High Earth Objects

I do a lot of imaging of high Earth objects and was wondering what level of interest trusat has in these positions


I don’t know about TruSat but I am interested! The techniques that TruSat has released so far would not help in tracking even “Molniya” or semi-synch objects. Certainly not geosynch objects.

That’s certainly something I’d be interested in. I’m hoping Santa Claus (Mrs Claus?) brings me a Celestron CPC1100 for Christmas, but I haven’t finalized my wish list yet so if you have some recommendations/opinions I’m all ears.

For position measurements of HEO/GEO objects I find that large aperture (read fast), medium focal-length photographic lenses work quite well. They allow you to take short exposures (10 s) using a fixed setup such that neither the stars, nor the HEO/GEO satellites trail significantly. This has the advantage that simple centroiding algorithms can be used for measuring positions. As soon as longer focal-lengths or longer exposures are used one needs to use the endpoints of either star or satellite trails, which becomes cumbersome and prone to error in the case of satellites which vary in brightness.

I’m using a 20 mega pixel DSLR with an 85mm F/1.4 lens. This gives a pixel scale of 10 arcseconds per pixel and a field-of-view of 15 by 10 degrees. I typically take sequences of 5 exposures to distinguish satellites from stars and bad pixels. Here’s a small subsection of 10 of those, using the maximum value of each pixel in those 10 frames.

It shows two geostationary satellites in inclined orbits, and a tumbling rocket booster (seen only in 4 out of 10 frames).

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@CharlesHouston is that because we would need to integrate TLEs for the incorporated observations to be useful?

The two methods you have discussed to take observations - the stop watch timing between two stars and the digital camera - are not detailed enough to allow people to get observations on geosynch objects. You seem to be very open to using any observations submitted.

By “integrate” do you mean propagate the orbit forward and backward in time? Do you mean combine observations from different sources? Certainly you have to use new observations to update parameters.

@CharlesHouston We will take observations of interest to the community - in any of the available formats IOD/UK/RDE - and do not care what method of observation was employed to achieve them. Telescopic Observations with zoom lens and DSLR (as @cgbsat describes) or an actual telescope are OK too. I personally use a Celestron RASA 8 which has a 2x3° FOV with my ZWO camera, but alas Seattle is being Seattle in November, so I haven’t posted observations recently.

I’m interested in determining observer-based calibration methods, or data-science based analyses methods which can help us accurately assess timing uncertainty and position uncertainty depending on the observation/recording method employed.

First image below is full field ~3 x 2 deg JPEG rendering of FITS image taken remotely using itelescopes T20 in New Mexico. Target was Unknown 050612 (96031 / 96531A) , tracked by hobbyists since 1996 but never matched with a known object. Additional image shows a specific track of another satellite in image (there are at least 8 easily seen), along with info to identify it.

Brad Young


Brad - And 96031 must not match an ISON object or you would have caught it. There are several low inclination geotransfer unknowns and some unknown geos as well - I am gonna compare some with my RAAN Test and see what that looks like. Charles

I am a LOT less sophisticated! I use a old Nikon D200 with a GP-1 gps unit, and my Velbon tripod. Now that I know that this setup works I am going to look for a more current DSLR to replace the D200.

It would be great to be able to quantify the error ellipsoid for our observations but that is a challenge.


I think a quick note about numbering would be useful:
NORAD (US numbering) =
1-44792 as of today normal catalog of all objects
The International numbering for each is based on launch and will be
58-002B to 19-077C
81000-89496 as of today “hobbyist” catalog maintained by space track
They do not assign INTL numbers to these
The few times I have seen these, I use the number and “T” at the end for the INTL designation, I can’t remember who suggested that
10200-134360 as of today
The ones I see, I list as ISON with number if it overlaps NORAD
I have assigned 50-XXXA to the ones I track hoping the system will be fixed by 2050
Mike McCants’ classfd.tle:
Uses NORAD and INTL if known
If unknown, uses 90xxx or 96xxx and the year + DOY + A,B,etc. for INTL
90xxx and 96xxx originated as separate lists of unknowns, I cannot remember why

I think that’s it…I will submit to seesat and make sure this right.

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