Polar Alignment & Database Errors
in ROM 3.30 (Classic)
Subject: Database Errors in ROM 3.30 for LX200 Classic
From: Ralph Pass
There are 250 in the main Meade star database. The table below is a list
of the stars in the database, the errors in RA and Dec (in minutes for RA, in arc minutes for DEC), and the total error (in arc
minutes). These numbers are for ROM 3.3 or earlier (and are true also for ROM 4.2) The star names are omitted (they were included
in the tables for parts 1 and 2) simply to reduce the number of characters in the message.
See the description afterwards for detailed column description and explanation
of how the numbers were created. Please note that N/A means that this star does not have a location in the star database used.
Meade RA Dec Error Meade RA Dec Error
1 0.24 0.84 3.29 126 0.09 0.44 0.67
2 0.03 0.40 0.46 127 0.05 -0.02 0.51
3 0.19 0.43 2.80 128 0.15 -0.02 1.50
4 0.16 1.16 1.28 129 0.12 0.60 1.84
5 0.05 1.06 1.21 130 0.19 0.06 1.04
6 0.07 1.10 1.46 131 0.04 0.23 0.39
7 0.14 0.68 1.32 132 0.12 0.13 1.04
8 0.15 1.25 2.51 133 0.10 0.64 1.39
9 0.12 0.46 0.99 134 0.14 0.08 2.05
10 0.07 0.36 0.83 135 0.06 1.20 1.48
11 0.07 0.72 1.09 136 0.13 0.75 1.70
12 0.21 -0.36 1.58 137 0.04 1.00 1.05
13 0.14 0.35 1.19 138 0.04 0.80 1.02
14 0.08 0.09 1.09 139 0.18 0.46 1.71
15 0.12 0.43 0.99 140 0.05 0.21 0.56
16 0.01 0.42 0.43 141 0.13 -0.02 1.43
17 0.21 0.40 2.86 142 0.06 0.25 0.87
18 0.16 0.90 2.17 143 0.04 0.09 0.43
19 15.35 -0.42 3.06 144 0.09 1.98 2.08
20 0.01 0.04 0.09 145 0.10 0.41 1.41
21 0.08 1.59 1.84 146 0.10 0.15 1.20
22 0.03 1.27 1.35 147 0.14 0.26 1.98
23 0.25 0.29 2.2 148 0.09 -0.26 1.05
24 0.16 0.26 1.82 149 0.20 0.77 2.40
25 -0.02 0.68 0.70 150 0.04 1.09 1.13
26 -0.01 0.36 0.39 151 N/A
27 0.10 -179.56 179 152 0.11 0.92 1.46
28 0.21 0.80 1.17 153 0.12 0.69 1.01
29 0.03 0.19 0.46 154 -1.52 0.64 20.31
30 0.13 0.80 1.74 155 -8.99 219.92 236.87
31 0.11 0.68 1.72 156 0.12 0.49 0.68
32 0.09 -0.28 0.86 157 0.12 0.09 1.31
33 0.15 -0.01 2.13 158 0.15 -0.13 1.69
34 0.18 1.20 3.00 159 -0.01 1.18 1.19
35 0.18 -0.47 2.36 160 0.15 0.06 2.23
36 0.03 1.00 1.04 161 0.06 0.26 0.42
37 0.06 0.37 0.91 162 0.06 0.15 0.69
38 0.08 0.70 1.16 163 0.13 0.06 0.62
39 0.02 0.46 0.51 164 0.02 -0.05 0.18
40 0.12 0.34 1.73 165 -0.71 -0.18 9.54
41 0.11 -0.41 1.68 166 -13.74 32.15 159.06
42 0.24 -0.42 2.52 167 -9.97 0.42 148.53
43 0.04 0.93 1.10 168 0.12 -0.01 0.80
44 0.08 0.74 1.35 169 0.16 0.96 2.41
45 0.19 0.21 2.53 170 N/A
46 0.14 0.21 2.00 171 0.25 0.49 3.53
47 0.16 1.86 3.08 172 -0.04 0.44 0.71
48 0.12 0.47 1.79 173 0.10 1.05 1.78
49 -11.00 0.24 164 174 0.07 -4.87 4.98
50 0.17 0.72 2.69 175 0.00 1.09 1.09
51 0.16 0.40 2.29 176 0.13 0.50 1.03
52 0.08 0.41 1.04 177 0.02 -0.31 0.37
53 0.02 0.31 0.42 178 0.12 -0.02 1.61
54 0.13 0.73 2.08 179 0.19 0.61 2.54
55 0.09 0.84 1.41 180 0.10 0.54 1.54
56 0.12 0.39 1.76 181 0.11 0.71 1.52
57 0.18 -0.16 1.92 182 0.16 -0.17 0.88
58 0.20 -0.26 2.38 183 0.05 -0.12 0.65
59 0.09 -0.49 1.35 184 0.15 0.62 1.86
60 0.13 0.34 1.73 185 0.04 0.93 1.12
61 0.17 0.97 2.59 186 0.13 1.01 1.47
62 0.09 0.80 1.52 187 0.17 0.23 1.09
63 0.05 0.42 0.61 188 0.11 0.85 1.75
64 0.14 0.22 2.00 189 0.01 -0.02 0.15
65 0.12 0.50 1.36 190 0.23 1.73 3.78
66 0.04 0.17 0.57 191 0.04 1.66 1.74
67 -0.06 0.34 0.97 192 0.08 1.86 2.10
68 0.04 0.85 0.90 193 0.02 0.29 0.38
69 0.12 0.46 1.22 194 0.01 0.45 0.45
70 0.04 0.08 0.52 195 0.09 0.58 0.97
71 0.03 0.43 0.56 196 0.24 0.45 2.91
72 0.20 -0.13 2.67 197 0.13 -0.71 1.35
73 0.10 0.12 1.02 198 0.08 0.62 0.95
74 0.08 -0.33 0.96 199 0.09 0.96 1.41
75 0.11 -178.62 178 200 10.11 0.78 148.10
76 0.09 0.95 1.68 201 0.18 0.29 1.98
77 0.08 -0.49 1.00 202 0.06 0.32 0.76
78 0.10 -0.06 1.23 203 0.04 1.15 1.28
79 0.10 -0.06 1.23 204 0.05 0.47 0.77
80 0.05 0.16 0.77 205 0.14 -0.52 1.71
81 0.12 0.27 1.64 206 0.10 1.36 1.63
82 0.09 0.14 1.30 207 0.07 0.59 1.13
83 0.02 -599.38 599 208 0.10 0.52 1.43
84 0.14 0.58 2.02 209 0.11 1.18 1.73
85 0.09 0.65 1.10 210 0.09 0.17 1.20
86 0.22 0.35 1.69 211 0.06 -0.07 0.92
87 0.17 0.55 1.60 212 0.06 0.75 1.04
88 0.04 0.83 1.04 213 0.08 0.51 1.17
89 0.08 -0.39 0.90 214 0.08 0.77 1.21
90 0.02 -0.79 0.83 215 0.16 0.24 2.16
91 0.05 1.15 1.18 216 0.07 0.82 1.26
92 0.16 0.68 1.42 217 0.17 0.97 2.31
93 0.07 0.77 1.12 218 0.11 0.76 1.62
94 0.07 0.58 0.82 219 0.19 -0.64 2.87
95 0.15 -0.27 2.31 220 0.04 -0.68 0.90
96 0.08 -0.81 1.02 221 0.08 1.11 1.60
97 0.03 -0.09 0.33 222 -0.04 1.20 1.23
98 0.08 0.77 1.37 223 0.13 -0.03 1.73
99 0.08 1.01 1.14 224 0.03 0.14 0.33
100 -0.08 0.43 1.27 225 0.03 0.09 0.52
101 0.12 0.14 0.65 226 0.15 1.37 2.67
102 0.11 -0.07 1.60 227 0.16 1.85 3.04
103 0.15 0.41 1.70 228 0.05 0.20 0.69
104 0.15 0.35 1.15 229 0.06 0.48 0.82
105 -0.01 0.83 0.84 230 1.58 -6827.04 6827.07
106 0.17 1.30 2.07 231 0.04 0.51 0.62
107 -0.01 -0.11 0.17 232 0.07 0.80 1.09
108 0.16 0.48 1.40 233 0.02 1.16 1.20
109 0.04 0.59 0.65 234 0.13 0.44 1.79
110 0.10 0.46 1.14 235 0.07 -0.07 0.48
111 0.06 -0.03 0.80 236 0.10 1.39 1.48
112 0.09 0.33 1.36 237 0.11 1.47 2.20
113 0.06 0.39 0.56 238 0.15 0.19 2.27
114 0.12 -0.09 1.68 239 0.08 0.04 1.17
115 0.08 0.27 0.79 240 0.14 0.76 1.87
116 0.01 0.24 0.26 241 0.14 0.42 2.15
117 0.18 -0.60 2.56 242 0.14 0.94 1.69
118 0.09 -0.35 0.78 243 0.08 0.99 1.16
119 -0.01 0.54 0.54 244 -0.01 -0.58 0.59
120 0.16 0.06 2.30 245 0.08 -0.22 1.05
121 0.13 -0.37 0.97 246 1.10 1.23 15.90
122 0.03 0.63 0.67 247 0.19 1.14 2.75
123 0.02 -0.35 0.43 248 0.14 0.43 1.97
124 0.21 1.71 2.44 249 0.12 0.78 1.96
125 0.04 -0.24 0.57 250 0.15 1.36 1.45
The table was created by using the SAC star database (which is a corrected SAO database). Star locations were converted to apparent
positions by accounting for precession, nutation, and aberration using formulae from Meeus' book. The date for the comparison was
1 April 1995.
I take full responsibility for properly dumping the numbers in the LX200 database, for the programming of the routines to use
the star database, and for computing the errors.
There is, however, a workaround the errors for polar alignment if you have the 64K object library (e.g.,
ROM 3.3, ROM 4.2, or the library option for earlier versions). The key is to use the SAO star locations and to manually do the
alignment.
Try the following steps:
- Do two iterations of the normal polar alignment procedures. This means to select polar alignment, press GoTo instead of
Enter on the first option. Note the Meade number of the star selected as the second star.
- Tell the LX200 to use the SAO database (STAR, ENTER, UP/DOWN arrow to get to SAO, ENTER, MODE).
- From the list of Meade numbers versus SAO numbers, find the SAO number for the Meade number found in step 1.
- Repeat the following until you are close enough
- GoTo Polaris (STAR, 308, GoTo ). After the beep, press GoTo again.
- After this beep, proceed.
- Use the manual adjustments on the wedge to place Polaris at the center (I assume you are using an eyepiece with crosshairs,
so Polaris should be under the crosshairs).
- GoTo the other star (STAR, <SAO NUMBER FROM STEP 3>, GoTo ). After the beep, press GoTo again. After this beep, proceed.
- Use the keypad controls to place the star under the crosshairs and when done, press and hold ENTER until a beep. The message
on the display should say matched coordinates.
- Repeat back to Step 5 until you are satisfied with the alignment.
Note: I am usually satisfied after four iterations starting at step 5.
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