Meade Standard Tripod Leg ETX-90EC, High-Latitude Tripod Leg ETX-90EC, Dec.at

4.Each table tripod is equipped with two adjustable tripod legs: The standard tripod leg is used at observing latitudes as shown in the box in step 5 and has a dual latitude label attached (Fig. 15). The high-latitude tripod leg is shorter and is used at higher observing latitudes. Based on the observing latitude determined in step 3, set aside the tripod leg that is not to be used.

5.Locate the two mounting holes on the bottom of the telescope drive base. Mount the appropriate adjustable tripod leg (as determined in step 4) to the drive base using the following latitudes:

Standard Tripod Leg (ETX-90EC)

32.5° to 48.5° uses high-latitudehole (2, Fig. 16).

22° to 35.5° uses alternate hole (3, Fig. 16).

High-Latitude Tripod Leg (ETX-90EC)

56° to 66° uses high-latitudehole. 44° to 55° uses alternate hole.

Standard Tripod Leg (ETX-125EC)

33.5° to 49.5° uses high-latitudehole. 23.25° to 36.5° uses alternate hole.

High-Latitude Tripod Leg (ETX-125EC)

CHAPTER

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7

2 8

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Dec.at 90°

3

46

Fig.16: Example of Polar Alignment Using the #880 Table Tripod and ETX-90EC. (1) Standard tripod leg with latitude scale; (2) High-latitude hole; (3) Alternate hole; (4) Fixed tripod legs; (5) Declination pointer; (6) Thumbscrew;

(7) R.A. scale pointer; (8) #1422 low-latitude balance weight.

8. Note the line and arrow extending from the telescope tube in

Fig. 16. This line defines the telescope’s polar axis. Lift the

entire telescope, including tripod, and place the telescope on

a firm and level surface so that this axis is pointing due North

56.6° to 67° uses high-latitudehole. 44.5° to 56.5° uses alternate hole.

Thread the appropriate leg into the required hole to a firm feel only.

6.A small thumbscrew (6, Fig. 16) is attached to both the standard and high-latitude tripod legs. Loosening the thumbscrew allows the outer section of the leg to slide over the inner section, so that the leg can be extended. If using the standard tripod leg, extend the leg so that the center of the thumbscrew head aligns with the latitude of the observing location on the scale. Retighten the thumbscrew to a firm feel. (If using the high- latitude tripod leg, complete the adjustment of the leg extension in step 9.)

Example: The latitude of New York City is 41°. The tripod leg should be extended so that the center of the thumbscrew is set next to the 41° reading on the scale.

Fig.15:

Example of

Standard Tripod

(i.e., if the location of Polaris, the North Star, is known then

point the telescope directly at Polaris).

9. If using the high-latitude tripod leg in the Northern

hemisphere, extend the leg until the telescope’s polar axis

points to Polaris, or due North, an alignment obtained by

sighting along the telescope tube with the telescope oriented

as shown in Fig. 16.

NOTE: Observer’s located in the earth’s Southern Hemisphere (e.g., South America, Africa, Australia, etc.) should point the telescope’s polar axis due South.

10.With the telescope now polar-aligned the table tripod should not be moved, or else polar alignment will be lost. Motions of the telescope (e.g., to locate and/or track objects) should be effected only (a) by loosening the locks (6 and 10, Fig. 1), which permits the optical tube to be moved freely within the telescope mounting, or (b) more generally, with the locks in their “locked” positions, by using the arrow keys of the Electronic Controller.

NOTE: For almost all astronomical observing requirements,

CAUTION:When using the #880 Table Tripod Leg Latitude with the ETX-90EC, the optional #1422 Low- Scales.

Latitude Balance Weight is recommended if

the telescope is to be polar aligned below 30°, or if heavy accessories are attached to the eyepiece-end of the telescope. The low-latitude balance weight is recommended for the ETX-125EC at all observing latitudes and is included as standard equipment with the #881 Table Tripod.

NOTE:With the standard tripod leg threaded into the appropriate hole in the drive base, the latitude scale may be at an inconvenient position for reading (e.g., the scale faces the drive base). This situation can be remedied by unthreading the leg, removing the thumbscrew, rotating the inner leg 180°, then reinserting the thumbscrew. The scale should now be readable when threaded back into the telescope base.

7.Loosen the vertical and horizontal locks (6 and 10, Fig. 1) and rotate the telescope so that it is oriented as shown in Fig. 16. Tighten the vertical and horizontal locks. In this orientation the telescope’s optical tube is lined up parallel to the tripod’s adjustable leg.

approximate settings of the telescope’s latitude and polar axis are acceptable. Do not allow undue attention to precise polar alignment of the telescope to interfere with your enjoyment of the instrument. In those unusual cases where more precise polar alignment is desirable, refer to APPENDIX C, page 24.

Fig. 17: Locating Polaris.