Guiding with 10 micron

[Ana Ta]

Hi,

10 micron probably does not need guiding with refractors, if proper star model is made. But, I am not sure whether it is applied to SCT scopes. So, I would like to be prepared for guiding with 10 micron.

Their manual tells: low aggressiveness, 0.1x sidereal and exposure >10 sec.

I would like to ask several questions.

1. If I use RA Agr:55; Hys: 15; MinMo 0.05; Dec Agr: 55; MinMo: 0.05

Scope Mx RA 2000; Mx DEC 1500, will it be OK?

2. What guiding algorithm to choose? What is setting for algorithm?

3. What sidereal speed will you recommend?

4. How to do exposure for 3-5 sec every 15-30 sec?

5. Could I use PHD2 RMS Error display without guiding?

Thanks a lot!

All the best!

AnaTa

[oliv...@gmail.com]

Hi AnaTa

I am not using the 10 micron, but the Planewave L500 which also has very precise encoders and direct drive. The telescope is a CDK 17 with about 2900mm FL. (In Chile)

What we found : there is some benefit which PHD2, especially on long exposures I.e. 10mn

RA and DEC aggressiveness should be set low: less than 0,35.

Exposure time should be 5 or 10s

Now concerning the 10micron, there is a little difference : it has worm shaft/gear which has some play resulting in non null backlash. So you would absolutely like to avoid guiding in both DEC North and South directions. Especially with long FL.

So a good trick to avoid that is to increase a little bit the DEC MnMo. Use approximately the double of RA MnMo (x1.5 to x2) until the DEC graph stays on one side only of the axis (a little bit above or under). 

The RA MnMo should be set at about 1/2 pixel of the imaging sampling.

So in order to answers more precisely to your question we would need to know the pixel size of both sensors and the FL of both telescope (or the same if you are using an OAG of course)

Clear skies

Olivier 

Le 9 mars 2023 à 08:00, Ana Ta <aaak...@gmail.com> a écrit :

Hi,

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/e1f99a0d-2404-46a6-99c8-7e4469e057fbn%40googlegroups.com.

[Ana Ta]

Hi Olivier,

Thanks for recommendations.

So, I will have RA and DEC aggressiveness 0.3; MinMo RA: 0.05 and DEC 0.1

I have several configurations, FL 800mm - 4.63um/pixel camera; FL1200mm - 4.63 um/pixel camera and FL 2000mm - 9 nm/pixel camera.

Yes, I use OAG. 

Please give me advise for algorithm for guiding as well.

Thanks again.

All the best!

Armen

[bw_m...@earthlink.net]

I think you’re going about this the wrong way.  No two mounts are alike, even mounts from the same vendor, and guide settings are very sensitive to image scale.  That’s why we have the new-profile-wizard in PHD2.  Just run it and follow its recommendations.  If your mount has high-precision encoders, check that box.  I am very skeptical of guiding at 0.1x sidereal, that sounds like a lowest-common-denominator guess from the mount manufacturer.  I would set the guide speed to 0.5x sidereal, then run the new-profile-wizard.  Get an alert-free calibration near Dec = 0 and then run the Guiding Assistant.  Follow the guiding assistant recommendations, especially for min-move values.  Leave everything else alone.  If you want to use a low-cadence approach to guiding, follow the instructions here:

 

https://openphdguiding.org/man-dev/Supplemental_Info.htm#Variable_delay_guiding

 

Note, you must be on the latest PHD2 dev release for this feature to be available.  Once you have things going, run some extended test guiding sessions on each side of the meridian – sessions of at least 15 minutes.  Then you can analyze the results (or we can) to see if anything else needs to be done.  All of this should be done when seeing conditions are at least average.  If you are planning on using the mount with different scopes, you need to create separate PHD2 profiles for each setup.  If you are going to use an SCT, you will almost certainly need to also use an OAG or the differential flexure will be a problem.

 

Good luck,

Bruce

--

[Ana Ta]

Hi Bruce,

I will follow your instructions and recommendations and let you know how it worked.

Thanks a lot!

All the bets!

Armen

[Ana Ta]

Hi Bruce,

I have followed your instructions: used wizard, calibrated and run guiding assistant. 

Worked fine. 5s guiding intervals. Total: 0.29" RMS.

On refractor, it worked perfect without guiding for 5 min. 

Many people build models with 50-100 stars. I did not do that, just did 5 star-model, still worked fine.

Let's see how it works with SCT. 

Thanks a lot!

Armen

On Thursday, March 9, 2023 at 12:37:46 PM UTC-6 bw_m...@earthlink.net wrote:

[bw_m...@earthlink.net]

That’s great, no real surprise with that mount.  You should get similar results with the SCT, just remember to build a new PHD2 profile for the new scope setup.

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/c6aa3adb-e4bd-4542-9333-7c8df8d5b822n%40googlegroups.com.