? After many years of owning Obsession telescope & ServoCATs, it wasn't too late to make dumb mistakes. The Alt cable on my 22" UC came out of the groove when I was moving the telescope minus the truss tubes & UTA a few feet to a more level ground (I neglected to secure the mirror assembly to the ground board before moving it with the wheelbarrow handles).

Hi Bernhard,

With the ServoCAT protocol, Argo Navis transmits and expects object coordinates as ICRS and airless.

Sky Safari should do the same and the last time I tested it, it appeared to be doing that correctly. Perhaps it has changed.

Whether they both happen to internally do the transformations to/from catalog mean place to observed place then matters not.

Part of the babble in coordinate spaces between planetarium programs and amateur telescopes historically came about from the fact that legacy DSC's and telescope controllers did not perform the transformations from catalog to observed and back. In other words, they didn't do the transformations for precession, nutation, refraction, etc. A classic example of this are the early Meade computerized telescopes and the Sky Commander DSC. There were limitations in their hardware, such as not supporting time of day clocks and limitations in their software, in not supporting observed place to catalog place and back transformations. To make matters worse, different planetarium programs would make assumptions about what coordinate space these devices were sending o expecting and sometimes writers would get it wrong.

Argo Navis was named a Digital Telescope Computer (DTC) rather than Digital Setting Circles (DSC) in direct acknowledgement that DSC's, like their mechanical counterparts, did not perform the additional transformations.

Going forward I would encourage all software practitioners to transmit and expect positions as catalog mean ICRS and airless.

Planetarium programs should purge out of date notions such as JNow.

On another note, I don't know if it changed but I recollect ASCOM use to have two separate commands for fetching RA and fetching Dec. There should have been a single command that fetch both. They are coordinates and go hand-in-hand like peas in a pod.

One thing to note when interfacing with planetarium programs is the finite resolution of the encoders. One test is to dial up MODE ALIGN STAR and align on a star. At that very instant Argo Navis aligns to the catalog position and when a program such as Sky Safari requests the position at that instant, you should see the cross-hairs very nearly on the star. With the progression of time, Argo Navis will keep updating the position the scope is pointing to on the assumption it is not tracking. If in fact it is tracking. when it sees the next encoder step the computer position will go back to the original alignment star. For example, a 10,000 step encoder has a resolution of around 2.1 arc seconds a step. So their is a radius of uncertainty corresponding to that. This is normal.

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Hi Garry and other particpiants?

sorry for involving me.
You mentioned Argo Navis supports precession and notation (and takes perhaps further corrections).
The SkySafari program also allows some adjustments concerning these corrections.
Even though I do a correct Argo Navis alignment? the cursor in SkySafari differs a bit from object position on display.
I wonder If it is not productive to make double adjustments in both programs and if this even perhaps worsens the pointing accuracy.
Which adjustments suggest you to do in the SkySafari program??

best regards
Bernhard

开云体育

One thing we/I should check is if I'm doing the math right for adjusting the coordinates for a sync operation. One surefire way to tell would be whether the coordinates report the synced coordinates immediately after a sync. Can you tell if that happened here?

I wasn't able to test this feature in the field, and relied on simulators. We had a particularly bad stretch of weather when I implemented this.

Thanks all for your response. I am relaying this info to George Helios who is developing the new Servocat driver

Mike

Hi Mike,

For the ServoCAT protocol, Argo Navis expects and transmits coordinates in terms of ICRS (International Celestial Reference System) and expects them to be airless.

ICRS was adopted by the IAU by resolution in the years 2000 and with it J2000 came to an end.

From the year 2000 onwards, the IAU declared all position coordinates are with respect ICRS. There never will be a J2050.

From a practical viewpoint and to answer your question use J2000. The reference frames upon which J2000 and its replacement, ICRS, are within milliarcseconds of each other.

However, software writers should over time deprecate the use of the term J2000 and use the term ICRS.

Argo Navis internally supports precession and notation and will internally transform the RA/d conversions to/from catalog mean place to/from intermediate place.

It also supports refraction correction and will internally transform the RA/d coordinates to/from intermediate place to observed place.

In other words, there is never a use for so-called "JNow".

Though the differences between J2000 and ICRS from a practical viewpoint with respect what we are discussion here are essentially zero, rather than be pedantic, I am attempting to alert the amateur astronomy community that the terms J2000 and JNow, etc. should be regraded as dead and buried, having passed away on 1 Jan 2000. Start saying "ICRS" :)

https://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2008ASPC..394..179W&defaultprint=YES&filetype=.pdf

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I would think that does not matter what argo uses because it is told an RA,DEC or equivalent position to go to.? But I don't know really.? Just spouting off. Sorry.

I have been using George Hilios's new Servocat ASCOM driver which works much better with Sharpcap Pro to Plate solve and move the scope. One problem though is that when using Sharpcap's plate solve and re-center feature, the scope goes in the wrong direction and actually moves further away from the target than it was originally as seen in Cartes du Ciel. I verified that the platesolve itself works excellent but something else is amiss. I am starting to think it could be differences in what epoch is being used between the ASCOM driver, Cartes du Ciel and servocat/Argo Navis. George's driver I think defaults to JNow but can be switched to J2000. I suspect that Servocat only moves x degrees based on what Argo tells it so is not really part of the equation. Does anyone know if Argo Navis uses JNow or if it uses J2000?

Mike

Mike,

I've responded to both your emails ... the 2nd response, because it was obvious you didn't get the first, was sent out using a different email address. please check your spam folder.?

Gary Myers
StellarCAT

Hi Mike,

Firstly check the LED on the ServoCAT labelled DSC.

When you first interface Argo Navis and ServoCAT and power the two on, that DSC LED should begin blinking.
The two units have an initial little chit chat with each other and the ServoCAT then blinks the DSC LED to denote that communication
between the two is successful.

After a completed successful star alignment, the DSC LED should go steady ON.

Argo Navis has two serial ports, SERIAL 1 and SERIAL 2. Double check that the cable is plugged into the correct serial port.
Verify that you are using the correct cable to interface between the two. Whilst there are other cables that look similar, they will
almost certainly be wired differently and not work.
Since Argo Navis has two serial ports, you could also configure the "other" port to have a STARTUP of navis and a BAUD rate of 19200,
power the unit OFF, move the cable to the "other" port and then see whether the ServoCAT DSC LED flashes.

Email us if you require further assistance.

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For reason I cannot correct, AN will not connect to ServoCAT. ? All was working well until the connection failed the next time I used my OTA. ?AN is functioning normally. ?After the usual startup protocol and a 2 star alignment, the encoders are functioning normally guiding me as I “push to” my target. ?Also when I power on the hand control, the function buttons all are working normally when I engage the ALT/AZ motor drives. ?What I don’t hear is the series of 3 double beeps after I power-up and turn on AN to indicate the 2 units have made connection. ?In AN under settings/SERIAL I have the correct parameters: SERIAL 1, BAUD rate, and ServoCAT. ?I have read through the manual but have not found anything that I have missed or not engaged correctly. ?It occurs whether I power by lithium battery or use the AC adapter for power. ?Again it was working fine until it failed and I cannot think of anything that may have happened. ?Any suggestions on what the problem may be? ?

There should be ASCOM logs in "Documents\ASCOM" separated by day. If you go into the ServoCAT driver settings, enable all of the log options and try again - there should be a few ASCOM files to help debug this.

Just read Paul's saga and realised the issues I am having are pretty much the same as his.

Even though the utility says the version is 70.C it incorrectly reports all other parameters. Didn't see a resolution to this.

Reading Paul's topic it seems he only got it to work what AN was connected to the DSC port on the SC. I don't understand how this helps as the PC running the planetarium program is not connected to the AN but the USB port on the SC. George mentions the AN has to be set to Planetarium program before he got it to work. Since the Planetarium program is connected to the SC and not the AN I do not understand how this helps.

I guess I probably need help from George to make any progress.

Ian B

I have upgraded Servocat to latest v7 version (from Gary) but still cannot get NINA or Stellarium to connect to the Servocat.

I am also using George's latest v7 ASCOM driver and latest version of ASCOM core software.

In NINA it starts to connect, pauses a few seconds, and then a red box comes up asking me to reconnect the telescope. There are no .Net errors in the windows application log (there were before I updated the Ascom platform and latest ASCOM Servocat driver). It tells me to look in "Inner Log" - don't know where that is or if it would help.

In Stellarium the attempt to connect to the mount through Ascom just sits in the 'connecting' state - for ever. I removed the old direct to ArgoNavis option just in case it was interfering.

I used to control the mount through ArgoNavis connection to Stellarium (for which there is a non Ascom option) but wish to move away from ArgoNavis being in the equation.

Any help would be appreciated.

Regards

Ian B

Hi Gary,

Thanks for the directions. ?AN and SC have been great additions to my very durable 15” Obsession. ?With those additions I now have a telescope on steroids - I should add the stalk made by Charles Stark has made these additions “plug and play”. ?For example, 2 nights ago after my 2 star alignment of Polaris and Altair using a cross hair eyepiece to minimize pointing errors, and linking to SkySafari on my iPAD, for the next 2 hours I slewed to about 10 targets in several constellations all of which were in the FOV only requiring minimal adjusting to center the target. ?Finding a target under urban skies when a limited number of stars are visible from which to star hop to your target is truly a luxury.

Mike