Jump to content

1912116577_Solarchallenge2022banner.jpg.913a200cf105ddeae9f37765cb1d0c73.jpg

Phd guiding problem


Recommended Posts

Hi guys I'm sure this has been asked before I've searched bit cant really find anything .

I'm trying to guide using phd and also phd2 but not having much luck .

I've set up my guidescope and I'm using a Samsung scb 2000 camera as a guide camera.

Once connected it shows up stars etc and allows me to pick a star and it goes into calibration and it sometimes calibrates Ok and starts to guide but then looses  the star snd gives an error something about the mount and guiding maybe ineffective. 

All connections are good and cables are sound is this something in the settings or is my set up not capable of guiding .

As always any information will be gratefully received. 

Thanks in advance best regards Barrie 

Link to comment
Share on other sites

5 hours ago, barrie greenwood said:

I'm using pulse and it was pointing at Vega

Ok, next clear skies(????) Point it south, Click on the drift tool, that brings up where you're pointing.. slew the scope so you have 0 Dec and as close to 0 in az as you can, but pay attention to what side the scope is on.. if it's on the east side of pier then have a -  .....  then calibrate..

Edited by newbie alert
Added info
Link to comment
Share on other sites

3 hours ago, newbie alert said:

Ok, next clear skies(????) Point it south, Click on the drift tool, that brings up where you're pointing.. slew the scope so you have 0 Dec and as close to 0 in az as you can, but pay attention to what side the scope is on.. if it's on the east side of pier then have a -  .....  then calibrate..

Ok I'm lost here point the scope south yeah? if that's the case then 0 dec would be east .

Do u have a step by step for idiots I don't need any real detail just an abc ish .

Thanks newbie

Link to comment
Share on other sites

If you point the scope south, the counterweight bar on an eq mount will point due east or west. 0 dec means that you are looking at the celestial equator (which is earth’s equator extended). From the horizon, look as many degrees up as 90 - your observing’s location latitude. For me at 60 deg latitude that would be 90-60=30 deg up. When you do the calibration, you shouldn’t point lower than 40 degrees though, so you avoid atmospheric disturbances.

Link to comment
Share on other sites

Why not calibrate close to the pole? Just think of the size of the circle described by a star up there during one sidereal day: it's tiny, meaning the star hardly moves in a day, let alone in the time taken to calibrate. That means that the calibration can obtain very little information about the tracking error since it is compressed onto a tiny circle. If you calibrate near the equator that circle opens up into what is approaching a straight line from the mount's point of view so it has much better information about the effects of tracking error.

If you wanted to see if the stars appear to move with naked eye and chose Polaris, you might think they didn't. If you chose Betelgeuse you'd soon see that they did.

Olly

Link to comment
Share on other sites

7 hours ago, barrie greenwood said:

Ok I'm lost here point the scope south yeah? if that's the case then 0 dec would be east .

Do u have a step by step for idiots I don't need any real detail just an abc ish .

Thanks 

In simple terms, point it south and about  45 degrees... click on the drift tool.. this brings up a box with the coordinates of where it's pointing...  slew the scope and get the DEC on 0, and as said previously,  depending on which side of pier the scope is, depends what side of the meridian you want to be + or minus.. minus if the scope is on the east side, but fairly close to zero... plus if it's on the west..then calibrate

If you calibrated on Vega I'm supprised it didn't flag up saying that it's too far from the equator 

If you theoretically shoved a pencil through both poles . At night you can see the tip of the pencil pointing more less at polaris , you cant see the pencil sticking out of the south pole as its through the earth...and the high side of the 23 degree tilt will be the equator..  hope this doesn't confuse even more, it's not intended

Link to comment
Share on other sites

1 hour ago, barrie greenwood said:

Drift tool?? 

I set it at that just to see if understood you guys correctly. 

So I calibrate it around that area and once calibration is done I can then pick an object slew to it pick a guide star and guide I'm I correct .

Regards Barrie 

Drift tool in phd.. under tools 

In the advanced settings there's a tick box to check to maintain calibration,  so once done you won't need to callibrate everytime 

Link to comment
Share on other sites

Hi Barrie

From your GuideLog:

Your exposures are only 20mS, is that as slow as the Samsung scb 2000 will go ? Most guiding is done at 2 to 4 seconds exposure.

As a result there were many "Star Lost" messages, particularly during Calibration.

The mount driver is reporting this guiderate setting:

RA Guide Speed = 13.5 a-s/s, Dec Guide Speed = 13.5 a-s/s,

But the Calibration has calculated the guide rates as only:

 RA = 3.4"/s , Dec = 4.1"/s;

This suggests you have the ASCOM PulseGuide Setting in EQMOD too low.

You say "I've set up my guidescope",  and the focal length is entered as 1000mm, is that correct ? 

Or are you using an Off-Axis -Guider ?

So the guide image scale is only 1.3arcsecs/pixel, a 300mm guidescope would show more stars, and give 4.33arcsec/pixel.

Read this, particularly clearing backlash before Cal:

https://openphdguiding.org/phd2-best-practices/

Michael

Edited by michael8554
Link to comment
Share on other sites

Hi guys .

Ok after reading the posts on this there was a lot to look into however in between gusts tonight it's guiding to a reasonable amount the high wind is killing it but ive managed to get it to play along .

There are lots of settings to play about with and I had a real issue with an error reporting its wasn't moving the Dec enough where is the setting that I can change that with. 

Also no I'm an idiot the guide isn't 1000mm that's my main scope the guide is 60mm the camera is z lot better on 1 sec exposure as well .

Regards Baz 

Link to comment
Share on other sites

Are you drifting as your DEC looks like it's drifting upwards of the trend and your RA is going opposite  ,so balance and PA could need to be tightened up

What mount are you using,  and what's the rest of the setup?

Just before you calibrate on some mounts its advised to take the slack out of the DEC gear... once you have calibrated run the guide assistant and apply the  recommended settings

1 sec loop might be too short.. it's ok in bad seeing to keep the exposures short, but if you're losing the guide star because of conditions then maybe it's not that great to be imaging anyway

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.