Keith; I ran into almost the same problem last week. Are you sure your alarm says "EL" vs. "EH"? I reveived EH. The Polar Bear Chiller owner's Manual says...
Hi Steve, Congratulations on your image. This is pretty good given the exposure time. I did notice the red shadows on some stars and wondered if that is a...
Hi Ron, I agree that dithering will provide better imaging providing many other constraints are also met. I think it is important to point out that to removal...
... produces ... be ... Is there a way to calculate how long to reach ~1500 ADU" versus star magnitude? I found the above to be very useful and wonder if...
I agree with #1, but #2 may be more forgiving than you realize. I am nowhere near sky-limited at my location (the suggested exposure time is 93 minutes!), but...
Joe, Thanks for the very good information! Yes it does say EL.. I checked it several times to be sure, but I will check the water temp issue to see. The...
Richard, ... Something doesn't seem right with your numbers. The typical rule of thumb for using an AO-7 is a mag 10 star through a f/10 scope requires a 0.1...
Hi Ron, I agree with you. I didn't mean that one has to exceed sky-limited exposure. I meant that one should get to the point where the image noise is...
Calculating this would be way over my head, but very useful indeed! I know that it takes 5 seconds to get to 1500 ADU on a mag 11 star because I guide on them...
The AO7 will often be used at ADUs less than 1000. I have used an A0-7 at 5hz on a guide star with 300 ADU. Totally different ball game. The number I stated...
Richard, ... I'm not sure why it would be a different ball game. Regardless of your guiding choice (mount or AO-7), you still need a large enough SNR on the...
A bit curious here as well. I haven't followed the entire thread but I do know that the values shown for brightness on the AO7 is different that on the guiding...
AO-7s use completely different guiding principles. One is tilting a mirror every 1/10 of a second...the other is moving a 100 pound mount. You cant move a 100...
Keith, Quite cold? A thought if you're comfortable taking it apart... Re-seat any socket mounted chips on any circuit boards in there. Ditto other connectors...
Hi Charles, I assume that 1500 ADU is the bias-subtracted intensity. If not, subtract the bias and use that value. delta m = 2.51 x log10 R where delta m is...
Richard, ... Yes, this is absolutely true - which is why you can use short guide exposures with the AO-7 and why you would use long guide exposures when...
Dennis, The guide star is dark subtracted. rb Richard A. Bennion CCDWare Publishing http://www.ccdware.com Ewell Observatory http://www.ewellobservatory.com ...
Matt: Take a look at this data: ************** Seeing measurements: Data acquired on DEC axis with drift subtraction with no relay movement. A 0.2 second...
... seat ... their ... Chris, Well cold is relative term, for us Texans anything below 40 starts to break out the overcoats but yes we actually do get tems in...
Richard, Good data, but it only proves that longer exposures are necessary to smooth out seeing induced errors. This has no relevance to the question at hand...
Hi Dennis, You're on the right track, but your calculation is a bit off. The R calculation should be: R = 10^[(delta m)/2.51] (you had the ^ terms swapped) ...
You can get a centroid on a guide star as low as 100 ADU over the background ADU, but the fact is, you cant guide on it. "This would translate to the fact that...
Hi Paul, Yes, I was concerned that my result did not pass the reasonableness test. I hate it when I post something so obviously silly. I was about to post the...
Richard, ... Come on, there is no need to play these games. I said: "If the AO-7 can successfully guide on a star with a 0.2 second exposure, this means that...
Have either of you guys contacted SBIG to learn whether there are, in fact, differences in the AO-7 guide algorithms and mechanics and conventional guiding?...
I decided to post this statement of advice in support of this mornings post by Jay Ballauer regarding keeping things simple and not obsessing over individual...
Hi Rick, Nice post and thanks for taking the time to write it. It makes sense to think about your system in as a whole, look for the weak spots and correct...
Ron, ... In terms of how CCDOPS implements AO-7 guiding, I have not. Same is true for CCDSoft and MaxIm. However, the mechanics involved are documented quite...
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