How to schedule an iTelescope for multiple objects?

[PMSchu]

Hi Greg,

I'm not sure if this question belongs here or in the iTelescope Forum, feel free to move it.

I'm trying to get up to speed on using the iTelescope system in preparation for an upcoming tutorial with Dr. Sasse next week. For starters I wanted to do astrometry on 2 main belt asteroids (10482) Dangrieser and (10483) Tomburns using iTelescope T05 in New Mexico. I created Imaging projects for each object as shown below:

When I ran the ST4i Scheduler, there was a gap between the observations of the 2 asteroids, so I decided to add some exposures of Comet 46P/Wirtanen to fill the gap. The Imaging Project for Wirtanen is shown below:

As the comet is very bright I tried to limit the exposures to 15 min/filter, but I messed up the exposure time for the blue filter and the Scheduler produced this Plan for T05: (Looks like I can't control where the attachment files appear in the post - this will probably get confusing  sorry.)

Question 1: Why did the Scheduler schedule Wirtanen 3 times? Given the brightness, 15 min/filter should have been plenty of exposure. 2 minutes should have provided SNR's in the hundreds for each color and 1000+ for the Clr filter. I didn't select the Astrometry option for the comet, but I did for each asteroid. This added 2 hrs to the plan's run time.

Question 2: If I strip out the extra Wirtanen imaging runs would the plan work properly or will the times for Tomburns be incorrect? Except for the extra Wirtanen images and the error I made on the blue filter this is close to what I wanted to accomplish.

When I tried to schedule Dangrieser only I got this plan: The dither command is included, but I don't see the explicit dithering commands for RA & Dec as in the plan for all 3 objects.

I fixed the error with the blue filter & got this plan as a result: Both asteroids are dithered, but there are still 3 series of exposures on Wirtanen.

It looks like I can't add more attachments. I add a second post with additional attachments after you have a chance to digest this one. Let me know if you have questions about what I'm trying to do. Maybe I'm asking too much of the Scheduler & should simplify what I'm doing.

Also, how do I remove an Imaging Project from the Scheduler's consideration? It now has 3 objects and I can't remove Wirtanen to schedule just the 2 asteroids. I must be missing something.

TIA,

Phil S.

[theskyhound]

Hello,

I hope you had little trouble finding this thread after I moved it. I am also hoping this isn't a bug, but if it is I will fix it ASAP. I am close to another update.

In order to understand what is happening I need to know what you did to schedule 46P. So you had a gap between the observations. What exactly did you do to add 46P? Also, it would be best if you could send screen captures of the Scheduler as follows:

1. Before adding 46P
2. With the 46P project selected on the left but not yet added
3. After adding 46P

Thanks!
Greg

[theskyhound]

Regarding Question 2: I think you are asking about leaving a gap in the plan? That won't work with iTelescope, unless the gap is very short. The way this is handled for private observatories is to simply wait until the time to start the next observation, but this is frowned upon by iTelescope, so the presumption is that the plan will run with no gaps. You should get a message about this if you create a plan with gaps in it... did you see that?

Regarding removing imaging projects, are you using the automated scheduling, e.g. the Schedule button? If so, what you can do is right-click in the project line under the column marked "S" (status). Select Exclude. This will place an "X" in the column and the auto-scheduler will ignore the project when scheduling.

Sending Scheduler screen captures will be much more useful to me because there is no much more information present. I should also be able to start reproducing what you are seeing too, which will really help me figure out what is going on.

Thanks,
Greg

[PMSchu]

Hi Greg,

I didn't have a problem finding the moved thread. I've been working at scheduling for over a week, but this is the first time I tried to run the Scheduler for an iTelescope. When I started it was several days ago & the moon was still new. For the first attempts I used one of my personal Imaging Systems so the iTelescope restrictions didn't apply. My IS's are pure manual control.

The screen-shots of the Scheduler are attached as requested:

I knew that iTelescope doesn't allow gaps >5 min. That's why I tried to add Wirtanen to fill the gap. The Scheduler allotted much more time to Wirtanen than I expected. The message about gaps did appear when I tried to Save the plan. I clicked the Compact button as instructed to remove the time gaps. I've tried both the 'Auto Schedule' and 'Add' buttons for scheduling.

This scheduling result is not what I got earlier. The Scheduler made no attempt to put any Wirtanen images in the space between the Dangrieser & Tomburns images as I'd hoped.

Is there a way to send my Imaging Programs so you can see what I've done wrong? Dangrieser is starting to make the turn back to normal motion (i. e. not retrograde, prograde motion?)

Let me know if you want more information.

TIA,

Phil S.

[theskyhound]

Hello Phil,

There have been several issues reported with regard to 46P. This is the first bright comet since the Scheduler was born, and there seem to be some problems. I am currently working on these issues now.

I missed it the first time, but I just noticed that something is wrong with the 46P imaging project. The exposure table shows dashes in the column that normally displays the expected time required to reach the target SNR. A dash means that it was unable to reach the target SNR (which seems unlikely) or the calculation didn't work for some other reason. I suspect that whatever caused this is also the root cause of the problem you had with the Scheduler. I'll look at the code and do some experimenting in the morning, but I suspect it comes about because you forced the exposure time to be 60 seconds, but that is too long. Either the signal clips (goes past 65000 ADU) or saturates the detector.

I will look into this in detail in the morning. I suspect what may be needed is some tests for this sort of failure and error/warning message to inform the user of what is happening.

I will also post an example of how I would go about scheduling for iTelescope that you may find useful.

[theskyhound]

Hello Phil,

In many ways scheduling for iTelescope is simpler than for a private system because so much, like calibrations, is done for you. But in one way it is more complex: because we are sharing the system, we need to iterate a bit, starting with a target object and figuring out when it is best to observe it on a specific night, checking to see if that time is available on the telescope, and if so, making a reservation. Once the reservation is made, then we constrain the Scheduler to the time period matching our reservation.

Here are some tips regarding scheduling for iTelescope:

1. Once a reservation is made, set the time period on the Scheduler to match the reservation. You can do this by dragging the vertical lines on the Nightbar or by entering the start and end times directly in the "From" and "to" fields. Once the time period set, use the Auto Schedule button to fill it out.

2. If there is a gap in the schedule, set the time period to be the start and end times of gap. Then schedule for the gap. This will keep the Scheduler from filling another time slot.

3. For iTelescope I often prefer to manually schedule. To do this, I select one project at a time and schedule it by right-clicking on it and selecting Schedule Project (or just double-clicking on it). This allows me some control over the order, while at the same time taking advantage of the Scheduler to make smart choices for this like filter order and sub exposure times. When doing this it is important to use the information available to help decide which project to schedule when. The graphic below the Nightbar is very useful for this.

4. Sometimes I discover that I want to change the minimum exposure quality (Min. Q) on the fly. You don't need to open the imaging project to do this. You cna right-click in the Min. Q. column to change the value quickly.

5. When I know that the iTelescope has a lot of open time available, sometimes I set only the start time and leave the end time all the way to the right. Then I schedule each object one at a time, building toward later in the night. When I am happy with it, I note the time that my schedule ends and use that to make my reservation.

6. If you are willing to work weeks or even months ahead of time, the iTelescope schedule is often uncluttered or even empty.

7. Sometimes I "poach" observing time by scheduling in real time. I watch what is going on live. Sometimes people don't show up for their reservation. Other times an error occurs. The time then becomes available. People also often schedule too much time for the project, leaving the telescope idle when their plan finishes. When I see this sort of thing happening, I set the Scheduler to start at the current time (or when I think time will become available), quickly generate a plan, upload it, and when the iTelescope becomes available I start my plan.

There was a night a few months ago when a new comet discovery was made and I wanted to get an observation from Australia just before dawn. But all of the iTelescopes were in use. So I created an imaging project for every iTelescope that was appropriate for astrometry, uploaded them, and waited. The moment one because available I jumped in and started the plan.

Clear skies,
Greg

[PMSchu]

Hi Greg,


I've noticed that 46P has been problematic due to its brightness. I did see the dashes in the 46P Imaging Project, but it didn't register that there would be problems. Note to self: 'Dashes = future problems with the Imaging Project', eliminate them at this stage. The Exposure Calculator doesn't like 46P either. Many times the EC's 'Calculate SNR for Exposure' section reports 'Aborted' for 46P. For T05 tonight the EC estimates SNR=1000 for a 60 sec exposure. The estimated signal is 67e^6 ADU!! That looks a bit excessive  . I know that exposures can be <60 sec for the iTelescopes, but they warn about the effects of camera read-out time. I'll talk with Dr. Sasse about this during my tutorial on Monday (14 Jan 2019). What are the problems associated with uncalibrated exposures, if any, for simple LRGB imaging? If they're negligible, I could drop the exposure time into the 1-5 sec range.

From your previous post I can see that there are a lot of capabilities of ST4i that I'm not using effectively/properly. I need to reread TFM now that I understand more of what's going on. Especially regarding the Scheduler which I glossed over.

The idea of scheduling scope time weeks in advance is totally foreign to this Ohio boy! The weather around Columbus is some of the worst in the country for clouds. OSU didn't move the Perkins 69" scope to Flagstaff for nothing  .

The iTelescopes require a 4 hr notice for making/breaking reservations. This is another subject for Dr. Sasse.


The steps that you listed in your previous post are very helpful. I did notice that the position of the right-click in the Scheduler make a big difference. I should have examined all of the columns to see what happens. I still don't see how I can remove an Imaging Project from the Scheduler window. I know it's Imaging System dependent, but I can envision the window filling up with old Imaging Projects that I can't remove unless I delete the project itself. Just putting an x in the S column still leaves the project on the list. Again, maybe I've missed something in the instructions.

Thanks again for all your help, I'm making progress,

Phil S.

P. S. This forum requires approval of a moderator for my posts to appear, unlike the actual SkyTools forums. Good to have activity in the other forums though.

[PMSchu]

Hi Greg,

I forgot to put the question mark at the end of the subject line of my OP. I don't know if you can add it after-the-fact, but it makes more sense with the question mark .

Phil S.

[PMSchu]

Hi Greg,

I took another stab at the Scheduler this morning. I reduced the exposure time to 1 min/filter and set a max exposure of 5 sec for Wirtenen. I also changed the mode from SNR to Exposure Time on the top left of the Exposure Goals tab. The 'Equ. Exp.' in the 'Filters' area still reads '--'. The moon is now interfering with Dangrieser and tonight will be the last shot for a while. Last night the weather had all of the northern hemisphere  iTelescopes out of action - Spain due to ice despite the cloudless night . I remember observing in the winter with my Odyssey 1 dob and having frost on the tube. No electronics to mess up on that scope though .

I scheduled each object individually and the Scheduler provided the schedule attached:

After scheduling all 3 objects the Scheduler looks like this:

The Scheduler didn't perform the 3 observations requested for astrometry for either asteroid. It did do that for some of the schedule runs a few days ago, maybe there's not enough time to fit them in or the objects aren't moving fast enough.

What is involved in the calibration process, since iTelescope doesn't have calibration data for 5 sec exposures? Are these the darks, flats and bias frames that the image processing programs use?

The schedule looks like it could be used in its present form, so I think I'm much further along in this process. Thanks for your help,

Phil S.

[theskyhound]

Hi Phil,

I have been looking into 46P and I have found a bug. When you create an imaging project for a comet, the "Expose for..." setting on the Exposure Goals tab is not initializing properly. The second selection that defaults to "main coma, tail" is not actually initialized correctly internally. The work around is to manually make this selection for your projects, even if it is to re-select the default.

I have also found an unforeseen problem related to such a bright comet. This problem can affect the accuracy of the exposure results, not only for the Imaging Project exposure table, but elsewhere. The fix is complicated. I am currently working on it and hope to have an update soon.

Regarding calibration, it depends somewhat on the iTelescope, but normally there are two choices:

1) iTelescope will apply the closest calibration (60 seconds) and you can just use that. This works fine for most cameras.

2) You may need to make your own master dark image at 5 seconds, and do the calibration yourself. You can have the system take a lot of darks during twilight or daylight and use them to create the master. Use the flat fields already provided, as it is only the darks that may need to be at the same exposure time.

BTW it is a erroneous setting that is requiring post approval for this forum. I am going to fix it, once I find the setting again. ;-)