setting up celestron avx

[Magnus_e]

Hi.

There is forcasted clear skies in the end of next week, and i want to have a go at andromeda, but i need some help setting up my celestron avx.

I have had three attempts setting up the mount so far, and all have ended in objects beeng missed by +-1hour in RA.

My steps to set up is:

1. place the tripod and align it pointing north

2. level the tripod with a bubble leveler.

3. place the mount on the tripod and set the latitude

4. power on the mount and set time and location (collected from stellarium)

5. select quick align

6. slew to dec 0* and south, and find the nearest star to drift align (south timeangle collected fro stellarium)

    6-1 take 125 sec exposure (while slewing 60 sec +RA, then 60 -RA) to check alignment and correct if nesesarry

7. slew to dec 0* and straight west (the RA timeangle that intersects 0* dec at the horizon, collected from stellarum)

    7-1 take 125 sec exposure (while slewing 60 sec +RA, then 60 -RA) to check alignement and correct if nesesarry.

    7-2 if corrections was made repeat from step 6

8. Goto home position and turn mount on / off or select realign

9. select two star alignment and follow steps in hand controller.

So where does it start to go wrong?

Allready in step 6 it's easy to see that the scope is not pointing straight south.

In step 7 the scope points far below the horizon "My observing site is by the see "15-25m abow the wather line" and i can se wather reflection in the scope when i'm supposed to be amed at the horizon"

Steps 6-1 and 7-1 goes without a hitch, and as far as i know i'm polar aligned.

Step 9 i have tried both 2 star align and quick align, and i miss all objects by about 1h RA, maby more. Cannot even find andromeda, so i have only had a go at m42 so far. Don't really have a visual finderscope except a red dot sight in my camera's flash shoe, so it's not easy to find objects when the mount is missing so badly.

Other than the time and location that i get from stellarium, the mount need the time zone, and standard time / daylight savings time.

As i'm in Norway (UTC +1 hour) i select "Zone 1"

And as it is after 25 Oct and before 29 March i select "standard time"

I have watched a good deal of video tutorials on youtube about setting up a EQ mount, even specific ones for the AVX, and unless i'm missing some importent details, i should bee doing things right. But still missing objects.

All three times i have done this i have been werry carfull aligning the tripod and lathitude on the mount, so steps 6-1 and 7-1 have allways been spot on to begin with. Have never made any correections there. Last night i was imaging i also got a "star did not move enough" error in phd when it was calebrating.

Would greatly appreceate some tips on what i could change too fix this.

As it seems i'm allways missing by +-1h it might bee something wrong with the time setting, but i am in UTC+1 and it is standard time, so i really dont know?

[Scorpius]

I have the AVX and Celestron polar scope. I complete steps 1, 2 and 3 and then manually align on the NCP with the Alt/AZ adjustment knobs making sure the RA and Dec index marks are set dead on. Then I power on the mount and choose two star alignment. Once the two star alignment is complete, I add four calibration stars and this seems to put me close as gotos place objects very near the center of crosshairs in my reticle eyepiece and they generally stay centered for a good period of time. Of course guiding is pretty much a prerequisite for long exposure photography but it sounds like you're already using PHD which is what I do as well. If the pointing error is consistent in all parts of the sky, it could be the time zone, time entered, date entered or GPS coordinates or if you're relying on the mount's factory applied latitude scale that could be the cause since they're known to be notoriously inaccurate. Other than that not sure what the problem might be although the AVX will retain the last GPS coordinates you entered so if you're in a substantially different location since the last time you input coordinates, that could be the problem. I'm not familiar with the process you describe in steps 6 & 7 and don't understand why those steps would be necessary to align the AVX.

Even if you don't have a polar scope, I've read that a good method for aligning on Polaris is to remove the polar axis covers and visually align Polaris in the center of the opening by using the manual adjustment knobs (The RA/Dec index marks should be set when doing this) Then after lining up on Polaris the hand control routine should compensate for most of the remaining polar alignment error.

Hope you get it sorted out as I've found the AVX to be a good mount and I've been pleased with its performance so far even though weather's been so bad here in the eastern US that I haven't had a chance to do any imaging for over well over a month...

[Gazabone]

Really hacked off with my AVX, even when using star sense. I can get way greater accuracy with a SW EQ3-2 using setting circles. Feeling heavily inclined to "upgrade" the AVX for a NEQ6 (non-GoTo)!

[Magnus_e]

Scorpius: Steps 6-7 is to polar align using Drift Align by Robert Vice "DARV". I do not have a polar scope and have been using the factory latitude marks as an initial setup.

DARV is supposed to do the polaralignment using the camera and a method called drift alignment in stead of using a polar scope. I do belive i'm doing it correctly, but as i'm always spot on without needing to adjust i might bee doing something wrong. I don't have any view to in the north direction, so i don't tink i'll be able to use the "non scope" polaralignment that you mention.

The pointing error seem to be consistent in all parts of the sky, and is terrible! If i select m42 i have to slew in RA for +15 sec with the motor speed at the default when selecting a object, witch i tink is motorspeed 8! When i have done that i'm pointing between orions belt and m42 and have to slew DEC a short ammount to find the nebula. As this error is consistent i am werry far of all alignment and callibratoin stars, so i'm not shure if i have ever found the right ones.

I don't have a battery for my mount yet, so all my sessions have been on the same exact spot. I have tried to slew directly to m42 after setting time and place and the pointing error is about the same. Quick align of course is not werry accurate, but it should bee in more or less the right direction?

Also something confusig was that when i used GoTo to m42 "and missed badly", then slewed manually to m42. I shot some frames and stellarium told me orion nebula crossed the meridian. As i wanted to set up for the rest of the shot i wanted to do the meridan flip. The mount was set to image 20* past the meridian "default", so i sat it to "prefere west" and selected m42, and it did the flip. The confusing part is that according to where the mount clamed m42 was, it would not cross the meridian for atleast one hour. Does the west setting in the meridian menu allow you to do the meridian flip before the object have crossed?

It's a bit confusing, but i really think it's a time or location thing. Both i get from stellarium on my phone with gps enabeled, and i do remember to push the set time to now button in stellarium for android

[Magnus_e]

//edit

I am using guiding and PHD and do get 10min subs without obious tracking errors

[Leveye]

Don't forget when initially aligning the mount to point it to your true north or south position and not simply your magnetic one. That right there can throw you off by over 15 degrees.

[PeterCPC]

I set mine up using Skysync and ASPA and can get 10 min subs with PHD or at least 4 mins unguided. GOTO is very accurate.

Peter

[Magnus_e]

That might be the issue. What Leveye says. I'm using a phone app compass and pointing the tripod straight north when initially aligning.

I did bellive that DARV should let me know if i was off in polar alignment so i could correct, but as i'm about 15-20* off target then this seams like a likely culprit

What is the best way of finding true north? Is there an app or a teknique to find it ?

[PeterCPC]

I just point North - ASPA will give you the required adjustments.

Peter

[Magnus_e]

Thanks for the tip Peter. My mount only came with a quick guide in english. The manual was in germna, so i have not used all the funktions. Found this link after seing your tip, and it looks straigth forward http://www.celestron.com/university/astroimaging/all-star-polar-alignment

[PeterCPC]

Just remember that once you have done ASPA, do an alignment check. You may have to do another ASPA but it will be much quicker as you will be much closer after the first ASPA.

Peter

[Magnus_e]

Thanks for the help so far

Haven't got to test the new knowlege yet, as it's werry cloudy at the time beeng.

But two more questions came to mind, that i cannot figure out.

1. What kind of batteries are you using? I have been looking at a 55ah car battery. I did some crude math and figured i would get slightly under 10h on a charge.

But when i was looking at the power banks sold at the retailer one of them was labeled 15ah. I have heard tose batteries only last a year or so, but it got me thinking that the 55ah is seareously overkill.

I live in an apartment in a light polluted part of time, so at the time beeing i'm visiting my parrents about a hour out of town when i want to use my scope. A good battery would make things easyer

2. I want to be able to use the mount and my autoguider with my newly modded canon eos and standard lens. Does anyone have any good ways of doing that?

I was thinking of just buing a dovetail and a kamera ballhead. If i just screw the ballhead on one end of the dovetail and the autoguider on the other end, would that work? I think the avx has a 90* offset for side by side mounting in the menu?

[PeterCPC]

Power wise I either use a mains adapter or a Powertank. Lots of people use leisure batteries so that should be ok.

Peter

[Magnus_e]

Thanks for the reply Peter.

Think you just saved me some $$$

I'll probably go for the power bank solution