Thanks, but I described this very poorly! I know I can download elements (and tours,...) into the handset, but it's no use if the predictions generated are several degrees off (that's CROSS-TRACK, not just time errors,which are correctable!) If it doesn't correct for Earth rotation while waiting at the AOS point, it will point at a constant RA/dec, and can easily miss the satellite. If the observer position is computed only when going to the AOS, or when the 'Start tracking' is pushed, it will also be incorrect. Most severely for a geostationary, because they ARE actually moving ~15 degrees E (and down) per hour! Pushing Start when AOS beeps defeats my purpose of finding satellites that have uncertain elements! It should be pushed when the satellite actually enters the FOV. In SatTrack I can adjust the sensitivity of (cross-track and) timing adjustments , so that I can catch up. Since some I have a problem with my LXD55 (jumping between two positions instead of tracking) so I used the club's LX200. Problem: too few clear nights, public star shows, and too many members wanting to use the scope. But I have tracked both HEO satellites (Mean motion 2.006 with several minutes of elset error) and GEOs accurately, using SatTrack (LXSAT). -- Björn Gimle -- -- COSPAR 5917, STAR, +18.05447 (E), +59.34185 (N), 33 m -- -- COSPAR 5918 WGS84, +18.10127 (E), +59.29813 (N), 44 m -- -- COSPAR 5919, MALMA, +18.6206 (E), +59.2615 (N), 33 m -- ----- Original Message ----- From: "Robert Herrick" <rbherrick@gmail.com> To: "Björn (Large mails) Gimle" <bg_26934@glocalnet.net> Sent: Friday, April 03, 2009 6:09 AM Subject: Re: Potential Problems with Meade Software for Satellite Tracking Bjorn, One can load elsets into the Autostar software and into the handset. For LEOs I find that when the 'acquisition of signal' beep goes off one had better push the 'start' button on the handset or the scope will never catch up to the satellite (this took a while to figure out). I think the problem is worse than not just correcting for earth rotation (if that were true it could do a good job at 'tracking' geosats) but it actually moves the scope east and down over time, away from the geosat. We find that SatTrak is too slow in sending commands to the telescope to be useful, baud rate problem we suspect. How has SatTrak worked for you? I think the only solution to early/late satellites is to have the freshest TLEs. Regards, Bruce 2009/3/30 Björn (Large mails) Gimle <b.gimle@comhem.se>: > I agree (with the worst scenario)! > > I have made dozens of test runs with both LEO,HEO and GEO, and comparing > displayed positions to output from reliable prediction programs. > At first reading the display, later with an ASCOM program designed to log > time and position when pressing SPACE on a connected PC. > In all cases position errors were 1-5 degrees. > > Your theory appears correct - it could also explain my suspicion that it > doesn't correct for Earth rotation - noticable if the satellite is > considerably early or late. > (Which was my primary reason for buying a scope with tracking!) > I gave up trying after several firmware upgrades didn't correct the > problem. > Now I use Boshart's SatTrack (LXSAT) that tracks high objects OK, but I'm > not yet convinced about early-late sats. > > It would be nice though to be able to upload elsets into the Autostar, to > be > usable for a few days, and not having to expose the laptop to dew and > cold. > > /Björn > > ----- Original Message ----- >> >> Has anyone noticed how the Meade software does not track geosats? It >> point where it thinks the geosat is, based on the TLE, then moves East >> (and down) as time advances, as if there is a time term missing that >> should be correcting the position to stay where it it. ... > >> Second, does the error start when the calculations are first made or >> when the telescope is first pointed? Both of these problems impact not >> only tracking geosats but probably LEOs as well. > > > ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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