Topics

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


Rodrigo Zelada
 

Hi, thanks for your response, I had not considered the cone error.

But even so I have a doubt, that I cannot solve it considering the cone error, which although it affects the position in different areas of the celestial sphere.

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. 

I would expect to see the same displacement of the stars in this area of the celestial sphere when I point to Saturn or Jupiter, but it is much more and they are out of the telescope's visual field.

 I correct the cone error of my telescope assembly and do the same exercise.

Thank

Rodrigo

El mar., 12 nov. 2019 a las 20:00, Wes Mcdonald (<wesmcd6@...>) escribió:
Rodrigo

I have been modeling the alignment procedure and have arrived at several conclusions.  

1.  Irregularities can occur in go-to based upon errors in your Dec home position.  Similarly errors in cone angle will persist even after three star alignments.  Thus you need to assure these are minimized before you perform the alignment.  I note the cone angle is correctly compensated for in the three stars used in the alignment but not across the sky.

2.  Your precision of centering during the alignment can affect your result.  So use a cross hair eyepiece and get close during alignment.

3.  When you sync on an object you bake in the Az El rotational error imposed by home error and measurement error.  These errors get rotated around the sky and affect other objects.

4.  The residual errors discussed above affect some objects more than others depending upon where they are in the celestrial sphere.  Thus you can have good results in one object and poor in another.  

My simulations suggest that the cone error and Dec home.error are to blame for the things you are seeing.  It suggests you have Dec home error likely on the order of 1 or 2 degrees.  You can eliminate Dec home error using the procedure I posted in the mounts subgroup in the files section.  Do this before you start after you have.set up and leveled the mount .  It only takes a a few minutes.   As for cone error you should eliminate it using the method posted by Jerry with a link to the Astronomy Shed YouTube channel.  

I don't believe there is anything incorrect with the planet vs DSO pointing.  While possible, the results you are seeing are far more likely due to one or both of Dec home or  cone angle.

Wes



--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired



--

Rodrigo Zelada Bacigalupo

Gerente General
North Optics Instrumentos Científicos y Ópticos
Asesoría y Venta de equipamiento para observación astronómica y astrofotografía
+56 9 9321 6519
Cristóbal Colón #352 OF. 514, La Serena IV Región de Coquimbo





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 explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

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
Mounts
: 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!


Rodrigo Zelada
 

Hi Jerry, thanks for your reply.  I am using the Android APP.  

The difference I see is much greater.  First I will make the correction of the error cone  and I will make the observation again.

Rodrigo 

El El jue, 14 de nov. de 2019 a las 16:57, Jerry Hubbell - Explore Scientific VP Engineering <jrh@...> escribió:
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 explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

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
Mounts
: 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!

--
Rodrigo Zelada B.
North Optics
Equipamiento para observación astronómica.
+56 9 9321 6519 / + 56 9 9624 0750
Cristóbal Colón # 352 oficina 514, La Serena
IV Región de Coquimbo.
www.northoptics.cl


Jerry Hubbell - Explore Scientific VP Engineering
 

On Thu, Nov 14, 2019 at 04:01 PM, Rodrigo Zelada wrote:
I am using the Android APP.  

Hi will do the same ephemeris check on the Android, it should be pretty much the same because the ephemeris code is identical across the platforms.

Thanks
 
--
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

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
Mounts
: 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!