# ISRO's PSLV-C37 with 104 satellites - after 56 hours only six TLEs, which factor is greatest challenge?

It's been 24 hours 56 hours since ISRO's PSLV-C37 launched from Satish Dhawan Space Centre (SRI) at 09:28 local time (03:58 UTC).

I see satcat numbers and object names for 105 total objects; 41948 2017-008A through 42052 2017-008DJ. It looks like only six deployed satellites have TLEs so far A-F with DJ appearing to be the fourth stage of the PSLV rocket still in orbit.

24 hours 56 hours is longer than I expected for first TLEs to be released.

I'm pretty sure this is quite a challenge, and I can think up a number of them here:

• n > 100
• low optical cross-section
• no telemetry or on-board GPS fixes reported from satellite owners

Do any of these (or other) factors stand out as a primary reason why this would be so challenging? Are any of them not really a reason?

Videos below: P- and P+ views appear to be nadir and zenith cameras.

These are pretty darn cool videos - but check that your volume is not at maximum before playing. Vids similar but not the same, waiting for a single definitive video to post instead.

Also available as a Planet Labs Tweet!

• It's nice to see such a deployment not coming from the belly of a B-52 for a change, there's hope for us yet. – uhoh Feb 16 '17 at 5:13
• Those sizes are right at the edge of reliable trackability using unclassified assets. Getting accurate TLEs for a 10 cm object 500 km away is going to be tricky at best. They're barely visible. – Tristan Feb 16 '17 at 18:14
• @Tristan I'm pretty sure 88 of them will look like this soon after deployment i.stack.imgur.com/01vtm.jpg While Planet labs keep careful track of of their Doves' GPS telemetry (fourth item on my list) doves do also get TLEs. These are 3U's with unfolding panels, even 1U's get TLEs don't they? OK let's find out! – uhoh Feb 16 '17 at 23:35
• @Tristan I've just asked Are 1U cubesats sufficiently detectable to get at least minimally usefully predictive TLEs?. – uhoh Feb 16 '17 at 23:51
• If you're interested, Planet publishes their own TLEs, state vectors, and JSpOC "associations". – Chris Feb 17 '17 at 15:17