Wasted night last night

[gbcarync]

The forecast was great for last night and the moon wasn't gonna set until nearly 1am, I set the scope up and shot a bunch of darks planning on doing a couple hours of 5 minute, 400 ISO exposures of the Veil nebula. I polar aligned and then shut everything down to come inside to charge my DSLR battery and rest until 12:30 (set my alarm).

I apparently set my alarm to 1:30AM by mistake (Doh!). So by the time I came out, Cygnus was almost directly overhead and heading for my oak tree.

I did a 1-star alignment on Altair so I wouldn't have to lay on my back like I would to see Vega or Deneb in the finder and then did a GOTO to NGC 6960.

That was when I hit a brick wall. I could not get my guiding to work. PHD RA calibration would fail after 61 steps saying the star did not move enough. I thought maybe my alignment was off so I polar aligned again, repeated my 1-star alignment and had the same result. My tracking was great. 60 second subs showed very little trailing and 30 second subs looked great. But not being able to guide, 5 minute subs were out of the question.

Google found some suggested solutions: Make sure the ST-4 cable was securely connected between the camera and the mount, making sure the correct mount was selected in PHD, increasing the calibration step distance. None of that helped.

I ended up shooting about 10 30 second subs of M15 just for the heck of it and then called it an night (morning) after 3PM.

Subsequent research leads me to believe I had a communication problem between the camera in the mount. I can experiment with this in daylight and try "manual guiding" and see if the mount responds to commands. Maybe the ST-4 cable got messed up when I wrapped around the mount post (I may have wound it too tight).

At any rate, the clear skies last night were wasted on me but I feel like I'm learning a lot.

[Phil Leigh]

Some suggestions:
1) increase calibration step time up to 2,000ms
2) make sure you have selected a star not a hot pixel in the guide cam (easily done!)
3) check the backlash on the mount - if it is too high, the calibration pulse may not physically move the mount enough
4) use PHD pulse guiding instead of ST-4 (needs EQASCOM/EQMOD) - I use this exclusively now, having started exactly as you are. I just find it works better with my mount (which is similar to yours)

[KeithBC]

Sorry to point out the obvious, but sometimes that's where the problem lies: are you sure that both clutches were locked?

[kszakonyi]

Ditto to what others have said with an addition that I actually had to step my calibration interval to around 2500 and then my guider worked.

[gbcarync]

Thanks for all the replies. I am pretty sure the clutches were locked. When the calibration failed, I thought that perhaps something was wrong with my alignment so I took the scope off and checked my polar alignment and then put everything back on and then redid my alignment.

I am going to try increasing the calibration interval and in manual tracking mode make sure the mount is receiving commands. If not, I might try another cable and if still having issues look for software configuration issues.

This entire setup worked perfect my two previous outings so I am hoping it is user error

[MidnightSun]

A loose screw can cause alotof headaches.....I know.....check everything.

[AstroChuck]

I just got a Sirius mount and have had the same problems. In "setup" there is a field called auto guide speed. Mine is .5x by default. This has caused me havoc. Ran to 50 something and I shut it down(I too use the 50mm guidescope and PhD) I changed the autoguide speed to 1.0x it it calibrates quicker @ 30. Seems to work ok. Even though I change it, it will default to .5x. If I forget the next night Phd will run to 60+ and never "guide"