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...
42850
Rick Wiggins
meunage
Jun 1, 2005 3:11 pm
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...
42851
Rick Wiggins
meunage
Jun 1, 2005 3:36 pm
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...
42852
Charles Bell
quantumhyper...
Jun 1, 2005 3:45 pm
... 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...
42853
Wodaski Yahoo
rwodaski
Jun 1, 2005 3:48 pm
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...
42854
Keith S
kasism
Jun 1, 2005 4:09 pm
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...
42855
Matt Thomas
matt_e_thomas
Jun 1, 2005 4:16 pm
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...
42856
Rick Wiggins
meunage
Jun 1, 2005 4:18 pm
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...
42857
Richard Bennion
rbennion
Jun 1, 2005 4:57 pm
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...
42858
Richard Bennion
rbennion
Jun 1, 2005 5:09 pm
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...
42859
jmize
sfojmize
Jun 1, 2005 5:13 pm
Keith; Plz keep me informed as I'd be interested in hearing what you discover. Thkx...joe :) "May You Go Among The Imperishable Stars" Joe Mize:...
42860
Matt Thomas
matt_e_thomas
Jun 1, 2005 5:22 pm
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...
42861
Steve Reilly
sreilly22911
Jun 1, 2005 5:27 pm
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...
42862
Richard Bennion
rbennion
Jun 1, 2005 5:40 pm
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...
42863
Chris Curran
chriscurran
Jun 1, 2005 5:51 pm
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...
42864
Dennis Persyk
dennis_persyk
Jun 1, 2005 5:56 pm
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...
42865
Matt Thomas
matt_e_thomas
Jun 1, 2005 5:59 pm
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...
42866
Richard Bennion
rbennion
Jun 1, 2005 5:59 pm
Dennis, The guide star is dark subtracted. rb Richard A. Bennion CCDWare Publishing http://www.ccdware.com Ewell Observatory http://www.ewellobservatory.com ...
42867
Richard Bennion
rbennion
Jun 1, 2005 6:10 pm
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...
42868
Keith S
kasism
Jun 1, 2005 7:29 pm
... 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...
42869
Matt Thomas
matt_e_thomas
Jun 1, 2005 7:53 pm
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...
42870
Paul K
paulkccd
Jun 1, 2005 8:15 pm
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) ...
42871
Richard Bennion
rbennion
Jun 1, 2005 8:37 pm
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...
42872
Dennis Persyk
dennis_persyk
Jun 1, 2005 8:41 pm
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...
42873
Matt Thomas
matt_e_thomas
Jun 1, 2005 8:59 pm
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...
42874
Wodaski Yahoo
rwodaski
Jun 1, 2005 9:08 pm
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?...
42875
Rick Wiggins
meunage
Jun 1, 2005 9:09 pm
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...
42876
laurenc319
Jun 1, 2005 9:20 pm
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...
42877
Matt Thomas
matt_e_thomas
Jun 1, 2005 9:32 pm
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...
