Andrew INT

Hello and welcome to the forum. They really are a helpful lot here - given me loads of good advice and help over the years!

Ooh, has to be Orion for me!

Hello and welcome to the forum. They really are a helpful lot here - given me loads of good advice and help over the years!

Hello and welcome to the forum. They really are a helpful lot here - given me loads of good advice and help over the years!

2 hours ago, michael8554 said:

Hi Andrew

I reread the PHD2 instructions and you're correct, 1.2 is the preset Min Star HFD - my bad.

From the GuideLog:

The Calibration Step Size on your guiding run was 900mS, not 5000ms  - is 5000ms something you set in EQMOD ?

Your HFD from the guidecam is 4.17pixels, you might be able to improve that.

 A Min Star HFD setting of 3 is too close to 4.17, so may be rejecting good stars, back that setting off to 2.

Your guidestar SNR is only about 7 which seems low to me, but depending on the camera can be as low as 20, and up to 800 or more.

You have Star Max Detection ticked, this might be rejecting good stars too.

RA Error is 1.28arcsecs, and is quite choppy, so try Aggression = 80% or lower to smooth that out, changes of only 1 or 2 % are too small.

Give each change time to settle.

Or try the PHD2 PPEC Algorithm for RA guiding.

PA is good, but Dec is still swinging around the axis due to Backlash, and taking 20 seconds to correct.

If you do a Guide Assistant run on Target, that will give you Min Move settings, and a Dec Backlash Compensation setting, which you have switched off.

And you should slightly unbalance Dec to stop it wobbling.

Michael

 

Hi Michael,

I had changed the calibration steps to 5000ms in PHD2 - I guess I must not have hit ok! The calibration step calculator suggests 1100ms, so I will try that too.

I shall make all your recommended tweaks on the next clear night, as well as offsetting the balance a little in Dec, and running the guide assistant. Not sure where to turn the dec backlash compensation on - I'll have a look for it!

Thanks once again for your invaluable assistance

1 hour ago, michael8554 said:

Not sure what you mean by minimum star reference size  - do you mean Minimum Star HFD ?

If a Hot Pixel = 1, so a setting of 2 or 3 would work, not sure why you have fractions of pixels in the setting.

The Pulse Duration of 5000 I suggested was for Manual Guiding, so that won't have made any change to normal guiding ?

Although your guiding is looking good it would be worthwhile posting the PHD2 GuideLog.

Michael

 

Hi Michael,

Yes, I meant the minimum star HFD. This value was set at 1.2 (I think that was a default setting).   I increased the value using the arrows - which incremented in 0.5. I've since re-set this to 3.0

Using the calibration calculator, PHD2 was setting the calibration set at 1100ms. This still resulted in the RA error. However, setting this to 5000ms resulted in calibration. As requested. I've attached the log. Thanks once again for looking!

Andrew

PHD2_GuideLog_2021-06-12_112421.txt

A big thankyou to Michael and Martin! 

I amended the minimum star reference size from 1.3 pixels to 2.7 and also increased the pulsing duration to 5000. I was then able to calibrate at the first attempt! Its not the smoothest of guides, but my mount is working beyond it's imaging payload anyway.  I'm sure I can work at smoothing it out a bit more over the next few clear nights

Thanks once again folks!

Andrew

Guiding Graph 13 06 21.bmp

Hi Budgie1,

Yes, I have a dark library. Also tried guiding on different stars (auto and manually selected).

I'll check the star reference size though, I can't remember what that had been set to - thanks.

Thanks Michael, I'll try pulsing at 5000 tonight. In the past I've guided on-camera without any real problems, although calibration did still take 61 steps.

Do you think I could have removed too much backlash? That said, the mount still tracks and slews without any binding sound - and I rotated a full 360 degrees in RA and Dec. Hmm.

If it helps, here is also a screenshot of my EQmod settings - thanks once again!

Hi Guys,

For the last few weeks I’ve been trying to sort out a PDH2 failure to calibrate issue I’m getting. I’ve guided in the past, but I’m far from knowledgeable regarding the PHD2 settings. My problem is this: Last month, I tried a re-calibration, and all I was getting was ‘calibration failure, RA star did not move enough.’

I was aware that my HEQ5 mount had some bad backlash, so I spent a few hours removing that. Still got the same error. I had been using a usb to serial to RJ lead combination. I was never particularly happy with this (I had to bind the two leads together with electrical tape to stop them detaching). So, I now have an EQDir cable; much better…but I still can’t calibrate in PHD2. I can control the mount fine through Stellarium and the mount tracks ok.

I think the issue must be within the PHD2 setting or possibly the EQMod tracking rate – I’ve tried 0.1 to 0.9 (and used the calibration step calculator each time).

I’m guiding through an Evoguide scope (FL 242mm) and an ASI 120MM mini guide camera (3.75u).

I think the error probably sits with me rather than the hardware. Is anyone able to offer any advice please? I’ve added last night’s PHD2 log – I tried a number of settings, but no joy!

Any help would be fantastic!

Andrew   

PHD2_GuideLog_2021-06-10_225310.txt

4 minutes ago, Astro Noodles said:

Thanks Andrew -I'll get it for my Kindle.

Thank you ever so much  Astro Noodles. Hope you enjoy it.

Hi all,

Hope this post is ok (please remove if not).

A few months ago I wrote a psychological sci-fi novel set in the 1940's about an astronomer. I've kept the astro side of things as accurate as possible and thought some people here may enjoy reading it.

Although you can buy it in paperback or on Kindle, if you have kindle unlimited it is currently free to download.

It was very much a labour of love. I promised myself that once I gained my astrophysics degree I would write a book. It took a few years of work to complete. Any help in getting it noticed on Amazon would be greatly appreciated!

Thanks once again, 

Andrew

The Starlight Demon

That's one giant...leap...for mankind!

Thanks for the info Budgie1, that's really helpful...and reassuring! I had looked at that exact cable, and another one for about £40. I'll order the one you have. Did yours come with a PSU?

I'll also order a powered usb hub (thanks for the advice Alan). I have a £100 budget so should just about do it

Thanks Alan for clarifying that! I was also going to buy an additional power supply for the cable. My current usb hub isn't powered- do you think that would still be okay?

Thanks Clarkey, that's good to hear! I know that a raspberry pi would probably be a better solution, but I'm really not very IT literate. Extension cables I can deal with!

Cheers

Hi,

After much a do with putting up with British weather, I have decided to civilise astronomy by moving my laptop indoors.

I'm looking to purchase a 15m active 3.0 USB  cable in order to run four devices through a USB hub (imaging camera, guide camera, filter wheel and ASCOM cable). 

My question is this: I've read (through an Amazon customer review) that each extension chipset in the cable counts as one device...and that a USB port is limited to five devices. Is anyone able to confirm this please? Does anybody use a 15m extension cable with one or more chipsets along it? I don't want to spend £60 or so on a cable that can't run four devices.

Thanks for any advice folks!

Hi Steve,

I have focal length (1003mm for my 8" Newtonian) and 2.9 microns for my pixel size saved in the tab. The field of view is  not particularly big (about 19x10 arc mins). My laptop only has an i3 processor, maybe that could be the problem?

Andrew

At the moment, I'm not connected to the mount or camera - just uploading an old image file and blind plate solving.

I am trying to plate solve for the first time but am not having much (any) success yet. Hopefully someone here will be able to show me the errors of my ways. I intend to use ASPS in partnership with Sharpcap Pro, however, at the moment, I cant even get ASPS to solve a single image.

My FOV is 19.3 x 10.9 arcmins and I have download the relevant index 4202, 4203, 4204, 4205 (and 4206).  In the plate solver setting I have my FL (1003mm) and pixel size (2.9um) entered.

When I select a file to solve however,  the 'work in progress' counter just ticks away (I tend to abort it after an hour!!!)

I have uploaded the same image files onto Astrometry net and they have been solved without issue (and also confirm the FOV). I must be doing something wrong!

Cheers,

Andrew

Oh, I see. Thanks Seelive. I was thinking that LST was my actual local time. So, I can use the LST to judge what objects are crossing the meridian based on their R.A. (I think)

Thanks.

My longitude is 0 7' 4.6" E so LST is going to be very close to UCT. Laptop clock shows 17:09, Stellarium clock shows 17:09 (not sure where calculated LST would be displayed), but EQMOD is still 8+ hours ahead.

4 minutes ago, Merlin66 said:

Andrew,

I use Cartes du Ciel, but the LST in EQMod should match that shown in your planetarium package. Have you checked??

Hi. Yes, the time in Stellarium matches the laptop clock.

Hi,

After (finally) going down the route of autoguiding, I have managed to control the mount via Stellarium, image through Sharpcap pro and guide (reasonably), through PHD2.

However, EQMOD reports the LST as about eight hours out! I have the correct coordinates entered, which also match Stellarium. Not sure how to resolve this.

I'm running (the HEQ5 pro) through the hand controller in PC mode.

Any help, greatly received!

Thanks,

Andrew

Thanks, I want to go down the autofocus path at some point. The baader clear filter is supposed to match my baader narrow band, i.e parfocal (ish).

I'll have a rethink of what I use- thanks for the advice!