Topics

Mach2 and APCC last night


Terri Zittritsch
 
Edited

Finally a clear dark sky (not a hazy moon filled sky with clear spots) and I was able to use the mach2 from 8pm until around 2:30am (just before mooonrise).    The mount was a pure pleasure.  I was able to achieve .5 arc second guiding at 35 degrees above the southern horizon, over my house, and was able to keep it sub .8s at around 23 degrees above the horizon, about as low as I can go and don't typically get to image this low.      Later in the evening, or rather early in the morning, I went back to a higher target nearer the zenith and went to a sub .5 guiding.    I don't think I lost any frames all night due to guiding.    

The other thing I enjoyed was using APCC as the control center to make use of the meridian limits, which I created earlier with the interactive APCC meridian limits editor.   The process of creating the limits was easier than my interpretation from the manual.    The mount started both of my targets with weight-up, without any added thinking or setup on my part once the meridian limits were in place.   For me it's the east limits that I can make most use of to avoid an meridian flip.   More a time saver than anything else since it avoids an extra plate solve, focusing.   

Thought I'd provide a positive update since I originally said the results weren't as expected.

Also, on polar aligning, don't know what happened on my original testing, utilizing polemaster for polar alignment.  On subsequent nights I've used polemaster I've gotten pretty good results of an arc minute or better accuracy to the pole. 

Terri


Dean Jacobsen
 

On Mon, Mar 16, 2020 at 07:14 AM, Terri Zittritsch wrote:
The mount was a pure pleasure.  I was able to achieve .5 arc second tracking at 35 degrees above the southern horizon, over my house, and was able to keep it sub .8s at around 23 degrees above the horizon, about as low as I can go and don't typically get to image this low.
Good to hear that things are going good.

I expect that as you fine tune the parameters of the guiding software and you move to targets higher in the sky you will see substantially better guiding results.  My relatively low tech 900GTOCP3 consistently guides better than than 0.5" RMS in each axis over 4 or 5 hour runs as reported in the PHD2 logs.  0.5" RMS is a "bad" seeing night or I am low in the southern sky.  Other nights are much better. Some of my recent logs show <0.35" RMS for each axis over 4+ hour runs [interrupted for meridian flips].

The ability to get tighter guiding and faster settling times after dithers [required with my camera] is the reason I sprung for a new mount.
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Wayne Hixson
 

Excellent report Terri. We had a pretty clear night, but it was fairly breezy, still got better than 0.6" over 4 hours and a low target. I also use APCC meridian limits but in my case it's to cause a flip early. My "postage stamp" observatory on my eastern back deck is partially under my eaves of my house and the mount tracks under the eaves before the meridian. If I flip an hour or so before the meridian i can track over the eaves and get 3 extra hours. I use Voyager software to run everything and it handles centering, guider calibration and control, and focusing so I can sleep a bit - although I do get up just to check every once in a while! Really love the mount so far.

Wayne


Terri Zittritsch
 

Hi Dean, thanks..   It's a very quiet and confidence inspiring piece of equipment.. if that makes sense.     I have to admit that my knowledge of how to make guiding sing isn't consistent with how many years I've been doing this, but then I don't get to do this night night after night; I get to do this what seems like a hand full of nights a year.    I'm hoping to learn more, and maybe now with a piece of equipment that doesn't add too much color, I'll be able to focus on learning to tune the guiding parameters for the current sky conditions versus having to also account for the idiosyncrasies and imperfections of the mount.

T


Terri Zittritsch
 

On Mon, Mar 16, 2020 at 11:07 AM, Wayne Hixson wrote:
Excellent report Terri. We had a pretty clear night, but it was fairly breezy, still got better than 0.6" over 4 hours and a low target. I also use APCC meridian limits but in my case it's to cause a flip early. My "postage stamp" observatory on my eastern back deck is partially under my eaves of my house and the mount tracks under the eaves before the meridian. If I flip an hour or so before the meridian i can track over the eaves and get 3 extra hours. I use Voyager software to run everything and it handles centering, guider calibration and control, and focusing so I can sleep a bit - although I do get up just to check every once in a while! Really love the mount so far.
Hi Wayne, I had one of those two nights before, in fact very breezy.   So breezy it blew my computer shelter/crate right off the table while I was holding my laptop adjusting guide camera focus.    I didn't notice the mount with scope being too effected by the breeze (stowaway),  skies that night were not great and most of my shots have haze/halos around the bright stars, so probably going to toss them if the halos don't get rejected in processing.     Given how few clear nights we have i just hate to throw frames away!      That's pretty good to keep .6 arc seconds over 4 hours.   I was almost there on my second target last night but a moonrise stopped my progress as well as a need to get up for work today, even though we're working from home I still do a lot of video conferences and need to at least appear non-catatonic.  

My meridian flipping is the same as yours, an early flip so I don't get a flip during imaging (it doesn't matter all that much since I plate solve and pixinsight handles alignment and processing just fine), but it saves precious imaging time.   One of my targets flipped less than an hour early but the real test was my second target which flipped more than 2 hours early... no issues whatsoever.    So basically stayed the same orientation, weight on the west side the entire session, scope on the east side of the pier.     The object didn't pass the meridian until a little before 2am after starting at 11pm.

Terri





Wayne Hixson
 

Terri, I meant to ask if you use the refractive correction feature in PoleMaster?


 

I have used polemaster several times in an attempt to quantify differences with and without. I would call it more comparative than scientific

as near as i can tell it doesn't make a difference for me at my latitude (34deg north).

i think i would need polaris closer to the horizon for it to have an impact?

Brian

On Mon, Mar 16, 2020 at 12:06 PM Terri Zittritsch <theresamarie11@...> wrote:
Hi Wayne, I do.  But I've never done a test to determine just how much correction it actually does.    In other words, do a polar alignment with the correction on, and then check it again with correction turned off.   It might be an interesting experiment.


Terri



--
Brian 



Brian Valente


Terri Zittritsch
 

On Mon, Mar 16, 2020 at 02:44 PM, Wayne Hixson wrote:
Terri, I meant to ask if you use the refractive correction feature in PoleMaster?

 

 

Hi Wayne, yes, I usually have it on.   It might be interesting to do a test to see how much difference it makes.    In other words, do the polar alignment with the correction turned on, and then try it again with correction turned off.

After seeing that my alignment was so poor, I did a little reading on what the resolution is, and it's quite gross, so being a pixel off is big, maybe 30 arc seconds/pixel.    The other thing I notice is that looking at the alignment of the green box and red circle in precise align window, looks different than zooming in on the alignment marks on the main screen.    So this might be a source of error.  I've started using the cursor zoom feature and not looking at the precise align window and, at least anecdotally, this is getting me better alignment.

Terri


Wayne Hixson
 

That’s what I was thinking myself!


On Mar 16, 2020, at 12:06 PM, Terri Zittritsch <theresamarie11@...> wrote:

Hi Wayne, I do.  But I've never done a test to determine just how much correction it actually does.    In other words, do a polar alignment with the correction on, and then check it again with correction turned off.   It might be an interesting experiment.


Terri


Allen Ruckle
 

Terry, 
    I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error would have that much tracking error.

   Does the atmosphere produce that much error?  I share an observatory with a friend who has a 14.25" Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We  have gotten guiding with PHD-2 of .21 RA and .27 Dec  rms. using the Tik management feature.  The Observatory is located at the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

   I am waiting to be notified that the AP Mach2 I ordered last year.   I have been thinking it would have more accurate tracking than what I already have access to.   am I going to be disappointed?

aruckle


Ray Gralak
 

I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8
seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error
would have that much tracking error.

Does the atmosphere produce that much error? I share an observatory with a friend who has a 14.25"
Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We have gotten
guiding with PHD-2 of .21 RA and .27 Dec rms. using the Tik management feature. The Observatory is located at
the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.
Periodic error is completely corrected by the encoders but there are other sources of tracking error that must be minimized.

The level of tracking error will depend on the amount of uncorrected drift from polar alignment error, refraction, equipment flexure, tube currents, etc. Even with a good pointing model tracking quality is of course still dependent on the quality of local seeing and guiding algorithms.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Allen Ruckle
Sent: Monday, March 16, 2020 7:22 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Mach2 and APCC last night

Terry,
I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8
seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error
would have that much tracking error.

Does the atmosphere produce that much error? I share an observatory with a friend who has a 14.25"
Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We have gotten
guiding with PHD-2 of .21 RA and .27 Dec rms. using the Tik management feature. The Observatory is located at
the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

I am waiting to be notified that the AP Mach2 I ordered last year. I have been thinking it would have more
accurate tracking than what I already have access to. am I going to be disappointed?

aruckle


Terri Zittritsch
 

On Mon, Mar 16, 2020 at 10:22 PM, Allen Ruckle wrote:
Terry, 
    I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error would have that much tracking error.

   Does the atmosphere produce that much error?  I share an observatory with a friend who has a 14.25" Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We  have gotten guiding with PHD-2 of .21 RA and .27 Dec  rms. using the Tik management feature.  The Observatory is located at the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

   I am waiting to be notified that the AP Mach2 I ordered last year.   I have been thinking it would have more accurate tracking than what I already have access to.   am I going to be disappointed?
Allen, The atmosphere creates significant star movement in my less exotic locale (at 155M in Vermont under the jet stream).      And what I'm reporting is guiding (i'm actively guiding), not tracking.  So your .21 and .27 results in around .34 arc seconds total (root of sum of squares).   What I report you should compare to the .34.    I think almost all of what i see is the atmosphere and some due to my lack of precision in setting the right guiding parameters and some over-correction, that which then needs to be corrected.   Plus, I am a portable mount, and about the best polar alignment I get is around an arc minute, maybe a bit less, but this will result in some drift that needs correction.  

Since I've never owned another A-P mount, it's hard for me to compare.   Comparing to my old mount, it's significantly more controlled.. to where I feel I can start honing my guiding and A-P skills rather than continually account for idiosyncrasies of the mount.


Terri


 


Dean Jacobsen
 

On Tue, Mar 17, 2020 at 06:05 AM, Terri Zittritsch wrote:
Comparing to my old mount, it's significantly more controlled.. to where I feel I can start honing my guiding and A-P skills rather than continually account for idiosyncrasies of the mount.
That is why we pay the big bucks for a premium mount. :-)

Now you can stop worrying about the mount.  It fades into the background and reliably does its thing.
 
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Cheng-Yang Tan
 

Hi Terry,

FYI, although I don't have a Mach2, I have an AP1100 with absolute encoders. For me, the PHD2 rms guide errors are *strongly* dependent on seeing conditions. Last week on 06 March, when the seeing was terrible around here, even with encoders, the guiding was ~0.9 arcsec rms! But on Sunday night, 15 Mar, guiding was very good ~0.3 arc sec rms because the seeing was good. So although encoders help with getting rid of PE, don't expect miracles if seeing is bad.

YMMV

cytan

On Tuesday, March 17, 2020, 08:05:34 AM CDT, Terri Zittritsch <theresamarie11@...> wrote:


On Mon, Mar 16, 2020 at 10:22 PM, Allen Ruckle wrote:
Terry, 
    I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error would have that much tracking error.

   Does the atmosphere produce that much error?  I share an observatory with a friend who has a 14.25" Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We  have gotten guiding with PHD-2 of .21 RA and .27 Dec  rms. using the Tik management feature.  The Observatory is located at the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

   I am waiting to be notified that the AP Mach2 I ordered last year.   I have been thinking it would have more accurate tracking than what I already have access to.   am I going to be disappointed?
Allen, The atmosphere creates significant star movement in my less exotic locale (at 155M in Vermont under the jet stream).      And what I'm reporting is guiding (i'm actively guiding), not tracking.  So your .21 and .27 results in around .34 arc seconds total (root of sum of squares).   What I report you should compare to the .34.    I think almost all of what i see is the atmosphere and some due to my lack of precision in setting the right guiding parameters and some over-correction, that which then needs to be corrected.   Plus, I am a portable mount, and about the best polar alignment I get is around an arc minute, maybe a bit less, but this will result in some drift that needs correction.  

Since I've never owned another A-P mount, it's hard for me to compare.   Comparing to my old mount, it's significantly more controlled.. to where I feel I can start honing my guiding and A-P skills rather than continually account for idiosyncrasies of the mount.


Terri


 


Terri Zittritsch
 

On Tue, Mar 17, 2020 at 09:43 AM, Cheng-Yang Tan wrote:
Hi Terry,
 
FYI, although I don't have a Mach2, I have an AP1100 with absolute encoders. For me, the PHD2 rms guide errors are *strongly* dependent on seeing conditions. Last week on 06 March, when the seeing was terrible around here, even with encoders, the guiding was ~0.9 arcsec rms! But on Sunday night, 15 Mar, guiding was very good ~0.3 arc sec rms because the seeing was good. So although encoders help with getting rid of PE, don't expect miracles if seeing is bad.
 
YMMV
 
cytan
Cheng-Yang,  Thank you for agreeing with my feedback,  I am pretty pleased with the results on the Mach2 operation so far.. I think some others are questioning the results and I'm providing the best answers that I can.     But others, like yourself, with more experience can provide better answers.

Terri


Roland Christen
 


I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
I think people misunderstand what is a tracking error coming from a mount and an atmospheric seeing error caused by random motions of a star.

Certainly a star will bounce around more when it is low in the atmosphere, but that is NOT a tracking error. That is atmospheric motion which is easily enough measured simply by looking at the moment to moment position of a guide star in Declination when the guiding is turned off. As soon as you turn guiding off, the reported position of the guide star is exactly that of the atmospheric motion, and has zero to do with any king of tracking. That motion will also be present in the same amount on RA whether you are simply tracking or actively guiding. That amount is the floor below which you cannot go.

Rolando


-----Original Message-----
From: Allen Ruckle <aruckle@...>
To: main <main@ap-gto.groups.io>
Sent: Mon, Mar 16, 2020 9:22 pm
Subject: Re: [ap-gto] Mach2 and APCC last night

Terry, 
    I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error would have that much tracking error.

   Does the atmosphere produce that much error?  I share an observatory with a friend who has a 14.25" Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We  have gotten guiding with PHD-2 of .21 RA and .27 Dec  rms. using the Tik management feature.  The Observatory is located at the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

   I am waiting to be notified that the AP Mach2 I ordered last year.   I have been thinking it would have more accurate tracking than what I already have access to.   am I going to be disappointed?

aruckle


Roland Christen
 

I have a 1600 mount with a 1200mm fl 175EDF refractor in Hawaii. I just spent 2 weeks testing keypad software using this setup. The 1600 has encoders and is a sweet mount that is dead nuts accurate. On my first night the trade winds were blowing strong and my star excursions were up to +- 3 arc seconds from one exposure to the next. Overall tracking results were on the order of 1.2 to 1.5 arc sec rms. Even so, each 10 minute exposure had perfectly round stars of 7 arc sec FWHM.

When the trades stopped blowing a couple of nights later, the rms tracking values dropped to 0.25 and less. One night I had .09 rms tracking in a 20 minute exposure. Stars never moved more than 1/4 arc sec from the zero line.

Now, to make it even more interesting, I never used a guider for the entire 2 weeks that I was imaging. Rather I was testing the pure tracking ability of the encoder mount with a tracking model. I took hundreds of exposures with almost no rejects. I had only a couple of exposures with slight oval stars which were caused by 30mph wind gusts.

The encoders eliminate periodic error and make it possible to drive both axes at very precise custom rates that are created in a tracking model. The model I was testing happens to be the one we are adding to the new keypad software, but it applies equally to the APCC-APPM tracking model. Once you have modeled the sky, and you don't move the mount or scope, you can indeed eliminate guiding. I spent the early part of one night creating the tracking model and used it for 2 weeks. Worked perfectly every night.

If you don't have a permanent setup with good polar alignment, then guiding works fine too - as long as you have good parameters dialed in.

Rolando



-----Original Message-----
From: Cheng-Yang Tan via Groups.Io <cytan299@...>
To: main <main@ap-gto.groups.io>
Sent: Tue, Mar 17, 2020 8:43 am
Subject: Re: [ap-gto] Mach2 and APCC last night

Hi Terry,

FYI, although I don't have a Mach2, I have an AP1100 with absolute encoders. For me, the PHD2 rms guide errors are *strongly* dependent on seeing conditions. Last week on 06 March, when the seeing was terrible around here, even with encoders, the guiding was ~0.9 arcsec rms! But on Sunday night, 15 Mar, guiding was very good ~0.3 arc sec rms because the seeing was good. So although encoders help with getting rid of PE, don't expect miracles if seeing is bad.

YMMV

cytan

On Tuesday, March 17, 2020, 08:05:34 AM CDT, Terri Zittritsch <theresamarie11@...> wrote:


On Mon, Mar 16, 2020 at 10:22 PM, Allen Ruckle wrote:
Terry, 
    I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error would have that much tracking error.

   Does the atmosphere produce that much error?  I share an observatory with a friend who has a 14.25" Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We  have gotten guiding with PHD-2 of .21 RA and .27 Dec  rms. using the Tik management feature.  The Observatory is located at the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

   I am waiting to be notified that the AP Mach2 I ordered last year.   I have been thinking it would have more accurate tracking than what I already have access to.   am I going to be disappointed?
Allen, The atmosphere creates significant star movement in my less exotic locale (at 155M in Vermont under the jet stream).      And what I'm reporting is guiding (i'm actively guiding), not tracking.  So your .21 and .27 results in around .34 arc seconds total (root of sum of squares).   What I report you should compare to the .34.    I think almost all of what i see is the atmosphere and some due to my lack of precision in setting the right guiding parameters and some over-correction, that which then needs to be corrected.   Plus, I am a portable mount, and about the best polar alignment I get is around an arc minute, maybe a bit less, but this will result in some drift that needs correction.  

Since I've never owned another A-P mount, it's hard for me to compare.   Comparing to my old mount, it's significantly more controlled.. to where I feel I can start honing my guiding and A-P skills rather than continually account for idiosyncrasies of the mount.


Terri


 


Wayne Hixson
 

Really looking forward to trying that modeling out


On Mar 17, 2020, at 5:19 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I have a 1600 mount with a 1200mm fl 175EDF refractor in Hawaii. I just spent 2 weeks testing keypad software using this setup. The 1600 has encoders and is a sweet mount that is dead nuts accurate. On my first night the trade winds were blowing strong and my star excursions were up to +- 3 arc seconds from one exposure to the next. Overall tracking results were on the order of 1.2 to 1.5 arc sec rms. Even so, each 10 minute exposure had perfectly round stars of 7 arc sec FWHM.

When the trades stopped blowing a couple of nights later, the rms tracking values dropped to 0.25 and less. One night I had .09 rms tracking in a 20 minute exposure. Stars never moved more than 1/4 arc sec from the zero line.

Now, to make it even more interesting, I never used a guider for the entire 2 weeks that I was imaging. Rather I was testing the pure tracking ability of the encoder mount with a tracking model. I took hundreds of exposures with almost no rejects. I had only a couple of exposures with slight oval stars which were caused by 30mph wind gusts.

The encoders eliminate periodic error and make it possible to drive both axes at very precise custom rates that are created in a tracking model. The model I was testing happens to be the one we are adding to the new keypad software, but it applies equally to the APCC-APPM tracking model. Once you have modeled the sky, and you don't move the mount or scope, you can indeed eliminate guiding. I spent the early part of one night creating the tracking model and used it for 2 weeks. Worked perfectly every night.

If you don't have a permanent setup with good polar alignment, then guiding works fine too - as long as you have good parameters dialed in.

Rolando



-----Original Message-----
From: Cheng-Yang Tan via Groups.Io <cytan299@...>
To: main <main@ap-gto.groups.io>
Sent: Tue, Mar 17, 2020 8:43 am
Subject: Re: [ap-gto] Mach2 and APCC last night

Hi Terry,

FYI, although I don't have a Mach2, I have an AP1100 with absolute encoders. For me, the PHD2 rms guide errors are *strongly* dependent on seeing conditions. Last week on 06 March, when the seeing was terrible around here, even with encoders, the guiding was ~0.9 arcsec rms! But on Sunday night, 15 Mar, guiding was very good ~0.3 arc sec rms because the seeing was good. So although encoders help with getting rid of PE, don't expect miracles if seeing is bad.

YMMV

cytan

On Tuesday, March 17, 2020, 08:05:34 AM CDT, Terri Zittritsch <theresamarie11@...> wrote:


On Mon, Mar 16, 2020 at 10:22 PM, Allen Ruckle wrote:
Terry, 
    I am surprised to see the tracking you report as being .5 arc Sec. 35° above the Southern Horizon and .8 seconds of arc at 23° above the Horizon.
It would seem to me that if the Mach II mount with the encoders that almost completely eliminates all periodic error would have that much tracking error.

   Does the atmosphere produce that much error?  I share an observatory with a friend who has a 14.25" Newtonian f5.6, fork mounted with a 11" Byers gear on the RA and a SiTech II drive corrector. We  have gotten guiding with PHD-2 of .21 RA and .27 Dec  rms. using the Tik management feature.  The Observatory is located at the SDAA dark sky site in Tierra Del Sol about 60 miles east of San Diego at about 3600' elevation.

   I am waiting to be notified that the AP Mach2 I ordered last year.   I have been thinking it would have more accurate tracking than what I already have access to.   am I going to be disappointed?
Allen, The atmosphere creates significant star movement in my less exotic locale (at 155M in Vermont under the jet stream).      And what I'm reporting is guiding (i'm actively guiding), not tracking.  So your .21 and .27 results in around .34 arc seconds total (root of sum of squares).   What I report you should compare to the .34.    I think almost all of what i see is the atmosphere and some due to my lack of precision in setting the right guiding parameters and some over-correction, that which then needs to be corrected.   Plus, I am a portable mount, and about the best polar alignment I get is around an arc minute, maybe a bit less, but this will result in some drift that needs correction.  

Since I've never owned another A-P mount, it's hard for me to compare.   Comparing to my old mount, it's significantly more controlled.. to where I feel I can start honing my guiding and A-P skills rather than continually account for idiosyncrasies of the mount.


Terri


 


Dominique Durand
 

I'm also excited ...keypad routines ... then modeling with APPM.


Dean Jacobsen
 

On Tue, Mar 17, 2020 at 05:19 PM, uncarollo2 <chris1011@...> wrote:
Now, to make it even more interesting, I never used a guider for the entire 2 weeks that I was imaging. Rather I was testing the pure tracking ability of the encoder mount with a tracking model. I took hundreds of exposures with almost no rejects. I had only a couple of exposures with slight oval stars which were caused by 30mph wind gusts.
 
The encoders eliminate periodic error and make it possible to drive both axes at very precise custom rates that are created in a tracking model. The model I was testing happens to be the one we are adding to the new keypad software, but it applies equally to the APCC-APPM tracking model. Once you have modeled the sky, and you don't move the mount or scope, you can indeed eliminate guiding. I spent the early part of one night creating the tracking model and used it for 2 weeks. Worked perfectly every night.
 
If you don't have a permanent setup with good polar alignment, then guiding works fine too - as long as you have good parameters dialed in.
 
Roland,

How is the keypad upgrade project going?

This new keypad feature was something that tipped the balance in deciding whether to purchase a Mach2 and is definitely something that I will use.
 
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/