G'day all,
There has been a fair amount of discussion about the EQ6's goto capabilities that often has degenerated into a discussion about PEC....a horse of a different colour.
My own experience with the EQ6 suggests that if it is well polar aligned it performs 'gotos' well. By way of example the recent EP view of ngc3532 I posted was the result of an initial 1 star alignment check on Sirius then a 'goto' ngc 3532. There was a minor position adjustment to put a suitable guide star onto the webcam guider chip and that was all.
Later, I tried to locate a star that is not included in the EQ6 library by using the 'show position' function and driving to the required RA and DEC co-ordinates. Not there!! I then performed a 1 star alignment on Spica which is only a few degrees from my required target; still not there. I downloaded a DSS image of the target co-ordinates and the star in question dead centered in the image. The co-ordinates are not wrong, the polar alignment is correct.....
Spica was centered as best I could judge without the luxury of cross hairs on the lappy screen. The date, time, Lat and logitude settings are correct.
I tried again a few nights later when I got a clear sky only to pull up the same star field...the wrong star field.
If I'm doing something wrong, I can't for the life of me think what it could be.
The scope is balanced fairly well, any tight spots in the drive don't interfere with normal goto operation, so I'm wondering if anyone else might have encountered a similar problem or can see an obvious error in my procedure. The target co-ordinates are, RA 13h 44'46.6" and Dec -14:13:30
The attached image is a DSS plate download 60'x60'
Hi Doug,
I have found that you need to do at least 2 star align if you are working in the close area of the 2 stars(i.e. S,E,N,W, if not, 3 star align gives the handset/mount a better idea of the complete coverage area.
If I do a 2 star south align, most things N,NW,NE are out slightly.
3 Star improves that again.
Hope this helps
G'day Adrian. I haven't had time + clear skies to mess around with a 3 star alignment yet. I still don't believe I should need to but will try anything to get to the bottom of this issue. The attached screen shot shows 3 focus images of 5 seconds each.
The top image is Hadar as it falls when selected for a 1 star alignment. That is to say that what this shows is the pointing accuracy from park position after I have entered date/time and selected Hadar for a 1 star alignment routine.
Below left is Hadar after I have centered it. Actually it is a bit off center, but close enough. Bottom right is a 5 sec focus shot of Omega centauri without any adjustment after a goto. As you can see the Mount's pointing accuracy is quite satisfactory when I use the built in data base to goto a target. I tried to do a forth shot of Centaurus A because that involved a meridian flip, but high cloud + fullish moon beat me. Still Centaurus A was on the frame but shifted a little to one side of center. The problem still remains that using the hand controller to move to a non data base object seems to fail. Tonight I tried a new target, (hence Aligning on Hadar instead of Spica), but again the target seems not to be there. Tonight was not a good night to be trying to match faint star fields, but my mount is well polar aligned, that is why I am so mystified at not finding non database objects. The other intriguing thing is that after finding Omega Centauri, I used the H/C to manually go back to Hadar's RA and Dec and found that it was still back in center frame. I can't blame the H/C, entirely, but maybe it in some way compares with the data bases or else the other night was a red herring. I need some good clear nights to really get to the bottom of this.
Thanks for your input, I will try a three star when/if we get clear skies,
Doug, for astrophotography you will need to make the effort for a 3 star alignment. It improves accuracy to an amazing level. And the 3 star alignment gets rid of 'Cone Error' too.
Doug, for astrophotography you will need to make the effort for a 3 star alignment. It improves accuracy to an amazing level. And the 3 star alignment gets rid of 'Cone Error' too.
Mornin Ken, if I could see the SCP I would get most of the cone error adjusted out of the mount mechanically, but still, if I were imaging over Meridian flip cycle I would need to 3 star align anyway, granted.
My non data base target tonight was at RA 15:21:48.15 Dec -48:19:03.5. As you can see the distance from Hadar is less than Omega's distance from Hagar. Surely if the mount with a 1 star align can move from Hadar to Omega with the accuracy shown in the screen shot, it should find a target that is even closer.
Or, to put it another way, how would a 3 star alignment allow the mount to locate an object only 16d 26' 28" from Hadar (as the celestial crow flies) when a 1 star alignment can not, yet will allow the mount to faithfully locate an object 19d 10' 48" from that same Hadar, almost 3d further away?
My query is not about the relative merits of the different alignment methods, but rather abiout the apparent discrepency between a data base orchestrated goto and a manual goto operation.
Using The SKY Atlas I can do an image link with an image of mine of M42, and also a dss plate of the target areas, so I think it fair to say that The Sky software is reliable. I can not get an 'image link' with the field I am imaging.
That is the problem.
I don't know much about the EQ6 goto but have a SS2000 on my mount.
Can you make the EQ6 talk to planetarium software like skymap pro?
If so have you tried to make the scope slew to the star using the planetarium software. This will confirm if the accuracy of the goto is not to blame but how the data is being entered.
G'day Terry, that's a worthwhile thought!
I can connect the EQ6 to 'The Sky' software. The only problem there is that (and I can't remember exact details) there is a discrepancy of several degrees between where the scope finishes up pointing and where 'The Sky' reports it to be, or where I want it to go. I guess that sounds weird, but that is what I thought too, when I tried it. Since the problem was not too easy of resolution, and I tend not to hop all over the sky in any one evening, I never bothered pursuing it. All I can remember is that it was not due to daylight savings time /sidereal time differences. Now that you have brought that issue to the surface I think I should investigate it further as there may well be a connection.
Thanks Terry,
cheers,
Doug
Hi Guys,
Yes, great idea to connect software.
Doug, do you have v 3.12?
If so, have you tried PAE "Pointing Area Enhancement"?
There is a PAE function in the GOTO that enhances GOTO in small areas of the sky.
When on a nearby target, go into "setup" & choose PAE.
This will refine the local area search.
Hope it helps
G'Day Adrian, not sure what version I have; think it could be v3.10. I know I have an update to do but I have not yet done so. It will be interesting to see if it fixws a few anomolous things for me see following reply.
cheers,
Doug
G'day Terry, Bingo!! After a 1 star alignment, I connected 'The Sky' and moved to the required co-ordinates and it dead centered the star I was interested in see first image.(probably a different field from the first DSS plate I posted). I then went to visit A-Centauri, again dead centered it, yet 'The Sky' screen shows the error I mentioned previously. I know this error does not occur when I'm using the Meade classic LX200, and also if I input co-ordinates the Meade goes to the correct location too. There must be some 'funny' in the hand controller that causes the pointing error when info is being read from the 'display'.
I guess I should upgrade the firmware to v3.12 and see if that makes a change.
Meantime thanks for your input and fresh approach.
G'day Terry, Bingo!! After a 1 star alignment, I connected 'The Sky' and moved to the required co-ordinates and it dead centered the star I was interested in see first image.(probably a different field from the first DSS plate I posted). I then went to visit A-Centauri, again dead centered it, yet 'The Sky' screen shows the error I mentioned previously. I know this error does not occur when I'm using the Meade classic LX200, and also if I input co-ordinates the Meade goes to the correct location too. There must be some 'funny' in the hand controller that causes the pointing error when info is being read from the 'display'.
I guess I should upgrade the firmware to v3.12 and see if that makes a change.
Meantime thanks for your input and fresh approach.
