# “What was that spot in the sky?” - How to identify satellites

First of all sorry for my immense ignorance in this matter and for all the stupid things I'll say here.

Yesterday, May 22nd 2017, I removed the telescope from its dusty box1 and decided to watch Jupiter. After about 2 minutes of observation I spotted something across the sky [X-files music in background], it was a little less bright as Jupiter's "Galilean" moons2.

Below you can see an accurate [Windows Paint] reconstruction of the fact I saw in my telescope. The red line indicates the direction of the thing (from right to left outside of the telescope).

Available data to help identify the object:

Time: May 22nd, 2017 @ 22:12 UTC
My position: {
Lat: 41.720194062015096
Long: 12.713427287843729
Sea level: 540 m
}
Direction: Probably South // The direction of Jupiter from that location at that time (didn't have a compass)
Telescope: {
Focal length: 700 mm
Diameter: 60 mm
Lens: H 20 mm
}


I only have data of the ISS and Iridium insights on an Android app3 so I am here to ask if there is some tool with which I can identify by myself as many satellites as possible across the sky.

Notes:

1. Winter is not nice with observers from here
2. Not visible at naked eye
3. I can almost certainly say that the "thing" was not the ISS or one of the Iridium satellites

P.s: I will post here what the object was (with reference if possible) as soon as I identify it for curious people like me.

• One curious thing, checking the Heavens above site, Jupiter was quite well down in the SW at that time, so a LEO satellite would not have been in the sun at that time, in that direction. That would make it a lot dimmer than Jupiter's moons. – James K May 23 '17 at 21:25

This will be hard to track down. I'd suggest looking at something like SATVIEW Time Machine. I've entered the location and time you provided (I had to deviate by a few minutes to find something so maybe your time is not 100% accurate) and I can see there were a few satellites flying overhead. With enough work, you may be able to figure out which one was most likely the one you saw based on the Alt-Elev information detailed in the table.

There's plenty of other online satellite tracking websites out there, but keep in mind, most of them aren't going to have everything. And possibly, what you saw is in no database because it's a classified satellite in which case you probably won't find any record of it.

• Thank you so much!! The clock I use is only 5s late on the official GMT (I use time.is/GMT as a reference) so, combining your link with in-the-sky.org I can say...well, nothing! The most possible satellite from your reference could be SL-16 R/B but it isn't since it was on my location at about 90 deg at 22:05 UTC --- Two things that would help me are: 1) could you kindly indicate on my image where is the north? 2) What is the field of view of my telescope? – Cliff Burton May 29 '17 at 11:35
• I just calculated the field of view of my telescope as 1.1 deg I hope I'm right!! And staring at Jupiter with 4 deg for 5 minutes from 22:10 UTC to 22:15 UTC nothing else passed on screen so I can say that it was a classified telescope at 100%! ...that's a joke, it is possible but the fact that there is no official non-classified satellites tracker makes it possible at any location in every single moment (I suppose). – Cliff Burton May 29 '17 at 11:43

Was it at 2212h? Could it have been 2222h? :-) Stellarium says that GLOBALSTAR M077 passed close by and was moving in the correct direction:

However, as James K points out in a comment: the Moon wasn't above the horizon at the time you specified. Could you have got the date wrong?

To try finding it yourself with Stellarium:

• In Stellarium open the Configuration window, then click the Plugins tab.

• Look for the Satellites plugin and enable it, then configure it to show everything it can: in its Sources tab select everything, and activate labels and/or markers.

• Play with the time (hold down mouse button on up or down arrow or use wheel) and see if anything looks familiar

• I am doubtful that orbital elements from Jan 2021 will accurately predict the position of a low earth satellite in May 2017. That is too long of a time span for many effects to change the orbit in ways the calculation will not do accurately. I think you need to find orbital elements from May 2017 to calculate what object it may have been. – JohnHoltz Jan 8 at 1:52
• @JohnHoltz yes you're right. I previously thought that it would use old data, but it doesn't have access to historical elements. (Also I only noticed after posting this answer that the question was from 2017 and had only been bumped because of an edit yesterday) The only other way I can see to get historical data is to submit an orbital data request to space-track.org – Aaron F Jan 8 at 11:29