[amsat-bb] Re: ANDE: how much time is left ?

[Jim Towler]

Hi,

I have been getting my Keps from Space-Track.org for the past year or two,
since the service came online.

My understanding is that it's the "real" one, and most or all other keps
around other web site etc are obtained from there. There are however,
restrictions on reuse of the data from Space-Track.

As at right now, the Celestrack keps are set "727" and Space-Track is "729"
with a slightly later Epoch time. However, still about 25 hours old.

I've noticed over the last few days that the ANDE Keps have updated multiple
times per day, but have stayed some 20 to 26 hours old.

Its possible that this is by intent, for legal or other sensitive
operational reasons, given the dramatic rate of change as ANDE is getting
lower.

Normally, keps for objects can be only a few hours old when they are
updated.

If you look at older copies of the AMSAT Journal, one finds articles about
"making" your own Keps, based on the known pass times, as measured over
time, and by multiple stations.

I assume that if one had a good model for the drag and other things
happening to ANDE, it would be possible to adapt the 24-hours-old Keps, and
"tweak out" the minute or so early as reported by some stations.

I imagine that Bob's students could make rather a nice project of collecting
every Keps update, and all the telemetry, and feed it into various models to
see what can be discovered.

Nothing really new here; just saying ...

As I write this, http://www.findu.com/cgi-bin/pcsat.cgi still shows
telemetry just 30 minutes ago, but NOVA is now showing ANDE is ranging
between 177 Kms and 195 Kms around the orbits. Even if the weather is fine
up at 195, it must be getting windy down at 177, so at some point soon, it
will be all too late.

Thanks ANDE, its been fun these last few days.

Regards,
Jim, ZL1TYF


-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Henk, PA3GUO
Sent: Sunday, 23 December 2007 10:50 a.m.
To: nss at mwt.net
Cc: amsat-bb at amsat.org
Subject: [amsat-bb] Re: ANDE: how much time is left ?

Hi Joe,

During the year I also used Heavens-above, but not during the last days.

I also use NOVA, which uses Celestrack, and it is still very accurate.

For my own antenna tracking SW I use celestrack as well:
http://www.celestrak.com/NORAD/elements/amateur.txt

These sets gave today accurate information within 1 minute.

Unfortunately, this site does not include ANDE, NO-61:
http://www.amsat.org/amsat-new/tools/predict/

Not sure which SW you use, but the keppler sets are there.
Just update them prior to every pass.

Please note though that in the coming hours they will become
not accurate anymore. ANDE will dive down very fast.
(more doppler, smaller footprint, earlier as the SW predicts)

Success !
Henk

> Or i wonder how up to date the stuff on heaveans above are? I have  passes
in en43 on the 23rd of 08:21  and 12:57
> cst    sound close?
>
> Joe
>
> Henk, PA3GUO wrote:
>
>>Today ANDE is at about 182 km.
>>
>>Looking at the plot, at the most one more day is left:
>>http://home.vianetworks.nl/users/hamoen/pa3guo/ande_predict_pa3guo_22dec20
07.jpg
>>
>>But it can be less.
>>
>>Henk
>>http://www.qsl.net/pa3guo