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Hi, all:

Sometimes the NCP is not aligned very very accurately. For a target, especially a fainter one, perhaps it's 5~7 magnitude, in the FOV of guiding camera to LHIRES III, how to identify which is the one I am going to observe?

And on such situation, maybe telescope can not slew correctly to the target and position it onto the slit accurately, then how to handle this boring problem? Do you have some good methods and advice?

Dong . Li

I think a good finderscope aligned with LHIRESIII would be simplest. At the magnitudes available to the LHIRES III it would not need to be large and if you wanted to use it with a webcam that should also be ok. Then it's down to finder charts etc.

Regards Andrew

Yes that is what I use. I use the standard finder with the C11 (50mm?) with a webcam directly mounted behind the eyepiece. This is OK to about mag 6. For fainter targets, I use the finder to locate a nearby bright star and use that to sync the Goto (EQ6/EQmod/Cartes du Ciel) A slew from this star to the target is usually accurate enough to land it in the LHIRES field

Cheers
Robin

Thank you ~~ Andrew and Robin!

I begin to become clearer by reading your reply,Robin. I have the same finder wtih my C11 [9x50], and I additionally put another short telescope [70x350 = 70mm diameter+ 350mmfocal length] piggybacking on C11, yes I am to connect a webcam with it. Here in Tianjin, seeing & transparency are not very good usually in summer, the LM is about 3 with naked eyes; but in other 3 seasons, my location is very good, many sunny nights with good seeing, LM can be about 4. Especially it is very dry, is this a good situation for taking spectrum?

Today I went to the office of QHYCCD in Beijing to ask some questions face to face. My little 6Pro has been tested and found the reason why its BIAS looks so strange, because the power supplier is bad. After changing a new one, the RMS of BIAS becomes little to 15. And I have seen so many new & bigger CCDs, so good and so expensive, but I do not think that I can buy....

Same again Robin, my CGEM has a function "precise goto" that is like yours, last night I tried it: for M57, it lets me 1st to slew to beta Lyra, then centre it in eyepiece, then give the cordinates of M57, then just click ENTER, that's OK. Anyway so far I feel it is cool

Robin, I use CdC,too. I have never connected with CGEM. CGEM has a autoguide port, if I need a signal-wire which has one end inserted into the autoguide port and the other into PC's port? I have WATEC120N+ for slit-viewing for LHIRES III, 120 is connected to PC by video grabber, I'd like to know if this can be recognized by CdC to perform chart's functions, such as autoguide, accurate-pointing, etc. ? My CdC is 2.76c version.

Cheers,
Dong. Li