Dusk/Dawn/SkyFlat problems with computer clock set to Universal Time (UT)

Hi Leonardo,

I have been using Voyager’s SklyFlat sequence and Dragscript “Wait for Dusk/Dawn” to obtain twilight flats. It works great and I routinely get great results.

I have encountered some problems recently as the time of dusk approaches 6PM here in Colorado (0h UT).

For instance – here is an error from just 2 nights ago when I had SkyFlat sequence running.

00:07:36 214 - INFO - [SkyFlat] - [CHECK_Code] - Check Voyager Environment
00:07:36 214 - INFO - [SkyFlat] - [CHECK_Code] - Flat Type is Sky at Dusk
00:07:36 434 - INFO - [SkyFlat] - [InitEngineDusk] - Dusk and Dawn Engine Initialized
00:07:36 434 - EVENTO- [SkyFlat] - [InitEngineDusk] - Dusk Event @ 23:58:00
00:07:36 480 - INFO - [SkyFlat] - [RestoreEnvironment] - Mount Tracking Restored to Tracking
00:07:36 480 - INFO - [SkyFlat] - [RestoreEnvironment] - Camera ROI Reset to Default
00:07:36 480 - INFO - [SKYFLAT_ACQUISITION ] - [Funzione] - Action Time [SKYFLAT_ACQUISITION] => 0 [m] 0 [s]
00:07:36 480 - INFO - [SKYFLAT_ACQUISITION ] - [Funzione] - Action Time Mobile Mean [SKYFLAT_ACQUISITION] => 23 [m] 9 [s]
00:07:36 495 - WARNING - [DragScript Run ] - [VOY_FLAT_WAIT_Code] - ERROR (FINISHED) Flat : Bad Conditions : Dusk event not reached

Just 2 days ago, local dusk occurred at 5:59 PM local time (23:59 UT), this seems to be causing Wait for Dusk and Dusk SkyFlat to fail.

I believe it is because I use Universal Time on the clock of my control computer. (This is a great advantage in planning, coordination with my scientific program, and the ability to ignore local time almost entirely.)

It seems Voyager may be reading the clock and thinks that it is midnight?

If you agree that this is the problem, I was thinking about how a change to Voyager would allow me to use UT and still use the Dusk/Dawn Dragscript functions and SkyFlat sequences. If these had a field called “UT Offset”, then it could be added to the clock by Voyager when doing this calculation. For instance, in Colorado, that number would be -6 (at present). Voyager would read 0h from the clock, add -6h t0 get 18:00 which would be the correct local time.

Is this a modification that you would consider making?

Many thanks,

Ed Beshore

Dear Ed,

please use localtime on your PC if you want to use Voyager features !

We use UTC for targeting in Voyager Advanced (One Shot and Time Interval mode) but not for flat that will not have sense because all the times are calculated automatically internally by Voyager.

All the best
Leonardo Orazi

Hi Leo - I appreciate your reluctance to make lots of changes to Voyager.

As a retired astronomer, I would just say that we use UT for everything, converting only to local time when necessary.

Local time creates many opportunities for errors and problems.

Kind regards,


Sorry Ed but what create problem is the target interval time if used in local time mode, all the other things are automatically managed. So my suggestion is to evaluate the Voyager Advanced version that use for this kind of task the UTC time. I hope this helps.

All the best