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HP Forum Archive 15

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HP-41CX sun position program.
Message #1 Posted by Michel Beaulieu on 28 Nov 2005, 7:53 p.m.

Hi. I'm looking for a program that can give me the position of the sun in RA and DEC for a HP-41CX with the curent date and time of the calculator.

Or at least an algorithm that will help me do the program... I just buy a 11" celestron for school with a "GO TO" for 40 000 objects in the sky BUT the sun has not been program and it is often difficult to point correctly the sun. But with RA and DEC from my CX i will just enter them and GOTO!

Thanks Michel Beaulieu Canada

      
Re: HP-41CX sun position program.
Message #2 Posted by Karl Schneider on 28 Nov 2005, 10:07 p.m.,
in response to message #1 by Michel Beaulieu

Michel --

I have a program written by Tom Sherman in 1986, which he sent to me within the past several years. It requires an HP-41 Navigation Pac and a 41CX or 41C/CV with Time Module. (A 41C will also require a Memory Module or Quad Memory Module.)

Given the latitude and longitude of a location, plus the date and time from the clock, it will calculate the angles of altitude and azimuth for the sun, the moon, four visible planets, and many navigational stars.

I'd like to make a few refinements to the program, but have not yet done so. I have written the program to magnetic cards.

-- KS

            
Re: HP-41CX sun position program.
Message #3 Posted by Trent Moseley on 28 Nov 2005, 10:21 p.m.,
in response to message #2 by Karl Schneider

I know it may seem redundant, however one must be extremely careful when viewing the sun. You MUST have a solar filter that is compatable with your telescope!

tm

      
Re: HP-41CX sun position program.
Message #4 Posted by Dave Shaffer on 28 Nov 2005, 11:44 p.m.,
in response to message #1 by Michel Beaulieu

Here is a BASIC program which will give the RA and DEC of the Sun to very high accuracy (a few seconds of arc) given year, date, and time (hours and minutes) as input. (Note, there are some extra variables printed in this version - helpful for debugging and generally checking what's happening). Note that the parallax of the Sun (which can be up to almost 10 arcseconds) is ignored. The RA, DEC are with respect to the center of the Earth. RA and DEC are in fractional hours and degrees - I'm not sure what your telescope wants.

10 DEFDBL A-H,J-Z
20 PI = 3.14159265#: TWOPI = 2# * PI: CONV = TWOPI / 360#
30 YEAR = 2000: MONTH = 8: DAY = 22: HOUR = 2: MIN = 0

get the time & date from the calculator instead

40 UTC = (TWOPI * (60# * HOUR + MIN)) / 1440# 50 DIM NDAY(12) 60 DATA 0,31,59,90,120,151,181,212,243,273,304,334 70 FOR I = 1 TO 12 80 READ NDAY(I) 90 NEXT I 100 YEARM = YEAR - 1900# 110 KDAY = INT((YEARM - 1#) / 4#) 120 JULDAY = 2415019.5# + YEARM*365# + KDAY 130 JULDAY = JULDAY + NDAY(MONTH) + DAY 140 IF(YEARM/4# - INT(YEARM/4#)) > .2 THEN GOTO 160 150 IF(MONTH > 2) THEN JULDAY = JULDAY + 1# 160 CENTURY = ( JULDAY - 2451545# ) / 36525# 170 STM = 24110.55# + CENTURY* (8640184.812866# + .093104#*CENTURY) 180 STM = STM/86400# - INT(STM/86400#) 190 STM = 2# * PI * STM: PRINT JULDAY,STM*12/PI 200 DAYS = JULDAY - 2451545# + (UTC/TWOPI) 210 SOLLON = 280.46# + .9856474# * DAYS 220 SOLLON = SOLLON - 360# * SGN(SOLLON)*INT(SOLLON/360#) 230 IF(SOLLON < 0) THEN SOLLON = SOLLON + 360# 240 SOLANOM = 357.528# + .9856003# * DAYS 250 SOLANOM = SOLANOM * CONV 260 SOLANOM = SOLANOM + TWOPI * SGN(SOLANOM)*INT(SOLANOM/TWOPI) 270 IF(SOLANOM < 0) THEN SOLANOM = SOLANOM + TWOPI 280 ECLLON = SOLLON + 1.915# * SIN(SOLANOM) + .02# * SIN(2#*SOLANOM) 290 ECLLON = ECLLON * CONV 300 ECLLON = ECLLON + TWOPI * SGN(ECLLON)*INT(ECLLON/TWOPI) 310 QUADRANT = ECLLON / (PI/2) 320 IQUAD = 1 + INT(QUADRANT) 325 PRINT ECLLON,QUADRANT,IQUAD 330 OBLIQ = 23.439# - .0000004# * DAYS 340 OBLIQ = OBLIQ * CONV 350 RA = ATN( COS(OBLIQ) * TAN(ECLLON) ) 360 IF IQUAD=2 THEN RA = RA + PI 370 IF IQUAD=3 THEN RA = RA + PI 380 IF IQUAD=4 THEN RA = RA + TWOPI 390 ARG = SIN(OBLIQ) * SIN(ECLLON) 400 DEC = ATN(ARG/SQR(1-ARG*ARG)): PRINT RA*12/PI,DEC/CONV

I wrote this as part of the SUNMOON program which was published with my article on calibrating antennas by observing the Sun or Moon in the ARRL UHF/VHF Handbook. It uses a formula from the "American Ephemeris and Nautical Almanac" (published by the US Navy).

If you have questions, you can e-mail me directly.

Dave W8MIF

      
Re: HP-41CX sun position program.
Message #5 Posted by Meindert Kuipers on 29 Nov 2005, 3:23 a.m.,
in response to message #1 by Michel Beaulieu

I have a Meade ETX90 and the SUN is not in the controller either, and safety is the main reason for that. The trick I know that has been used is to define a planetary object (if that is possible) that has the same orbit as the earth, but exactly opposite of the sun.

Be very very careful with solar watching. Use a good solar filter!

      
Re: HP-41CX sun position program.
Message #6 Posted by Wilhelm Loidl on 30 Nov 2005, 7:32 a.m.,
in response to message #1 by Michel Beaulieu

Hello Michel!

Something to try! I wrote this program for my 41cv.

Good luck!

Wilhelm Loidl

p.s.: sorry for the format!

LBL "SUN" FIX 04 CF 01 XEQ 07 LBL 24 XEQ 08 CLA "? GMT HR.MIN" PROMPT HR LBL 15 15 * STO 02 STO 05 RCL 03 + 365.25 / 118.1 RCL 04 968 / - + .2 P-R 9.58 - * + RCL 04 427 / RCL 04 COS - 8531.5 - 360 / CHS X<>Y -1 P-R RDN P-R R^ R-P RDN X<>Y STO 07 ASIN STO 06 RDN - ST+ 05 RCL 05 RCL 00 - RCL 06 COS P-R RCL 01 STO 06 X<>Y P-R X<> 06 RCL 07 P-R X<> 06 + ASIN X<> 06 - R-P RDN 180 + STO 08 FS? 01 RTN CLA "HRZ " ARCL X AVIEW PROMPT CLA "VRT " ARCL 06 AVIEW PROMPT GTO 24 RTN LBL 07 "LAT ?" CLA "? LAT N+ DEG" PROMPT STO 01 "? LNG W+ DEG" PROMPT STO 00 RTN LBL 08 CLA "? MM.DDYYYY" PROMPT INT STO 06 LASTX FRC 100 * INT STO 03 LASTX FRC 1 E4 * X<> Z 3056 % INT ST+ 03 R^ STO 04 RCL 06 3 X>Y? 1 RCL 04 4 / FRC + 1 X<>Y X=Y? 2 RCL 04 7 - RCL 03 365.25 / + STO 06 20 * STO 04 SIN 4 * 50941 + RCL 06 7 * + 896 / - ST- 03 360 ST* 03 RTN

            
Re: HP-41CX sun position program.
Message #7 Posted by Michel Beaulieu on 30 Nov 2005, 11:34 a.m.,
in response to message #6 by Wilhelm Loidl

Thanks for the BASIC and the HP-41 program, i'm just entering them in my 41c and my 75c.

Michel

            
Re: HP-41CX sun position program.
Message #8 Posted by Geir Isene on 30 Nov 2005, 5:02 p.m.,
in response to message #6 by Wilhelm Loidl

Like this?

001 *LBL "SUN" 
002  FIX 04
003  CF 01
004  XEQ 07 
005  LBL 24 
006  XEQ 08 
007  CLA
008  '? GMT HR.MIN' 
009  PROMPT
010  HR
011  LBL 15 
012  15
013  *
014  STO 02
015  STO 05
016  RCL 03
017  +
018  365.25
019  /
020  118.1
021  RCL 04
022  968
023  /
024  -
025  +
026  .2
027  P-R
028  9.58
029  -
030  *
031  +
032  RCL 04
033  427
034  /
035  RCL 04
036  COS
037  -
038  8531.5
039  -
040  360
041  /
042  CHS
043  X<>Y
044  -1
045  P-R
046  RDN
047  P-R
048  R^
049  R-P
050  RDN
051  X<>Y
052  STO 07
053  ASIN
054  STO 06
055  RDN
056  -
057  ST+ 05
058  RCL 05
059  RCL 00
060  -
061  RCL 06
062  COS
063  P-R
064  RCL 01
065  STO 06
066  X<>Y
067  P-R
068  X<> 06
069  RCL 07
070  P-R
071  X<> 06
072  +
073  ASIN
074  X<> 06
075  -
076  R-P
077  RDN
078  180
079  +
080  STO 08
081  FS? 01
082  RTN 
083  CLA
084  'HRZ ' 
085  ARCL X
086  AVIEW
087  PROMPT
088  CLA
089  'VRT '
090  ARCL 06
091  AVIEW
092  PROMPT
093  GTO 24 
094  RTN 
095  LBL 07 
096  'LAT ?' 
097  CLA
098  '? LAT N+ DEG' 
099  PROMPT
100  STO 01
101  '? LNG W+ DEG' 
102  PROMPT
103  STO 00
104  RTN 
105  LBL 08 
106  CLA
107  '? MM.DDYYYY' 
108  PROMPT
109  INT
110  STO 06
111  LASTX
112  FRC
113  100
114  *
115  INT
116  STO 03
117  LASTX
118  FRC
119  1 E4
120  *
121  X<> Z
122  3056
123  % 
124  INT 
125  ST+ 03
126  R^ 
127  STO 04
128  RCL 06
129  3 
130  X>Y?
131  1 
132  RCL 04
133  4 
134  / 
135  FRC
136  + 
137  1 
138  X<>Y
139  X=Y?
140  2 
141  RCL 04
142  7 
143  -
144  RCL 03 
145  365.25
146  / 
147  + 
148  STO 06
149  20 
150  * 
151  STO 04
152  SIN 
153  4 
154  * 
155  50941 
156  + 
157  RCL 06
158  7 
159  * 
160  + 
161  896 
162  / 
163  -
164  ST- 03
165  360 
166  ST* 03
167  RTN
                  
Re: HP-41CX sun position program.
Message #9 Posted by Michel Beaulieu on 30 Nov 2005, 9:02 p.m.,
in response to message #8 by Geir Isene

Thanks; with that form i was able to track my error on line 044 -1 i entered 044 - and 045 1. Now the program works great.

By the way, is there a program to convert these coordinate to equatorial one?

Thanks again Michel

      
Re: HP-41CX sun position program.
Message #10 Posted by Jean-Marc on 30 Nov 2005, 4:54 p.m.,
in response to message #1 by Michel Beaulieu

Hi, You can use the program listed in the HP-41 software library: "Astronomical Ephemeris" Regards JM

      
Re: HP-41CX sun position program.
Message #11 Posted by Norris on 2 Dec 2005, 12:31 p.m.,
in response to message #1 by Michel Beaulieu

The Sokkia company, a manufacturer of surveying equipment, publishes an annual pocket-sized "Celestial Observation Handbook & Ephemeris" for surveyors. It traditionally included professional-grade HP calculator programs for the 41, 42 and 48 series. I haven't seen the latest editions and don't know if the programs are still there; they were in the 2003 edition.

You can find this at surveying supply stores or www.forestry-suppliers.com if interested. It costs about $8.50.

The Sokkia book and programs were written by Elgin, Knowles & Senne, at http://www.rollanet.org/~eksi/softprod.htm . They apparently still offer the "Astro*Card" for HP48GX.


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