PIER-05 Moon Down

Steve,
When I started out on this pier I received some data completely comprised by strong moonlight. I believe that you advised I needed to put some moonlight restrictions in the comments box.
Now I don't really know how the scheduling software works e.g. what weights to the various observing conditions; cloud, zd, moon phase etc., is it fully automated or is there some human intervention?

Without this detailed knowledge, I have tended to err on the conservative side by requesting moon down or < 25%.    My thinking is as follows.  This is an OSC camera, and most DSO imaging will be impacted by the moon.  An image is only as good as its weakest band - for am OSC thesis the B filter in the Bayer matrix.  As a professional, I always used the dictum that the time to call it quits with sky brightness was when the sky counts were doubled over a dark sky.  For B band this occurs at roughly Day 5 moon, or around 25%. Hence framing my request as moon down or < 25%. 

If we were to use this approach, then 10 nights per lunation fulfil that criterion and a further 8 or so nights still have moon down for an average 50% of time - giving approximately 14nights per lunation - approximately half the time.   I am not sure this is what you mean by "only so many days per month", but it doesn't look to back to me.

Ideally it would be helpful to frame the request as "please only take the image when the sky brightness is fainter than 21mag/arcsec", but again I am not sure if the scheduling software has the ability to interpret this.  

So, in the absence of better information, my request will still request moon down or <25%, which allow me to use the telescope on half the lunation while getting as good data as possible. 

Steve,
When I started out on this pier I received some data completely comprised by strong moonlight. I believe that you advised I needed to put some moonlight restrictions in the comments box.
Now I don't really know how the scheduling software works e.g. what weights to the various observing conditions; cloud, zd, moon phase etc., is it fully automated or is there some human intervention?

Without this detailed knowledge, I have tended to err on the conservative side by requesting moon down or < 25%.    My thinking is as follows.  This is an OSC camera, and most DSO imaging will be impacted by the moon.  An image is only as good as its weakest band - for am OSC thesis the B filter in the Bayer matrix.  As a professional, I always used the dictum that the time to call it quits with sky brightness was when the sky counts were doubled over a dark sky.  For B band this occurs at roughly Day 5 moon, or around 25%. Hence framing my request as moon down or < 25%. 

If we were to use this approach, then 10 nights per lunation fulfil that criterion and a further 8 or so nights still have moon down for an average 50% of time - giving approximately 14nights per lunation - approximately half the time.   I am not sure this is what you mean by "only so many days per month", but it doesn't look to back to me.

Ideally it would be helpful to frame the request as "please only take the image when the sky brightness is fainter than 21mag/arcsec", but again I am not sure if the scheduling software has the ability to interpret this.  

So, in the absence of better information, my request will still request moon down or <25%, which allow me to use the telescope on half the lunation while getting as good data as possible. 

Merry Xmas Brian

Yeah, moon down for some dim objects in conjunction with other normal objects being used with standard moon avoidance parameters can be a very productive way of using the pier

I was just letting members know in case they were unaware the vast majority seem to be moon down of late and this could impact data collection, especially during unsettled weather periods that may fall over new moon for instance. This could mean little data collection

PS the automated moon avoidance parameters are at the top of the lounge as a sticky . We cannot do specials like <25% etc as our system does not allow it

https://www.roboscopes.com/index.php/forum/pier-5-objects-to-image-6/862-moon-avoidence-settings

Cheers

Steve

https://www.roboscopes.com/media/kunena/attachments/824/120-5moon.png

Hi Steve,

And a Happy New Year to you!

I was aware of that sticky note, but I  must admit to being somewhat skeptical of those moon avoidance settings.  It has been my experience that, as soon as a bright moon (e.g. more than 7 days old) is in the sky, most of the sky is flooded with ilight, irrespective of distance from the moon.  However, that s only my experience,  coupled with a few scientific papers on night-sky brightness at certain locations.

Nevertheless, I am sure that these curves must be based on empirical or modelled data based on the Roboscopes site.  Given that some thought/modeeling must have gone into these curves, what max increase in sky brightness do these curves actually correspond to?  Also I was a little confused by the "120 & 5" condition applied to each avoidance settings.  I get the 120deg min separation at full moon, but wasn't sure what the &5 refrerred to (also the width 5) bar on each chart.  Also what it the yellow line on each chart? 

I wasn't aware that the system couldn't interpret <25% moon.  Rather can it interpret limit of days post/pre new Moon?  For those of us who are more adverse to having a brighter moon in the sky for broadband/OSC, this would appear to be a safer way to extend the imaging period.  If the & 5 refers to avoidance  in day around full moon, then it would appear the software could also taken into account a Boolean contract around "moon down or  >7 days from full moon".   Could the scheduling software be adapted?  

Thanks

Brian

Hi Steve,

And a Happy New Year to you!

I was aware of that sticky note, but I  must admit to being somewhat skeptical of those moon avoidance settings.  It has been my experience that, as soon as a bright moon (e.g. more than 7 days old) is in the sky, most of the sky is flooded with ilight, irrespective of distance from the moon.  However, that s only my experience,  coupled with a few scientific papers on night-sky brightness at certain locations.

Nevertheless, I am sure that these curves must be based on empirical or modelled data based on the Roboscopes site.  Given that some thought/modeeling must have gone into these curves, what max increase in sky brightness do these curves actually correspond to?  Also I was a little confused by the "120 & 5" condition applied to each avoidance settings.  I get the 120deg min separation at full moon, but wasn't sure what the &5 refrerred to (also the width 5) bar on each chart.  Also what it the yellow line on each chart? 

I wasn't aware that the system couldn't interpret <25% moon.  Rather can it interpret limit of days post/pre new Moon?  For those of us who are more adverse to having a brighter moon in the sky for broadband/OSC, this would appear to be a safer way to extend the imaging period.  If the & 5 refers to avoidance  in day around full moon, then it would appear the software could also taken into account a Boolean contract around "moon down or  >7 days from full moon".   Could the scheduling software be adapted?  

Thanks

Brian

Morning Brian

The settings are based on the Lorentzian moon avoidance system, so the smaller the phase the closer you can image to the moon. It works well on the whole but as ever nothing is perfect apart from imaging Moon down so yes you still have to compromise.

120 is just a little less than we use for luminance as OSC is less affected on the whole, that's also the reason for the number 5, it creates a sharper bell curve that allows much closer imaging while the moon is in its smaller phases. we use a 7 for luminance so it will have a shallower curve and always image further away even with small moon phases.

We could just image moon down but I am sure members would then be unhappy with the productivity of the pier, so as with most things in life we have to compromise. Depending how it goes we may yet tweak the numbers but we are not sure yet

Honestly Brian, the moon avoidance works well as is and none of us have the time for such a major code rewrite at the moment

PS ignore the yellow dots, its just an effect

HTH

Steve

Thanks Steve. The penny has finally dropped. You are using the BAIT moon avoidance function. That explains a lot.

i am glad it works for you.