New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue #APCC


dnakic@...
 

This past Monday I was using Horizons and went to JPL Website to download Ephemeris.  I did both the text file download and the data and the format looks a bit different.  Note, the website looks different too.  The data pull would not work in Horizons.  Appreciate insight into issue.


Header format:

*******************************************************************************
 Revised: July 31, 2013             Moon / (Earth)                          301
 
 GEOPHYSICAL DATA (updated 2018-Aug-15):
  Vol. mean radius, km  = 1737.53+-0.03    Mass, x10^22 kg       =    7.349
  Radius (gravity), km  = 1738.0           Surface emissivity    =    0.92
  Radius (IAU), km      = 1737.4           GM, km^3/s^2          = 4902.800066
  Density, g/cm^3       =    3.3437        GM 1-sigma, km^3/s^2  =  +-0.0001  
  V(1,0)                =   +0.21          Surface accel., m/s^2 =    1.62
  Earth/Moon mass ratio = 81.3005690769    Farside crust. thick. = ~80 - 90 km
  Mean crustal density  = 2.97+-.07 g/cm^3 Nearside crust. thick.= 58+-8 km 
  Heat flow, Apollo 15  = 3.1+-.6 mW/m^2   Mean angular diameter = 31'05.2"
  Heat flow, Apollo 17  = 2.2+-.5 mW/m^2   Sid. rot. rate, rad/s = 0.0000026617
  Geometric Albedo      = 0.12             Mean solar day        = 29.5306 d
  Obliquity to orbit    = 6.67 deg         Orbit period          = 27.321582 d
  Semi-major axis, a    = 384400 km        Eccentricity          = 0.05490
  Mean motion, rad/s    = 2.6616995x10^-6  Inclination           = 5.145 deg
  Apsidal period        = 3231.50 d        Nodal period          = 6798.38 d
                                 Perihelion  Aphelion    Mean
  Solar Constant (W/m^2)         1414+-7     1323+-7     1368+-7
  Maximum Planetary IR (W/m^2)   1314        1226        1268
  Minimum Planetary IR (W/m^2)      5.2         5.2         5.2
********************************************************************************



Thanks,
Don

 


Ray Gralak
 

Hi Don,

 

The data from the web site just loaded okay for me. I think the default settings are a little different. See this screenshot for the settings I used. Also, it appears that you cannot use control-A followed by control-C to copy the data because the data doesn’t open up in a new window. You have to manually select and copy just the generated lines of the data.

-Ray

 

> -----Original Message-----

> From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of dnakic via groups.io

> Sent: Friday, October 1, 2021 2:48 PM

> To: main@ap-gto.groups.io

> Subject: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

>

> This past Monday I was using Horizons and went to JPL Website to download Ephemeris.  I did both the text

> file download and the data and the format looks a bit different.  Note, the website looks different too.  The

> data pull would not work in Horizons.  Appreciate insight into issue.

>

>

> Header format:

>

> *******************************************************************************

>  Revised: July 31, 2013             Moon / (Earth)                          301

>

>  GEOPHYSICAL DATA (updated 2018-Aug-15):

>   Vol. mean radius, km  = 1737.53+-0.03    Mass, x10^22 kg       =    7.349

>   Radius (gravity), km  = 1738.0           Surface emissivity    =    0.92

>   Radius (IAU), km      = 1737.4           GM, km^3/s^2          = 4902.800066

>   Density, g/cm^3       =    3.3437        GM 1-sigma, km^3/s^2  =  +-0.0001

>   V(1,0)                =   +0.21          Surface accel., m/s^2 =    1.62

>   Earth/Moon mass ratio = 81.3005690769    Farside crust. thick. = ~80 - 90 km

>   Mean crustal density  = 2.97+-.07 g/cm^3 Nearside crust. thick.= 58+-8 km

>   Heat flow, Apollo 15  = 3.1+-.6 mW/m^2   Mean angular diameter = 31'05.2"

>   Heat flow, Apollo 17  = 2.2+-.5 mW/m^2   Sid. rot. rate, rad/s = 0.0000026617

>   Geometric Albedo      = 0.12             Mean solar day        = 29.5306 d

>   Obliquity to orbit    = 6.67 deg         Orbit period          = 27.321582 d

>   Semi-major axis, a    = 384400 km        Eccentricity          = 0.05490

>   Mean motion, rad/s    = 2.6616995x10^-6  Inclination           = 5.145 deg

>   Apsidal period        = 3231.50 d        Nodal period          = 6798.38 d

>                                  Perihelion  Aphelion    Mean

>   Solar Constant (W/m^2)         1414+-7     1323+-7     1368+-7

>   Maximum Planetary IR (W/m^2)   1314        1226        1268

>   Minimum Planetary IR (W/m^2)      5.2         5.2         5.2

> ********************************************************************************

>

>

>

> Thanks,

> Don

>

>

>


dnakic@...
 

Ray, I did these steps and for some reason I'm getting the following error and cannot connect system.  I followed the steps you provided, with my inputs below.  When I selected the text, I'm highlighting all of it (top and bottom portion of text shown).  Appreciate you insight (I'm sure there is something that I did incorrectly).  Thanks!











to 




Ray Gralak
 

I can’t tell what you might have done wrong given the screenshots, but there will be an update to APCC available soon that can use the new Horizons website format.

 

-Ray

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of dnakic via groups.io
Sent: Thursday, October 14, 2021 4:11 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

 

Ray, I did these steps and for some reason I'm getting the following error and cannot connect system.  I followed the steps you provided, with my inputs below.  When I selected the text, I'm highlighting all of it (top and bottom portion of text shown).  Appreciate you insight (I'm sure there is something that I did incorrectly).  Thanks!











to 


Geert
 

I used Horizons for the first time after these changes on the JPL website and I get the same error, also the time format is 12hr off.  I hope APCC Horizons gets fixed soon :-)

Best regards,

Geert Vdbulcke

Op do 14 okt. 2021 om 13:52 schreef Ray Gralak <iogroups@...>:

I can’t tell what you might have done wrong given the screenshots, but there will be an update to APCC available soon that can use the new Horizons website format.

 

-Ray

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of dnakic via groups.io
Sent: Thursday, October 14, 2021 4:11 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

 

Ray, I did these steps and for some reason I'm getting the following error and cannot connect system.  I followed the steps you provided, with my inputs below.  When I selected the text, I'm highlighting all of it (top and bottom portion of text shown).  Appreciate you insight (I'm sure there is something that I did incorrectly).  Thanks!



Michael 'Mikey' Mangieri
 

Any word on the upcoming update to APCC to correct this?  I am setting up to capture C/2021 A1 (Leonard) and it is a fast moving comet.


fd@...
 
Edited

I am having the same problem.
I get the same error message "Apparent Alt/Elevation not found in ephemeris data".

The data IS there:

*****************************************************************************************************************************************************************************************************************************************************************
 Date__(UT)__HR:MN     R.A._____(ICRF)_____DEC  R.A.__(a-apparent)__DEC  dRA*cosD d(DEC)/dt  Azi____(a-app)___Elev  L_Ap_Sid_Time    APmag   S-brt             delta      deldot     S-O-T /r     S-T-O  Sky_motion  Sky_mot_PA  RelVel-ANG  Lun_Sky_Brt  sky_SNR
*****************************************************************************************************************************************************************************************************************************************************************
$$SOE
 2021-Nov-18 00:00 Cm  02 37 26.16 +12 30 48.6  02 38 37.76 +12 36 30.4  1720.045  820.0817   77.457834   5.983739  20 15 15.9215  -12.254   3.718  0.00269079633233  -0.2631059  165.1214 /T   14.8384   31.759023   64.509161   -14.28441         n.a.     n.a.
 2021-Nov-18 00:04 Cm  02 37 33.96 +12 31 43.5  02 38 45.57 +12 37 25.0  1711.117  820.3118   78.179302   6.602058  2
I noticed that the current header says "Azi____(a-app)___Elev"

but an old ephemerides (from 2020-11-10) uses the header "Azi_(a-appr)_Elev"

Maybe that throws HORIZONS off?

Any idea of when a new version of Horizons will be out (or ready for testing)?

+++++++++++++++++++++++++++++++++++++++

EDIT - I made it work

  • I downloaded the data from JPL. 
  • As Ray mentioned, could not CTRL-A,CTRL-C. I had to manually select and copy the ephemerides data to the clipboard.
  • I pasted the data from the clipboard into Notepad++. (Notepad also works)
  • Then on line 69 of the file I replaced "Azi____(a-app)___Elev" with "Azi_(a-appr)_Elev"  (ignore the quotes).
  • Then I saved the .txt file.
  • Horizons could read the .txt file with no errors.
  • I saved the file in Horizons, to give it the default .eph extension.
  • Success!



--
Mach1GTO and GTOCP4 on permanent pier


Ray Gralak
 

Any idea of when a new version of Horizons will be out (or ready for testing)?
I posted a beta version with a fix for Horizons about a month ago, but I haven't received any feedback for that version. In the new version, you should use the download button on the NASA Horizons website to download and load thefile into Horizons (the application):

https://ap-gto.groups.io/g/main/message/82413

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of fd@fdunlop.com
Sent: Wednesday, November 17, 2021 7:20 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

I am having the same problem.
I get the same error message "Apparent Alt/Elevation not found in ephemeris data".

The data IS there:


***********************************************************************************************************************************
******************************************************************************************************************************
Date__(UT)__HR:MN R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt
Azi____(a-app)___Elev L_Ap_Sid_Time APmag S-brt delta deldot S-O-T /r S-T-O
Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR
***********************************************************************************************************************************
******************************************************************************************************************************
$$SOE
2021-Nov-18 00:00 Cm 02 37 26.16 +12 30 48.6 02 38 37.76 +12 36 30.4 1720.045 820.0817 77.457834
5.983739 20 15 15.9215 -12.254 3.718 0.00269079633233 -0.2631059 165.1214 /T 14.8384 31.759023
64.509161 -14.28441 n.a. n.a.
2021-Nov-18 00:04 Cm 02 37 33.96 +12 31 43.5 02 38 45.57 +12 37 25.0 1711.117 820.3118 78.179302
6.602058 2
I noticed that the current header says "Azi____(a-app)___Elev"

but an old ephemerides (from 2020-11-10) uses the header "Azi_(a-appr)_Elev"

Maybe that throws HORIZONS off?

Any idea of when a new version of Horizons will be out (or ready for testing)?

--
Mach1GTO and GTOCP4 on permanent pier


Geert
 

Hi Ray,

I have used that beta a few times now. Indeed, I load the downloaded ephemeris file with the new downoad button, it works well without copying and pasting.

Thanks,

Geert Vandenbulcke
Belgium

-----Oorspronkelijk bericht-----
Van: main@ap-gto.groups.io <main@ap-gto.groups.io> Namens Ray Gralak
Verzonden: donderdag 18 november 2021 13:06
Aan: main@ap-gto.groups.io
Onderwerp: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

Any idea of when a new version of Horizons will be out (or ready for testing)?
I posted a beta version with a fix for Horizons about a month ago, but I haven't received any feedback for that version. In the new version, you should use the download button on the NASA Horizons website to download and load thefile into Horizons (the application):

https://ap-gto.groups.io/g/main/message/82413

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of fd@fdunlop.com
Sent: Wednesday, November 17, 2021 7:20 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

I am having the same problem.
I get the same error message "Apparent Alt/Elevation not found in ephemeris data".

The data IS there:


***********************************************************************************************************************************
******************************************************************************************************************************
Date__(UT)__HR:MN R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt
Azi____(a-app)___Elev L_Ap_Sid_Time APmag S-brt delta deldot S-O-T /r S-T-O
Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR
***********************************************************************************************************************************
******************************************************************************************************************************
$$SOE
2021-Nov-18 00:00 Cm 02 37 26.16 +12 30 48.6 02 38 37.76 +12 36 30.4 1720.045 820.0817 77.457834
5.983739 20 15 15.9215 -12.254 3.718 0.00269079633233 -0.2631059 165.1214 /T 14.8384 31.759023
64.509161 -14.28441 n.a. n.a.
2021-Nov-18 00:04 Cm 02 37 33.96 +12 31 43.5 02 38 45.57 +12 37 25.0 1711.117 820.3118 78.179302
6.602058 2
I noticed that the current header says "Azi____(a-app)___Elev"

but an old ephemerides (from 2020-11-10) uses the header "Azi_(a-appr)_Elev"

Maybe that throws HORIZONS off?

Any idea of when a new version of Horizons will be out (or ready for testing)?

--
Mach1GTO and GTOCP4 on permanent pier






This email has been scanned by BullGuard antivirus protection.
For more info visit www.bullguard.com


Ray Gralak
 

Hi Geert,

Okay, thanks for confirming the Horizon update in the beta works!

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Geert
Sent: Thursday, November 18, 2021 5:14 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

Hi Ray,

I have used that beta a few times now. Indeed, I load the downloaded ephemeris file with the new downoad
button, it works well without copying and pasting.

Thanks,

Geert Vandenbulcke
Belgium

-----Oorspronkelijk bericht-----
Van: main@ap-gto.groups.io <main@ap-gto.groups.io> Namens Ray Gralak
Verzonden: donderdag 18 november 2021 13:06
Aan: main@ap-gto.groups.io
Onderwerp: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

Any idea of when a new version of Horizons will be out (or ready for testing)?
I posted a beta version with a fix for Horizons about a month ago, but I haven't received any feedback for that
version. In the new version, you should use the download button on the NASA Horizons website to download
and load thefile into Horizons (the application):

https://ap-gto.groups.io/g/main/message/82413

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of fd@fdunlop.com
Sent: Wednesday, November 17, 2021 7:20 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

I am having the same problem.
I get the same error message "Apparent Alt/Elevation not found in ephemeris data".

The data IS there:


***********************************************************************************************************************************
******************************************************************************************************************************
Date__(UT)__HR:MN R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt
Azi____(a-app)___Elev L_Ap_Sid_Time APmag S-brt delta deldot S-O-T /r S-T-O
Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR
***********************************************************************************************************************************
******************************************************************************************************************************
$$SOE
2021-Nov-18 00:00 Cm 02 37 26.16 +12 30 48.6 02 38 37.76 +12 36 30.4 1720.045 820.0817 77.457834
5.983739 20 15 15.9215 -12.254 3.718 0.00269079633233 -0.2631059 165.1214 /T 14.8384 31.759023
64.509161 -14.28441 n.a. n.a.
2021-Nov-18 00:04 Cm 02 37 33.96 +12 31 43.5 02 38 45.57 +12 37 25.0 1711.117 820.3118 78.179302
6.602058 2
I noticed that the current header says "Azi____(a-app)___Elev"

but an old ephemerides (from 2020-11-10) uses the header "Azi_(a-appr)_Elev"

Maybe that throws HORIZONS off?

Any idea of when a new version of Horizons will be out (or ready for testing)?

--
Mach1GTO and GTOCP4 on permanent pier






This email has been scanned by BullGuard antivirus protection.
For more info visit www.bullguard.com





Michael 'Mikey' Mangieri
 

Yes - thanks Ray and Geert. I was out last night at 3:30-5:30 AM tracking down comet Leonard, but didn't try to use Horizons at that time. Later this weekend I'll give it a go.

-Mikey

-----Original Message-----
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Ray Gralak
Sent: Thursday, November 18, 2021 8:28 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue

Hi Geert,

Okay, thanks for confirming the Horizon update in the beta works!

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf
Of Geert
Sent: Thursday, November 18, 2021 5:14 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC -
Format Causes Issue

Hi Ray,

I have used that beta a few times now. Indeed, I load the downloaded
ephemeris file with the new downoad button, it works well without copying and pasting.

Thanks,

Geert Vandenbulcke
Belgium

-----Oorspronkelijk bericht-----
Van: main@ap-gto.groups.io <main@ap-gto.groups.io> Namens Ray Gralak
Verzonden: donderdag 18 november 2021 13:06
Aan: main@ap-gto.groups.io
Onderwerp: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC -
Format Causes Issue

Any idea of when a new version of Horizons will be out (or ready for testing)?
I posted a beta version with a fix for Horizons about a month ago, but
I haven't received any feedback for that version. In the new version,
you should use the download button on the NASA Horizons website to download and load thefile into Horizons (the application):

https://ap-gto.groups.io/g/main/message/82413

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf
Of fd@fdunlop.com
Sent: Wednesday, November 17, 2021 7:20 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] New JPL Format for Horizons Ephemeris #APCC -
Format Causes Issue

I am having the same problem.
I get the same error message "Apparent Alt/Elevation not found in ephemeris data".

The data IS there:


**********************************************************************
*************************************************************
******************************************************************************************************************************
Date__(UT)__HR:MN R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt
Azi____(a-app)___Elev L_Ap_Sid_Time APmag S-brt delta deldot S-O-T /r S-T-O
Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR
**********************************************************************
*************************************************************
********************************************************************
**********************************************************
$$SOE
2021-Nov-18 00:00 Cm 02 37 26.16 +12 30 48.6 02 38 37.76 +12 36 30.4 1720.045 820.0817 77.457834
5.983739 20 15 15.9215 -12.254 3.718 0.00269079633233 -0.2631059 165.1214 /T 14.8384 31.759023
64.509161 -14.28441 n.a. n.a.
2021-Nov-18 00:04 Cm 02 37 33.96 +12 31 43.5 02 38 45.57 +12 37 25.0 1711.117 820.3118 78.179302
6.602058 2
I noticed that the current header says "Azi____(a-app)___Elev"

but an old ephemerides (from 2020-11-10) uses the header "Azi_(a-appr)_Elev"

Maybe that throws HORIZONS off?

Any idea of when a new version of Horizons will be out (or ready for testing)?

--
Mach1GTO and GTOCP4 on permanent pier






This email has been scanned by BullGuard antivirus protection.
For more info visit www.bullguard.com





Michael 'Mikey' Mangieri
 

Well, after some trial and error I finally got Horizons to work using the beta release of APCC and the instructions given by Ray to change the header text.  But now I have an interesting question ...
In testing out this feature I decided to target Ceres since it was placed high in the sky during the early evening hours. I wanted to test out the horizons tracking for comet Leonard but it doesn't rise above my tree line until 2:30-3:00 in the morning.  I ran the JPL ephemeris for Ceres and loaded it into APCC.  All went well. I then set my mount (AP1100) to track Ceres starting at 10:30pm.  When the mount slewed to Ceres it was not at the correct location according to Stelarium which I use to target objects and control the mount's initial slew. The location given by Stellarium is RA:  04h 23m 37.6s;  DEC:  +16d 45m 16.2s.  But the JPL data is giving  RA: 04h 22m 57.7s;  DEC:  +16d 39m 30.4s.  This is a considerable discrepancy. APCC Horizons thus points the telescope to a location well out of the FOV of the camera.  
Not sure this is the proper place to discuss this, but has anyone experienced this issue?  This makes setting up a planned tracking impossible since the coordinates are not correct.  I've checked my location (Lat/Lon), and the settings on all the software and they are correct. J2000 vs 'on date' may contribute some of the error, but not nearly the amount I'm seeing.


 

Two things come to mind

First is to make sure you solve and recal ahead of time so your pointing is is as accurate as possible

Second is Comet/satellite tracking is very sensitive to accurate time, many people (myself included) invest in a gps system with realtime clock updates using something like NMEATime



On Fri, Nov 19, 2021 at 8:25 PM Michael 'Mikey' Mangieri <mjmangieri@...> wrote:
Well, after some trial and error I finally got Horizons to work using the beta release of APCC and the instructions given by Ray to change the header text.  But now I have an interesting question ...
In testing out this feature I decided to target Ceres since it was placed high in the sky during the early evening hours. I wanted to test out the horizons tracking for comet Leonard but it doesn't rise above my tree line until 2:30-3:00 in the morning.  I ran the JPL ephemeris for Ceres and loaded it into APCC.  All went well. I then set my mount (AP1100) to track Ceres starting at 10:30pm.  When the mount slewed to Ceres it was not at the correct location according to Stelarium which I use to target objects and control the mount's initial slew. The location given by Stellarium is RA:  04h 23m 37.6s;  DEC:  +16d 45m 16.2s.  But the JPL data is giving  RA: 04h 22m 57.7s;  DEC:  +16d 39m 30.4s.  This is a considerable discrepancy. APCC Horizons thus points the telescope to a location well out of the FOV of the camera.  
Not sure this is the proper place to discuss this, but has anyone experienced this issue?  This makes setting up a planned tracking impossible since the coordinates are not correct.  I've checked my location (Lat/Lon), and the settings on all the software and they are correct. J2000 vs 'on date' may contribute some of the error, but not nearly the amount I'm seeing.



--
Brian 



Brian Valente


Michael 'Mikey' Mangieri
 

Thanks for the insight. I had verified both and they are OK. What I did find is that the problem is with Stellarium. A photo of where Ceres should be according to Stellarium didn’t show the dwarf planet. When I slewed to the coordinates given by JPL she was in the field; not perfect but well within the FOV. So now I guess it’s time to contact the Stellarium folks. Maybe the Solar System plug-in isn’t all that accurate for asteroids and comets. 


On Nov 20, 2021, at 1:27 AM, Brian Valente <bvalente@...> wrote:


Two things come to mind

First is to make sure you solve and recal ahead of time so your pointing is is as accurate as possible

Second is Comet/satellite tracking is very sensitive to accurate time, many people (myself included) invest in a gps system with realtime clock updates using something like NMEATime



On Fri, Nov 19, 2021 at 8:25 PM Michael 'Mikey' Mangieri <mjmangieri@...> wrote:
Well, after some trial and error I finally got Horizons to work using the beta release of APCC and the instructions given by Ray to change the header text.  But now I have an interesting question ...
In testing out this feature I decided to target Ceres since it was placed high in the sky during the early evening hours. I wanted to test out the horizons tracking for comet Leonard but it doesn't rise above my tree line until 2:30-3:00 in the morning.  I ran the JPL ephemeris for Ceres and loaded it into APCC.  All went well. I then set my mount (AP1100) to track Ceres starting at 10:30pm.  When the mount slewed to Ceres it was not at the correct location according to Stelarium which I use to target objects and control the mount's initial slew. The location given by Stellarium is RA:  04h 23m 37.6s;  DEC:  +16d 45m 16.2s.  But the JPL data is giving  RA: 04h 22m 57.7s;  DEC:  +16d 39m 30.4s.  This is a considerable discrepancy. APCC Horizons thus points the telescope to a location well out of the FOV of the camera.  
Not sure this is the proper place to discuss this, but has anyone experienced this issue?  This makes setting up a planned tracking impossible since the coordinates are not correct.  I've checked my location (Lat/Lon), and the settings on all the software and they are correct. J2000 vs 'on date' may contribute some of the error, but not nearly the amount I'm seeing.



--
Brian 



Brian Valente


dnakic@...
 

Sorry for not responding earlier.  I had great success.  I copied the data when the ephemeris is generated in its entirety.   Also, you can do the “download results” and Select All (cntrl A) and Copy (cntrl C).  Either way, the beta worked very well and thanks!  This software is so essential for imaging solar system objects … great work Ray.