• Setting circles
• Dew removal
• 201XT

Setting Circles:

The DEC circle is pretty simple. However, reading it accurately can be tricky. (More to be written).

The RA circle is really clever. The circle sits between the scope and the base, and each of the scope and base have an index mark. The circle can be manually turned independently of everything. When the scope is unclutched for manual RA turning, then the circle stays with the base. When the scope is moved with keypad, then the circle moves with the scope. There are three ways to use the circle (the third one is way cool). These explanations assume northern hemisphere, so ignore the inner dial numbers and use the outer dial numbers only for both scope and base indexing. Also, a polar aligned scope is assumed.

1. When using the LX200 in its full electronic GOTO mode, the circle looks good but is useless. Treat it as a decoration. It cannot be read for sidereal time or RA when in this mode.
2. When using the LX200 with no power:
   • turn the circle until the base index mark reads the current sidereal time
   • unclutch RA axis and turn scope (with manual knob if desired, and / or with clutch partly engaged to provide some friction). The scope index mark can be used to read current RA.
   • manually move circle to keep up with sidereal time as needed
   • (alternatively, one can set the RA of a known object by moving the circle into alignment with the scope mark then immediately turning the scope to the desired RA again using scope mark)
3. With a powered scope that is not going to be used in GOTO mode, but is intended for "manual finding" (perhaps for practice) something nifty happens. Whether the RA clutch is engaged or not the circle actually keeps tracking clockwise with the stars, such that it will continually read sidereal time on the base index and the scope index will always read an accurate RA. (Unless you do a GOTO, then you're back to mode one above).
   • power-up and read sidereal time off the keypad then put the keypad out of the way leaving power on
   • manually turn circle so that base index mark reads sidereal time (as long as the keypad or a computer is not used to move the scope, it will keep reading sidereal time)
   • manually move scope reading RA off the scope index mark ... all night long.

201XT:

• See Guido Pasi's excellent 201XT site
• Set delay time to 2 sec (should only need to be done once). I'm impatient, and the default is 5 sec before guiding begins.
• Let it warm up for 15 min before taking dark frame, and always remember to take a new dark frame after changing exposure time.
• If focus is really lost, remember that the 201XT with 1.25" nose is parfocal with the Meade 9mm guiding eyepiece
• Calibrate:
  • only if very different DEC since last time (my default of +30° should work from southern horizon clear up to +60°
  • set LX200 backlash to its normal setting
  • use default 201XT settings for calibration times (2 seconds for both RA and DEC), or in Guide speed the LX200 slow motion controls can be used to time a 1/10th chip (one count shift) motion.
• ETX use:
  • Extension tube not needed on rear adapter for top side 26mm eyepiece to be par-focal.  It is needed for the 9mm eyepiece.
  • focus / centering (need to figure this out)
  • want brightness values between 10 and 95
    • use mag 6-9 stars,
    • 2-7 sec exposures
  • To move the centroid as displayed in "xy" format
    • when mounted on rear port: east increases x, north increases y
    • when mounted in right angle port: east increases x, south increases y
• Consider guiding with LX200 backlash set to a low value (like 0). Start guiding and wait for the first 0 correction in DEC after the first non-zero correction. DEC error should ramp up to 2 or 3 and then go to 0. Then start exposure.
• Updated "one-button" control chart below: