Q. Can you veiw the telescope image remotely in real time?

A. Not really real-time. The ST-7 is an integrating CCD and requires 30 sec or so to download the image. IT would be kind of like slow-scan TV.

Q. how many measurements can your system make in a night at one minute exposure? 100's?

A. Yes, several hundred.

Q. To what magnitude would a one minute exposure extend?

A. About 14th depending upon the filters used and the photometric accuracy required.

Q. What percentage of the telescopes field of view is covered by the CCD?

A. FOV at f/6.3 is 12 X 18 arcmin.

Q. Is the system automated to the point where it can be pre-programed to make observations night after night without supervision?

A. Yes and No....I have the software done but the weather station is not yet complete and until then, I don't trust the weatherman enough to just let it go without some supervision.

Q. You have chosen an 8-inch Meade LX200. Does Celestron do? Which is better, Meade or Celestron?

A. The Meade LX-200 was my choice because the Celestron equivalent was not yet available. The new Celestron does not keep the PEC in memory so when the scope is turned off, the corrections go away and it must be reprogrammed again. This reason alone is enough to go with the Meade.

Q. With your Meade LX200 and ST-7, a pixel corresponds to 1.4arcsec. > Does a star image at a good seeing fall within a pixel?

A. No, even the dimmest stars ususally subtend 3-4 or so pixels.

Q. Does a cloud sensor work well? Has it ever failed and the telescope got wetted by rain?

A. I have not depended entirely on the cloud sensor to detect when to open the observatory. I does fail in some conditions and I plan to build a rain sensor to alleviate the problem.

Q. In the article, you said you had to recenter the star between frames, implying the tracking was not very good, to what degree is your tracking off?

A. I just meant that it is a good idea to center and sync the scope on long slews. The telescope tracks very well. I did 9 hour runs without ever re-centering the star.

Q. We are having horrible tracking problems, even after programing the mount.

A. Your problems may result form poor polar alignment, poor SmartDrive programming or a faulty telescope drive. The LX-200 is very capable of excellent tracking and should do it, or something is wrong. You need to find an experienced LX200 user close to you to find out what the problem is.. Don't give up..It may be something very simple.

Programming the mount does not help with long term tracking, only with the short term periodic error of the worm drive gear. Poor SmartDrive programming can induce long term tracking errors if say the East corrections are longer in duration than the West corrections. This results in a net drift for each SmartDrive cycle.

Clear the SmartDrive programming and concentrate on polar alignment. Also make sure the rate is correct and not lunar or solar. The scope should keep a star on the CCD chip for a long time..I would think several hours.

Q. Did you have to balance the telescope whith the ccd camera on? We have balanced the telescope and reunbalanced the telescope and it seems to have little effect on the tracking. We have an ST-8 CCD camera.

A. I use the Meade weight system to balance it..but you are right..it did not affect the tracking. I put it on to reduce stress on the gears and motors.

Q. The camera is to big to do polar alignment procedures,

A. Just put it upside down on the mount. See the pictures on this WWW site.

Q. I am interested in knowing what kind of accuracy you are getting in B and V bandpasses and the exposure times required to get them. How faint do you typically work with your setup?

A. I am getting .005 to .03 mag accuracy in V. Its all a function of signal to noise. The brighter stars require less exposure to get good results. I have recently done 13-14 mag. stars with a 3 minute exposure and gotten +-0.01 accuracy. This is with an 8" aperture. The B filter results are not encouraging. Much longer exposure times are required (3-5X). I would suggest the VRI system. The B is workable if you have the patience.

Q. My own work will require 1% accuracy in V working down at 14th magnitude. This seems like it might be difficult through a filter and given the relatively low QE of the Kodak chip. I can tolerate exposure time of 15-30 minutes. Even with a high efficiency back-illuminated chip, I fear I may need some additional aperature. I find myself looking everywhere for some reassurance!

A. You should be able to get .01 accuracy with long exposure times (3-10 min.). Sometimes a comparison star of the correct magnitude may not be around complicating the process. Another bugaboo with long exposure times is telescope tracking accuracy.

Q. Can the ST7 be directly coupled to the C8 for autoguiding? I notice in your article that you used only short exposures and therefore did not make use of the autoguiding facility. If you did however, does the camera simply plug into the telescope motor control panel or is some additional hardware required?

A. I do not have a C8 or know anything about them. I only have experience with the Meade LX-200. On the LX-200 the ST-7 plugs directly into the LX-200 panel. It functions well. I use the autoguiding for long exposures only.

Q. Some occultation events are brief (tens of seconds). Is it possible to configure the ST7 camera to perform 'movie' style readout of a small image window?

A. Yes. A good programmer can do it by reading out only small portions of the CCD chip. This makes the image download process much faster.

Q. Can a stack of closely spaced short exposure images be stacked in memory ( e.g. one > 1s image every 3s)?

A. You may be able to do this. Readout time on a small window is quite short so I would think 3-5 sec would be quite possible.

Q. Is there any useful stellar photometery work that can be done without using a UBV filter wheel?

A. Very definitely yes. I am currently doing work on Cataclysmic Variables and we do not use filters at all and get very useful data. See http://www.astro.columbia.edu/~cba/

Q. What have you found the lowest temperature to be that you can run your computer and hard drive? (A concern when talking about Minnesota!!)

A. I had several nights last winter that went to 15 to twenty below zero F. The scope and camera worked well. The computer also had no problems. There is a light bulb heater with bi-metal thermostat in the electronics box to help keep it warm.

Q. Are the Computer mother board and hard drive common parts or did you use some "hardened" or "rough duty" components?

A. All cheap common parts.

Q. Is the custom controller you mentioned something you constructed or had custom built? Did you look into any commercial controller boards?

A. I built the controller board with mostly surplus parts and some components from Radio Shack. I did not investigate commercial boards. Most of these circuits are rather specialized.

Q. And lastly (and sad that such a question needs to be asked) have you had problems with vandals and have you made any effort to thwart them?

A. The observatory is located in a location not visible from the main road. We have had no problems so far, and really don't expect any. It looks too much like a large bee-hive. I have thought about printing the words ..DANGER...EXPERIMENTAL HORNET HIVE on the enclosure, but have not yet done so.

Q. Does your software work with an ST-6 camera?

A. The ST-6 will not work with my software. Only an ST-7 will work. The ST-6 does not have a software driver interface.

Q. I am very interested in more detail about the thermoelectric coolers you used to keep the enclosure dry.

A. If you are familiar with the little portable refrigerators which plug into a car's cig lighter then you are halfway there. I bought a surplus thermoelectric module with heat sink atttached for $44.95, built a small enclosure for it which is vented to the outside, hooked it up to a power supply and timer and its a dehumidifier. That's about it.. Seems to work great. Surplus catalog Herbach and Rademan, part no. TM96HVC2855. H & R phone = 800-848-8001. www.herbach.com. If you do an Internet search on "Peltier effect" you will find all kinds of info. There are two of three companies which use the modules for cooling, but I have not seen any used for dehumidification.

Q. What problems would you anticipate if the design was modified to include a larger aperture Meade LX200.

A. Probably no significant problems. I choose the 8" as a base because it theoritcally should have less flexure, but who really knows. The enclosure would need to be made larger to house a 10 or 12". The lid weight may be a problem. I built mine out of 2X4's and 3/4 inch plywood. Its quite heavy. Some other contruction materilas such as fiberglass would be much lighter.

Q. I would be particullarly interested in more information on the SBIG software-driver library.

A. The software driver library is available on the SBIG WWW page.

Q. If I were to go with a 10", what would you estimate the size increase for the enclosure to be?

A. If I were to build the enclosure again, I would make it about 6 inches larger. Everything just barely fits now, so a 10 inch would probably fit in an enclosure about 6-8 inches larger. The lid would also need to be a couple inches higher. You would need to measure to make sure.

Q. Could the enclosure be made of 1/2" rather than 3/4" plywood to decrease the weight?

A. I would go with 1/2 inch next time I did it..so should you.