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Calculating times for time-series photometry - david.odriscoll - 2019-05-07

Hi Greg and all
I have been using ST for some time now, largely to plan a double star programme I have been involved in.  The capabilities it provides are unique in comparison to other planning software I have used.
However I am now turning my attention to my real passion, eclipsing binaries.
It has taken me a while to understand the complexities of the exposure planning and scheduling process, but I think I have it all sorted now.  However I wonder if I am misunderstanding the process, or if I have discovered an "opportunity for improvement".   Smile
Say that that the EB has a time of minima of 2:30am.  I want to do a time-series set of as many images as I can at 60 second per exposure for a duration of 4 hours (which gives me 2 hours either side of the eclipse to capture the shoulders of the light curve).
However when planning the project, if I specify 4 hours of total imaging time, I actually get an imaging run for much longer than that, given read times etc.  That makes perfect sense, but plays havoc when I am trying to do the scheduling if I have expected to start and finish at a particular time.  It tends to result in an iterative process to work out how much "total exposure time" can be achieved during the nominated time window.
Is there some feature of the planning process that I am missing that would assist with this?
Alternatively, it would be good to provide a third option on the exposure planning window - total exposure duration, which would calculate the number of exposures based on the available imaging window.
I am open to all ideas.

RE: Calculating times for time-series photometry - theskyhound - 2019-05-07

Hello David,

If you look on the Exposure Goals tab of the Imaging Project Dialog there is a Photometry selection, but it is disabled. This is a feature I was working on implementing, but was having trouble getting it to work properly, and none of the Beta testers were apparently doing photometry. Now that someone has indicated that they want it, I will start working on it again.

In the meantime, there are probably workarounds, but I need to know how you control your imaging system, e.g. ACP, ACP Scheduler, Real Time Imaging, etc.

RE: Calculating times for time-series photometry - david.odriscoll - 2019-05-11

Hi Greg

ah!  I had wondered about that panel on the Exspoure window.  Well then, sign me up for your testing program! Big Grin  I'm keen to help.

I am currently using two robotic scopes: iTelescopes and a private system for a high school using ACP Expert, but for that one I simply generate a plan and load it up remotely - not as sophisticated as iTelescopes but effectively the same approach.

For me, the optimal requirements look like this:
1. Nominate the time of the event (mid-eclipse/ToM - time of minima)
2. Nominate a duration before/after event over which to do the photometry - for EBs, this would generally be identical, but for other targets the two durations might be different
3. Nominate the exposure time and filter - but see note below

The system would then determine the number of images able to be taken during that time (given other delay factors) and generate a plan something like this:

; Plan Generated via SkyTools 4 Imaging
; Start observation on 2019 May 9 at 00:20 local time ending 03:50 local time
#count 210
#interval 60
#binning 1
#filter V
YY Aps 15.042863 -72.753017
; Total exposure time 12600 s 210.0 min 3.5000 hr

Note that all this is assuming I am doing single filter (typically V) time-series imaging, focusing on the ToM - for this I am looking at high-cadence imaging (and will probably turn off any periodic focusing as well).  But some targets might need to support multiple filter time-series runs (and hence a lower cadence for each filter).  For this the plan would look like this I think:

#repeat 40
#count 1,1,1,1,1
#interval 120,90,60,60,90
#binning 1,1,1,1,1
#filter U,B,V,R,I
YY Aps 15.042863 -72.753017

I haven't gotten to the stage of doing this, so that may not be the best way.  But the exposures for each filter might be different I think.

A somewhat rambling response, so my apologies, but hopefully that helps.

RE: Calculating times for time-series photometry - theskyhound - 2019-05-13

Thanks David,

I will look at it and get back to you when i have a question or something to test.


RE: Calculating times for time-series photometry - david.odriscoll - 2019-05-14

Thanks Greg.

RE: Calculating times for time-series photometry - gakellerman - 2019-07-07

Is there any update to developing the Photometry settings?

RE: Calculating times for time-series photometry - theskyhound - 2019-07-08

(2019-07-07, 10:04 PM)gakellerman Wrote: Is there any update to developing the Photometry settings?

Not yet.