multi session imaging query

[Subaru19]

Would like to pick the brains on imaging the same deep sky object over several sessions- days or weeks, please. 

I attempted imaging the whirlpool galaxy last night during the brief 2 hour window of cloudless sky last night and was really pleased with the result, but obviously i need more exposure time to make the image better. My question is how do i get to the exact same field of view the next time? i am guessing that alignment and stacking will not work, if the frames are not centred relative to each other. Heard of something about plate solving software, but will these work in my set up-  heq5 mount controlled by ST4 cable going from guidescope to the mount ( and usb cable from guidescope to laptop)  Can't control the mount directly from my laptop. Any advice would be helpful. Thanks

[Atreta]

Yes, it will work the way you want. You can use apt( it's the one i use) to handle the imaging session and to platesolve and slew to a previous target.

There is a pinned post right on this forum teaching how to setup platesolving with apt. 

Edit: also you can have the target roughly in the same position manually and the stacking program will align it,   make sure that it's not much far from the previous image. 

Edited July 15, 2019 by Atreta

[carastro]

You don't need to plate solve, I do this quite regularly without.   The secret is to orientate the camera the same each time, or as close as you can get it.  Then try to position the target as close as possible to the last imaging session, which may require an image to hand from last time.  Look at the stars around the edges to try to get them in the same place.

APT has a routine for matching images to a previous session, though I never got it to work very successfully. 

OK, Plate solving might be quicker if you can use it, but I manage just fine.

Stacking software will handle this just fine, but if you have dismantled the camera from the scope since last session, you will need a new set of flats and then the stacks will have to be done separately.

If you are using DSS there is a routine for stacking separate sessions.  Otherwise I just stack each session and then stack the stacks.

N.B. If you don;t have your camera orientated in the scope exactly the same as previously there could be a bit of rotation which will result in you having the crop the edges.

Quote

plate solving software, but will these work in my set up-  heq5 mount controlled by ST4 cable going from guidescope to the mount ( and usb cable from guidescope to laptop) 

Yes you can set up plate solving with the HEQ5, you would need an EQDir cable to control the mount from the laptop, and various software to make EQMOd work.  Then to make platesolving work you need a whole heap more of software.  Unless you are really confident with IT stuff I'd give it a miss. 

HTH.

Carole 

Edited July 15, 2019 by carastro

[Subaru19]

thank you both for the prompt and very helpful response. the sky is reported to be clear tonight as well. will give it a go, manually as you had suggested, Carole. but would definitely try out apt if i have enough time tonight, or if not for future sessions. Thanks Atreta.

[carastro]

Yes, setting up EQMOd and platesolving is not something that can be done in a hurry.

Carole 

[Tommohawk]

24 minutes ago, carastro said:

You don't need to plate solve, I do this quite regularly without.   The secret is to orientate the camera the same each time, or as close as you can get it.  Then try to position the target as close as possible to the last imaging session, which may require an image to hand from last time.  Look at the stars around the edges to try to get them in the same place.

Yep, agree with this. Have done lots of multi-session image stacking and don't know the first thing about plate solving. If you leave the camera /scope assembled between runs then the orientation will be the same - if not just try and align the camera much as it was previously. Centre the image so its similar to before and DSS will take care of the rest, rotating and aligning as required.

 

[Subaru19]

39 minutes ago, carastro said:

You don't need to plate solve, I do this quite regularly without.   The secret is to orientate the camera the same each time, or as close as you can get it.  Then try to position the target as close as possible to the last imaging session, which may require an image to hand from last time.  Look at the stars around the edges to try to get them in the same place.

APT has a routine for matching images to a previous session, though I never got it to work very successfully. 

OK, Plate solving might be quicker if you can use it, but I manage just fine.

Stacking software will handle this just fine, but if you have dismantled the camera from the scope since last session, you will need a new set of flats and then the stacks will have to be done separately.

If you are using DSS there is a routine for stacking separate sessions.  Otherwise I just stack each session and then stack the stacks.

N.B. If you don;t have your camera orientated in the scope exactly the same as previously there could be a bit of rotation which will result in you having the crop the edges.

Yes you can set up plate solving with the HEQ5, you would need an EQDir cable to control the mount from the laptop, and various software to make EQMOd work.  Then to make platesolving work you need a whole heap more of software.  Unless you are really confident with IT stuff I'd give it a miss. 

HTH.

Carole 

Thanks, i did have a feeling that you needed special cable and not just st4 . thanks for clarifying it. Cheers

[Starwiz]

I've just been through the special cable / plate solving learning curve myself after a few years of imaging with the ST4 cable connected from guide camera to mount.

It's well worth doing it.  No more searching for faint nebula that doesn't seem to show up where you expect it - just plate solve which tells software exactly where the mount is pointing, then tell it to go find the coordinates you want.

John

[Atreta]

1 hour ago, Subaru19 said:

Thanks, i did have a feeling that you needed special cable and not just st4 . thanks for clarifying it. Cheers

You can control it using only the st4 cable connected to the guide camera and the mount and the usb from the camera to the laptop.

Give it a a go since you already have it.  We can help you out if you have any difficulties with it. 

Edited July 15, 2019 by Atreta

[Subaru19]

Thanks everyone for the advice and encouragement. Got almost the same field of view back ( manually)comparing with the image from the previous night.  Autoguiding was a bit of a problem, working flawlessly for about 10 minutes and then there would be a big deviation, anyway that's a different issue. and then there was the near full moon. Havent stacked the images yet to see how well i have done, but I am much more optimistic with multi session imaging now. will keep you all updated. Thanks for your help!.

13 hours ago, carastro said:

You don't need to plate solve, I do this quite regularly without.   The secret is to orientate the camera the same each time, or as close as you can get it.  Then try to position the target as close as possible to the last imaging session, which may require an image to hand from last time.  Look at the stars around the edges to try to get them in the same place.

APT has a routine for matching images to a previous session, though I never got it to work very successfully. 

OK, Plate solving might be quicker if you can use it, but I manage just fine.

Stacking software will handle this just fine, but if you have dismantled the camera from the scope since last session, you will need a new set of flats and then the stacks will have to be done separately.

If you are using DSS there is a routine for stacking separate sessions.  Otherwise I just stack each session and then stack the stacks.

N.B. If you don;t have your camera orientated in the scope exactly the same as previously there could be a bit of rotation which will result in you having the crop the edges.

Yes you can set up plate solving with the HEQ5, you would need an EQDir cable to control the mount from the laptop, and various software to make EQMOd work.  Then to make platesolving work you need a whole heap more of software.  Unless you are really confident with IT stuff I'd give it a miss. 

HTH.

Carole 

Thanks, i did have a feeling that you needed special cable and not just st4 . thanks for clarifying it. Cheers

[ollypenrice]

I'm always bemused by the way plate solving seems to have become 'essential' when, like Carole, I still don't use it.

Carole says to orientate the camera as closely as possible to its original position. This is true, but the trick is to orientate the chip along the lines of RA and Dec, either in landscape (long side along RA) or portrait (long side along Dec.) This is dead easy to do: do it by eye first of all, sighting the camera so it's parallel with the dovetail. Refine it by taking a 5 second sub while slewing slowly in just one axis. This will produce a star trail at some angle to the chip. Repeat while rotating the camera between subs till the star trail is parallel with the edge of the chip and you're done. It is very rare indeed for framing to require any other angle and, by sticking to RA and Dec, repeatability is easy to achieve. Just look at the stars around the edges of the image.

Olly

Edited July 16, 2019 by ollypenrice

[spillage]

Whilst I agree to some extent that relying on software to do the work for can at times cause more issues than it solves I do think using platesolving was a pinnacle moment for me. It means that I can just load up a previous image or choose a new target and let the thing get on with it. Normally within a few minutes I am on target ready to start imaging leaving me more time to try and sort out the other problems I have. 

@ollypenrice I can only dream of owning kit like a mesu but I guess with all the star mapping and permanent set up your mount will take you to a target from a list of targets and be very precise without really needing to platesolve. With something like the neq6 or kit you need to set up every night  things can be a bit more difficult and time consuming.

[Starwiz]

1 hour ago, ollypenrice said:

I'm always bemused by the way plate solving seems to have become 'essential' when, like Carole, I still don't use it.

Not essential, and I managed for three years without it.  But it is another useful tool in the astro-toolkit.

I have to assemble and disassemble for each imaging session, so it makes it a little easier, rather than trying to find exactly where I want to image which may be different than the coordinates given for a specific object.  Once I have decided the coordinates for the image, I can input them into APT as a custom object, so it makes imaging the same place on different nights much easier for me.

I remember last year trying to find 'the wall' in NGC7000.  I'd told the scope to go to this object which sent it somewhere in the centre of NGC7000, but  I didn't have a clue from the first image which direction 'the wall' would be in.  In the event, I went the wrong way looking for it and must have wasted about 40 minutes or more before I found it and was happy with the framing.

Having said that, it was quite a learning curve getting all the software installed, then getting it working, but I found it quite satisfying when it finally did. 😀

[ollypenrice]

3 hours ago, Starwiz said:

  Once I have decided the coordinates for the image, I can input them into APT as a custom object, so it makes imaging the same place on different nights much easier for me.

 

I write mine down on a piece of paper. (While I prefer a quill pen I'll stoop to a biro if nothing else is to hand!)

lly

(I can never remember how to set up user defined objects or how to find them in the handset if I do . )

 

Edited July 16, 2019 by ollypenrice

[Starwiz]

20 minutes ago, ollypenrice said:

(I can never remember how to set up user defined objects or how to find them in the handset if I do . )

I've ditched the handset, so the mount's controlled from the laptop via Cartes Du Ceil and APT, also using ASCOM and EQMOD plus PHD2.

In APT for instance, I've defined NGC7000 The Wall as a custom object.  I can then use the APT Point Craft feature to plate solve which works out where the scope is actually pointed, and then sync with CdC after which I just go to the object.  After reaching the object, Point Craft plate solves again to check, then does another move and solve if needed.

John

 

[ollypenrice]

3 hours ago, Starwiz said:

I've ditched the handset, so the mount's controlled from the laptop via Cartes Du Ceil and APT, also using ASCOM and EQMOD plus PHD2.

In APT for instance, I've defined NGC7000 The Wall as a custom object.  I can then use the APT Point Craft feature to plate solve which works out where the scope is actually pointed, and then sync with CdC after which I just go to the object.  After reaching the object, Point Craft plate solves again to check, then does another move and solve if needed.

John

 

I like handsets. They are not on the internet and no update for WIndows 10 will ever kill them. (They can kill the camera and the filterwheel - and have done so - but the mount is internet free.)  As a provider I'm in a slightly different position from most people since this kind of setback is not an interruption to my hobby, it's a let-down for our guests so I really don't want it to happen.

Olly

[Starwiz]

8 minutes ago, ollypenrice said:

They are not on the internet and no update for WIndows 10 will ever kill them. (They can kill the camera and the filterwheel - and have done so

That's a little concerning.  I wasn't aware - do you have any more info?

John

[ollypenrice]

10 hours ago, Starwiz said:

That's a little concerning.  I wasn't aware - do you have any more info?

John

Every now and then an update upsets the functioning of certain devices. From memory, a couple of years ago an internal change to the Windows time clock clashed with the timekeeping of the SiTech mount control system as used on some up market mounts including Plane Wave and Mesu. More recently a Win 10 update clashed with Atik camera software at just the same time as Atik were snowed out of their factory, so delaying their response. Both issues were fixed but it's just an example of why, if I can keep an item computer-free, I do so. (A good few years ago I reconfigured a PC for dual screens and this trashed my camera control. I think this was a Vista bug. The better you are with IT the less seriously these will disable you but I'm not an IT expert.) Again, it's particularly important for me as a provider to have stuff that works. At one time I had a Takahashi mount (not recommended) which could only be PC controlled and, despite religiously using the same USB port, I lived in fear of the message 'Device not recognized' when I powered it up for the evening. Sometimes it would just do this, quite randomly so far as I could see. I still get connection issues with filterwheels on occasion and, quite honestly, would happily go back to a manual one for the narrowband half of our dual rig where we never want to scroll filters.

Olly

Edited July 17, 2019 by ollypenrice
Typo

[carastro]

Quote

(I can never remember how to set up user defined objects or how to find them in the handset if I do . )

I use the Synscan User Defined Object on the handset when the target is not in the synscan catalogue, i.e. a VBN or Sh2 target.  But annoyingly Skywatcher Synscan does not let you name the target, or record and save more than 1 at a time.  So I have to re-input every time I change targets, including any I have done at an earlier occasion but have since done another user object.  Rather annoying I find.   I also have to remember which target is recorded as all it will give you is the coordinates.  

Olly, it's in the menu where you select named star, then scroll down until you find user object.  Middle button 8 if I recall without looking at the handset. 

While I am on this subject.  I do find it a chore sometimes to find the actual coordinates of some targets - any-one got a good resource for this?  I find myself scouring the internet hoping some-one has recorded it, often its in Wikipedia, but sometimes not.  Am now keeping my own list of these targets that I have done so far and when I remember post them up when I actually image the target on my website so I have a permanent record, and also maybe it might help others.

Carole  

Edited July 17, 2019 by carastro

[ollypenrice]

2 hours ago, carastro said:

I use the Synscan User Defined Object on the handset when the target is not in the synscan catalogue, i.e. a VBN or Sh2 target.  But annoyingly Skywatcher Synscan does not let you name the target, or record and save more than 1 at a time.  So I have to re-input every time I change targets, including any I have done at an earlier occasion but have since done another user object.  Rather annoying I find.   I also have to remember which target is recorded as all it will give you is the coordinates.  

Olly, it's in the menu where you select named star, then scroll down until you find user object.  Middle button 8 if I recall without looking at the handset. 

While I am on this subject.  I do find it a chore sometimes to find the actual coordinates of some targets - any-one got a good resource for this?  I find myself scouring the internet hoping some-one has recorded it, often its in Wikipedia, but sometimes not.  Am now keeping my own list of these targets that I have done so far and when I remember post them up when I actually image the target on my website so I have a permanent record, and also maybe it might help others.

Carole  

The RA and Dec co-ordinates are usually on the net if you look the object up but what I prefer to do is model the framing in my planetarium software and note the centre of that frame as I intend to image it. Once actually framing up the target outside I'll note (on good old paper) my final choice of co-ordinates. I then just have RA and Dec showing on the handset another night and slew to the target while looking at those co-ordinates as they roll past. It's so easy that I've never felt the need to change it.

Olly

[carastro]

The joys of having a permanently set up rig though Olly.  I am only permanently set up in the winter when I have Bortle 8 skies.  

Carole 

[spillage]

@carastro are you using APT as you are able to download additional targets to your custom list or you can just open the file (mine opens in my browser) and then search for targets using the ctrl + f to find.

[carastro]

Quote

@carastro are you using APT as you are able to download additional targets to your custom list or you can just open the file (mine opens in my browser) and then search for targets using the ctrl + f to find.

No, I have APT but prefer to use Artemis it's much better for live view/looping so you can see what you are doing.

Carole 

[Starwiz]

5 hours ago, ollypenrice said:

Every now and then an update upsets the functioning of certain devices. From memory, a couple of years ago an internal change to the Windows time clock clashed with the timekeeping of the SiTech mount control system as used on some up market mounts including Plane Wave and Mesu. More recently a Win 10 update clashed with Atik camera software at just the same time as Atik were snowed out of their factory, so delaying their response. Both issues were fixed but it's just an example of why, if I can keep an item computer-free, I do so. (A good few years ago I reconfigured a PC for dual screens and this trashed my camera control. I think this was a Vista bug. The better you are with IT the less seriously these will disable you but I'm not an IT expert.) Again, it's particularly important for me as a provider to have stuff that works. At one time I had a Takahashi mount (not recommended) which could only be PC controlled and, despite religiously using the same USB port, I lived in fear of the message 'Device not recognized' when I powered it up for the evening. Sometimes it would just do this, quite randomly so far as I could see. I still get connection issues with filterwheels on occasion and, quite honestly, would happily go back to a manual one for the narrowband half of our dual rig where we never want to scroll filters.

Olly

I know only too well what a problem updates can be, but have never experienced them causing hardware faults.  When I was working, several of our machines had to be disabled from receiving updates due to the software problems and loss of production they caused.

One solution would be to have a dedicated computer for imaging with the updates disabled.  Then once configured, you could disconnect from the internet (I disconnect anyway before imaging so I don't get any unwanted interference).

But nothing wrong with using a handset if you're happy with the process.

John

[Starwiz]

13 minutes ago, carastro said:

No, I have APT but prefer to use Artemis it's much better for live view/looping so you can see what you are doing.

Carole 

The Histograms tool in APT allows you to auto-stretch the image.

I've found this really useful after going from a DSLR to the ASI1600mm-Pro.  With the latter not stretched, all I can see are a few stars in the image and even less when on live view.

The images shown are of the same Ha sub, with and without the APT auto-stretch applied.

John