When the nudge/minimal guiding gets activated is it based on exceeding a minimum movement or do you use some other parameter on which the guiding nudge occurs?
That is strictly up to what maximum error you don't want to exceed. In my case that was 0.3 arcseconds, which is set in the guider software as a Min Move setting of .02 seconds. Any guide star movement less than that, there are no guide pulses sent to the mount. Anything above that, guide pulses are sent according to the aggressiveness setting, which in my case was set at 50%.
Rolando
-----Original Message-----
From: Khushrow Machhi via groups.io <kmachhi@...>
To: main@ap-ug.groups.io
Cc: kmachhi@... <kmachhi@...>; main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Thu, Aug 27, 2020 3:44 pm
Subject: Re: [ap-gto] [ap-ug] Pillars of M16
When the nudge/minimal guiding gets activated is it based on exceeding a minimum movement or do you use some other parameter on which the guiding nudge occurs?
The image is beautiful, especially with the pollution but also with how close the moon is to M16.
Khushrow
On Aug 27, 2020, at 12:43 PM, Roland Christen via groups.io <chris1011@...> wrote:
Not unguided but modeled and nudge guided. By that I mean that the mount runs on a sky model which produces a custom rate that adjusts the RA and Dec tracking to what is needed to counter the atmospheric refraction, plus a minimal guiding. I use a Lodestar off-axis guider set for 10 second exposures and let the guider nudge the mount every once in a while to keep it on track.
Drift is complex when imaging close to the horizon and the tracking rate changes from minute to minute as the mount moves Westward and the object begins sinking into the southern horizon. You can get a simple model to work well for 5, 10 or even 15 minutes, but long 1 hour exposures are not going to work when imaging at or near 1 arc sec per pixel image scale.
In my second image, which was taken from several hours past the meridian, the guide star drifted 15 arc seconds in both axes due to atmospheric refraction in that 1 hour time frame.
Rolando
-----Original Message-----
From: Khushrow Machhi via groups.io <kmachhi@...>
To: main@ap-ug.groups.io
Cc: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Thu, Aug 27, 2020 2:18 pm
Subject: Re: [ap-gto] [ap-ug] Pillars of M16
Is the 1hr sub unguided with the Mach2?
Khushrow
On Aug 27, 2020, at 11:17 AM, Roland Christen via groups.io <chris1011@...> wrote:
Hi Astronuts,
The recent M16 image that Ignacio posted presented me with a challenge to see what could be achieved here in Northern Illinois, using a 160EDF refractor. Challenge indeed it was. The object is only about 30 degrees above the horizon, directly over a huge mall and auto dealer complex, the Moon was quite nearby. Seeing down near the horizon is quite iffy in the best of nights. Plus, we still have smoke in the skies from out west. temperature was in the mid-80's so my camera would not cool down to below about -15C.
Even though i was shooting thru a narrowband H-a filter, I didn't know what to expect. On top of that I decided to go for broke and do 1 hour subs, two of them were combined in the images I just posted:
