Experiments in Guiding (PHD, Travelscope 70 & Firefly MV

[SnakeyJ]

Just a quick post on this - I've been experimenting with a first guiding solution, based on; Celestron Travelscope 70 guide scope, piggbacked on SW Exp 200P on my HEQ5 Pro mount (3 counterweights!). The all up weight is probably pushing this past sensible limits with standard finder, telrad, filter wheel, SW Coma Corrector and dew heaters. Although I have a perfectly good guide cam (QHY5L-IIM), I've been using this to do the imaging and dusted off the old Pt Grey Firefly MV Mono (using Ludovic Pollet's ascom driver).

I've used it over a couple of nights this week and it does actually work quite well, though fair to say that the sensitivity of the Firefly is the limiting factor and I am not sure it would work well with a smaller finder guider setup. For anyone wanting to use the firefly the ascom driver is compiled around version 2.3.3.18 of the FlyCap2 x86 - although the source is available I think it would need some tweaks to work with later versions. However, it does run happilly on my Windows 7 x64 laptop.

Unfortunately the full moon and quite windy conditions are not most suitable for imaging, though a couple of images are attached as an example/proof:

Half of NGC 884 - the double cluster (limited FOV with the QHY5L-II

M13

Both images are only 30 sec subs, which I could achieve unguided - but more as a representative sample. I shall try some longer exposures once the conditions improve. I was guiding on both RA & DEC axes, which may not be the optimum setup but did keep the targets nicely framed for the duration of the runs.

I have run the PHD logs through PECPrep, which provides some pretty graphs though I only have a tenuous grasp of what this means.

RA Residual PE

DEC Residual PE

Now it seems I can load these curves in to EQAscom to smooth out these errors and improve guiding. Though I assume that this data is only useful until I unlock DEC or RA clutches and move the mount - is this correct. I understand there is an offset/phase function, but not sure if you need encoders to accurately use this.

The other thing I wondered if is it possible to shorten the calibration

I'll look out some more tutorials to see if there are any tips or tricks, but if anyone spots anything glaring I'm all ears

[SnakeyJ]

Hot from 12dstring site - the 70 x 400mm guide scope, coupled with the MT9V022 sensor's 752 x 480 x 6um pixels gives the following FOV and resolution:

F ratio: Focal Length: Field of view: Resolution:

f5.71 400mm 38.78' x 24.75' 3.09 "/pixel

Oh for a WYSIWYG editor that does tables

[Keener_7]

Actually, I was thinking of trying this. Had plans to mount my travel scope on my 8inch newt to give guiding a try( just to see how it all worked). The problem I have is that the only camera I have is a xbox webcam. Do you think it would work as a guide cam? I was going to give it a shot tonight but clouds and rain rolled in a couple of hours ago and it looks like they are staying.

[SnakeyJ]

Actually, I was thinking of trying this. Had plans to mount my travel scope on my 8inch newt to give guiding a try( just to see how it all worked). The problem I have is that the only camera I have is a xbox webcam. Do you think it would work as a guide cam? I was going to give it a shot tonight but clouds and rain rolled in a couple of hours ago and it looks like they are staying.

I did have a quick try with the xbox live webcam, though it's not as sensitive as the firefly. It will work, but probably only on brighter stars. I shall have another go and see if can quantify this more usefully, but the full moon has been hampering the experiments somewhat.