elset 05227.95069540.

The trail of the fainter IGS 1A is les well resolved
on the image due to the bright background. It was
~ 0.3 seconds early relative to elset 05277.91063071.

Promises not fullfilled....and learning C++

Yesterday in the daytime we had a thunderstorm, and it
rained cats and dogs. However, in the early evening it
fantastically cleared.

When I came out of the Eritrean restaurant 'Djebena' with
Renée at 22:15 LT, the dusk sky still was fantastically
clear. But of course, this was too good to be true...

At about 20:50 UTC, 15 minutes before a fine zenith pass
of IGS 1B and with the camera already mounted and ready,
the first clouds came in.... I did see IGS 1B through
broken cloud cover at magnitude +1 and did shoot a
picture, and it even shows up on that picture: but the
start- and endpoints of the trail are in clouds an cannot
be determined unambiguously enough to measure it...

Similarly, I lost the next target, IGS 1A, in clouds.

I did see a nice bright Perseid meteor through broken
clouds low in the sky. Normally I would be out on our
meteor observatory with the other guys of DMS team
"Delphinus" this time of the year, but other obligations
prevented me from joining in this year.

This week, wanting to have something usefull to do while
observing was impossible, I have started to learn myself
programming in C++.

Still clouded (...), and asteroids

Tuesday, August 09, 2005, 20:39:14 LT

It is still clouded. Again, I do not think tonight will
stand a chance.

About the asteroid I reported last Sunday; MPC sent the
designation K02CS9H back, but it is a 'known' object alas,
it had two one-night reports already linked. My contribution
now has been to provide another 3 nights so its orbit is more
firm now and it has made it in to the DOU today. But it does not
count as a new discovery. Such can happen.

Bad weather over there too, Shuttle postponed

Monday, August 08, 2005, 11:16:10 LT

Skies are still overcast here, but we are not the only
ones. The landing of Shuttle Discovery has just been
postponed by 24 hours because of bad weather at Kennedy
Space Center. And the Spacewatch telescope at Kitt Peak
has been closed for almost a month now because of
continuous instable weather.

I guess it's back to the NEAT archives then...

Coupled back the "comet" of yesterday to Rob Matson. He
thinks it's a bad orbital solution on a main belter.

Rainy day, Dream away....

Monday, August 08, 2005, 01:15:15 LT

Rain rain rain and a completely overcast sky now, so
I am going to call it a day (after all it is 1 hour
after midnight already...).

Spent the afternoon and evening searching for TNO's and
main belt asteroids in the NEAT image archives. Sent in
one set of astrometry on a probable new main belter to the
MPC. Also got a set of astrometry on two consecutive
nights only on another object, that result in a cometary
orbit. Alas two night is not enough to send it in to the MPC...

That's all for today, I am going to sleep.

Hunting TNO's...

Sunday, August 07, 2005, 15:30:54 LT

This ability to post through e-mail is cool....

Weather is still weird here. Rain showers the one moment,
bright clearings the other moment....

I do not give tonight much chances. Instead, I am hunting
TNO's in the NEAT archives today......

Clouds again

Saturday, August 06, 2005, 23:40:10 LT

The atmosphere is very dynamic again. Mostly cloudy during the daytime, seriously clearing just before sunset, but thin middle altitude cloud cover again when the sky had become dark enough for photography. Tried to catch USA 129 but failed due to the cloud cover.

Currently the thin middle altitude clouds seem to be gone again, but low altitude cumuli abound. I am going to give it one last try in about 10 minutes from now and if that fails I am going to call it a day.

For the visual element: here's a picture of Lacrosse 5 obtained a few days ago:



(for a larger image click here).

Lacrosse 5 is a radar spy satellite operated by the US NRO.

Dutch weather sucks! (05-06 Aug 2005 run)

It rained all day on the 5th, but the sky rather unexpectedly cleared in the evening.

When I returned from an evening with friends at about 00:30 am local time, I had some hopes I might be able to do some imagery. Back home on the lap-top I found out that I already had missed a good pass of IGS 1A, but might be able to catch Lacrosse 2 and one of the NOSS rockets later on in the night. So I set the alarm clock.

When I woke up at 3 am, the sky conditions were very dynamic. It changed from completely clear to overcast and back again in a matter of minutes. It was clear imaging would become a gamble.

I lost the gamble: cloud fields passing by just at the moments the satellites made their passes...

Weather prospects for the week to come do not look good. Dutch Weather realy sucks.....