Date
1 - 15 of 15
New JPL Format for Horizons Ephemeris #APCC - Format Causes Issue #APCC
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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.
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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
********************************************************************************
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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 > > >
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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 
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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!
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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@...>:
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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.
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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 2I 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
-- Mach1GTO and GTOCP4 on permanent pier
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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-----
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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----- This email has been scanned by BullGuard antivirus protection. For more info visit www.bullguard.com
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Ray Gralak
Hi Geert,
toggle quoted messageShow quoted text
Okay, thanks for confirming the Horizon update in the beta works! -Ray
-----Original Message-----
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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.
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-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-----
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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.
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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 ... --
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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.
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On Nov 20, 2021, at 1:27 AM, Brian Valente <bvalente@...> wrote:
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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.
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