Re: EXOS-2 PMC Eight, displacement planets and the moon #EXOS2 #TECHNICAL #OpenGOTO #ExploreStars #alignment

Jerry Hubbell - Explore Scientific VP Engineering

On Thu, Nov 14, 2019 at 08:29 AM, Rodrigo Zelada wrote:
The punctual case with Saturn, which is currently in Sagittarius, one of the stars I used to align was Nunki, very close to Saturn's position. If I move the mount with the information of the catalog to Altair, it arrives well, (not centered by the effect of the cone error), if I move it to Shaula it also arrives relatively well, if I turn to M8 it also arrives well, but Saturn remains quite far (with Jupiter the same thing happens with Saturn), Saturn it is not seen in the telescope's visual field as in the other cases. 
Hi Rodrigo, sorry you are having this issue. it sounds like you have your southern hemisphere problem fixed again. I assume you are using the iPadOS version of ExploreStars 
To make sure the ephemeris program is working within ExploreStars I compared the current apparent coordinates for Saturn in Cartes du Ciel with those calculated in  the iPadOS version of ExploreStars

Saturn @ 1942 UTC 2019-11-14
CdC                RA: 19h11m26.60s DE:-22°18'27.7"
ExploreStars  RA: 19h11m51.00s DE::-22°17'57.0"

Jupiter @ 1947 UTC 2019-11-14
CdC                 RA: 17h43m07.55s DE:-23°12'44.9"
ExploreStars   RA: 17h43m09.00s DE:-23°12'48.0"

As you can see the ephemeris calculation in ExploreStars is better for Jupiter than Saturn, but even then the difference in position is equal to  6.1 arc-min in RA and 0.51 arc-min in DEC for a total difference of 6.12 arc-min. This is well within most eyepieces anyone would use when finding an object. The difference for Jupiter's coordinates is only 23 arc-sec or about 0.36 arc-minutes. So you would not see any difference in the pointing at Jupiter than a star nearby.

That only leaves some mechanical issue with your gear lash or flexure somewhere.  

Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at
1010 S. 48th Street
Springdale, AR 72762

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home

Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!

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