Digital-Electro-Mechanical Reference Information

Info

Information sources include Comsat/LM documentation, GBT Memos, and information from Green Bank staff personnel.

Electronics

    Receiver Turret Locations 

GBT Gregorian Receiver Locations on the Turret
Turret Position Turret Angle (Deg.) Receiver Receiver Band
N1 359.68 1_2  (1.15-1.73 GHz) L
N2 299.65 4_6  (3.95-5.85 GHz) C
N3 259.65 Vacant n/a
N4 219.66 12_18  (12-15.4 GHz) Ku
N5 179.65 2_3  (1.73-2.60 GHz) S
N6 139.64 18_26  (18-26.5 GHz) K
N7 99.69 Holography n/a
N8 59.66 8_10  (8-10.1 GHz) X

    Receiver Circular Polarization Optimization 

        S-Band
Sky Frequency (MHz) Gain X Setting Gain Y Setting
< 1900 0 +2.5
1953 0 +2.0
2006 0 +1.0
2165 0 ±0.0
2218 0 -1.0
2324 0 -3.0
2370 0 -4.74
2380 0 -5.11
2430 0 -7.0
> 2483  +3.0 -2.0
        L-Band
Sky Frequency (MHz) Low Cal High Cal Gain X Setting Gain Y Setting Phase
1300 2.1 28.0 4.6 ±0.0 56.0
1400 2.1 28.2 4.6 ±0.0 52.0
1500 2.1 28.2 4.6 ±0.0 50.0

1600

 2.2 31.4 4.6 ±0.0 46.0

Cryogenics     

    Compressors Supplying Receivers

Compressor #1  Compressor #2 Compressor #3  Compressor #4  Compressor #5 Compressor #6 
Prime Focus Q-Band L-Band S-Band K-Band Spare
none none C-Band X-Band Ku-Band none

Telescope Limits     

    Azimuth Limits (CW) Deg.

Software Pre Limit Redundant Pre Limit Final Limit Redundant Final Limit Cleo Indicated Position
90.200 90.674 91.220 91.628 92.200 450

    Azimuth Limits (CCW) Deg.

Software Pre Limit Redundant Pre Limit Final Limit Redundant Final Limit Cleo Indicated Position
270.200 269.729 269.200 268.564 268.200 -90

     Elevation Limits (Up) Deg.

Software Pre Limit Redundant Pre Limit Final Limit Redundant Final Limit
95.100 95.355 95.593 95.854 96.084

    Elevation Limits (Down) Deg.

Software Pre Limit Redundant Pre Limit Final Limit Redundant Final Limit
4.900 4.663 4.411 4.155 3.919

    Subreflector Actuator Software Limits 

Actuator Retracted Limit (inches) Extended Limit (inches)
Y1 98.64 135.69
Y2 97.88 136.57
Y3 97.88 136.57
X1 114.24 144.85
X2 114.24 144.85
X3 56.70 76.11

Telescope Movement Rates     

    Azimuth - Elevation 

Azimuth (Full Slew) Elevation (Full Slew)
Degrees/Min Arc Minutes/Min Degrees/Min Arc Minutes/Min
35.8 2150 18 1080

    Degree/Min to Arc Minutes/Min Conversion Table 

Deg/Min = Arc Min/Min   Deg/Min = Arc Min/Min   Deg/Min = Arc Min/Min   Deg/Min = Arc Min/Min
1

 

 60 11

 

 660 21

 

 1260 31

 

 1860
2

 

 120 12

 

 720 22

 

 1320 32

 

 1920
3

 

 180 13

 

 780 23

 

 1380 33

 

 1980
4

 

 240 14

 

 840 24

 

 1440 34

 

 2040
5

 

 300 15

 

 900 25

 

 1500 35

 

 2100
6

 

 360 16

 

 960 26

 

 1560 36

 

 2160
7

 

 420 17

 

 1020 27

 

 1620 37

 

 2220
8

 

 480 18

 

 1080 28

 

 1680 38

 

 2280
9

 

 540 19

 

 1140 29

 

 1740 39

 

 2340
10

 

 600 20

 

 1200 30

 

 1800 40

 

 2400

Conversion Formulae

Degrees Per Minute to Arc Minutes Per Minute:   Deg/Min   x   60 Arc Min/Deg'  =  Arc Min/Min

Arc Minutes Per Minute to Degrees Per Minute:  Arc Min/Min   ÷   60   =   Degrees Per Minute  

Observing Operations

    Pointing Coefficients 

Gregorian Pointing Coefficients (Arcmins)
Azimuth Positions Values Elevation Positions Values
D00 -1.4185 D00 -13.7722
B01 .0000 C10 .0038
D01 .0000 D10 .0648
B11 .0038 B01 13.5407
A11 -.0648 D01 13.6843
C21 .0000    
D21 .0000    
Subreflector XYZ control values (Xt = -.14) (Zt = -.06) 

 

Prime Focus Pointing Coefficients (Arcmins)
Azimuth Positions Values Elevation Positions Values
D00 -0.9778 D00 -9.3837
B01 1.0878 C10 -0.0495
D01 -1.3523 D10 0.0617
B11 0.0495 B01 11.7268
A11 0.0617 D01 8.6382
C21 .0000    
D21 .0000    

 

Prime Focus Pointing Coefficients - Focus Tracking Off (Arcmins)
Azimuth Positions Values Elevation Positions Values
D00 -0.9778 D00 3.1300
B01 1.0878 C10 -0.0495
D01 -1.3523 D10 0.0617
B11 0.0495 B01 6.9000
A11 0.0617 D01 -10.0000
C21 .0000    
D21 .0000    
Assumes axial focus (Y = 1030mm or 40.55 in.) and lateral focus (X = 560mm or 22.05 in.)

Prepared by: Dave Rose

Last modified: 14Nov02