jimjam11

Looks like it could be pinched optics to me. Raise it with WO and they will help you diagnose if this is indeed the case. I had the same and flo sent me a replacement which was far better.

What imaging camera are you using? Your RA RMS is approx 2x your dec so that could lead to non-round stars, your PA might actually be too good?

Eqmod has an AutoPec feature. Get everything setup and start guiding on a target, start autopec and it will do everything for you.

Likewise, I havent found eqmod pec helpful vs straight guiding using the PPEC algorithm.

Clear sky is a rare beast so I have spent a decent amount of time studying my imaging efficiency and trying to improve it. I want to get as much acquisition time as possible per clear dark hour but I wonder if I am alone in pursuing this? Products like SGPro make automation relatively easy but in my experience this automation can easily lead to poor efficiency especially if you are using a cmos camera which works best with shorter exposures. When I first got my ASI1600 and used it with SGPro I measured my interframe delay to be approximately 16s. Combined with 30s L subs that equated to a wastage of circa 50% meaning each hour would yield on 30mins of data. With 60s RGB subs it was slightly better but still leading to a wastage of around 27%. Studying the SGPro logs I noted the following: I had image history turned on, this added approx 5s per frame and SGPro did not perform this analysis asynchronously. Despite my CEM60 only having a USB2 hub, image download was taking 2s. I was using an older i5 laptop for image aquisition. This was taking approx 12s to download, save and start the next exposure (this was not a slow laptop by any means and had plenty of ram and an ssd). I made the following changes to try and improve my efficiency: I upgraded my acquisition laptop to a decent (and brand new) i7 - This dramatically cut interframe delay from 12s to 3s (without image history). SGPro changed the analysis; it is now an async process. Nina was always async and considerably faster. I switched to using 60s gain 0 L subs. I still use 60s RGB subs @ gain 76. I measured image download as 2s through my cem60 usb2 hub, 1s without. This gets me to approx 48-50mins of acquisition per hour in broadband) but there are still some things I am looking at: I normally interleave my frames (LLRGB-dither) to minimise dithers and balance any sky changes. However, this costs time (approx 2-3s per filter change). I may stop doing this to save the additional 2-3s. Dithers are pretty fast especially if they are only performed every few frames (approx 5m worth of frames), but the filter changes are costly. I use autofocus typically set hourly or every 2C. Looking at my FWHM measurements I think 2C is correct, but the time interval can probably be stretched to 2 hours (maybe more). An autofocus run typically takes a few mins. Has anybody else looked into this, if so what kind of things have you changed to make improvements? N.B. For narrowband I use 5m subs so typically get 50-55mins worth of acquisition per hour.

I have never used a polarscope with the polemaster. The pm has a wide field of view so you only need to be pointing vaguely north for it to work. In practice I try to get polaris somewhere near the middle of the screen before starting otherwise you can easily run out of az adjustment.

Have you run the PhD guiding assistant for a few minutes to actually measure your pa error after aligning with the polemaster? You might be trying to fix something which doesn't need fixing...

I get similarly good results with the 200PDS and Skywatcher CC: I am never sure whether to measure the curvature from a single frame or a stack of a few to minimise temporary affects such as seeing?

So: 1. This happened every/most nights you attempted to image? 2. It happens in all parts of the sky? 3. You are confident you are accurately focussed? If so, how are you judging this? 4. Presumably you are guiding? If it was high clouds the guide star mass would vary like this:

I used Pixinsight for that, but looking in DSS it does have a FWHM column so I assume it is measured as part of the analysis (albeit in pixels rather than arcsec).

"Occasionally I can swing to another area of the sky and that might be be sharp (or not)." Could you have tilt in the imaging train? Which lens are you using? Some of them can be very difficult to focus accurately, although it is strange you get this pattern every night?

I think DSS gives the FWHM after it has measured the frames (most likely in pixels)? I had a look at some of my recent frames and FWHM fell during the night which is what I normally see. This is data from a couple of nights, one with better seeing than the other and towards the end of that set (approx 3am) FWHM were approaching 2"

Have you looked at some good and bad frames to visually compare? Is the only difference focus?

Have you tried using the weighted batch preprocessing script? You dump your files into the appropriate windows, tell it you are working with cfa images, disable dark optimisation and it should do everything for you. Edit: The file you posted is pretty good: It had a strong colour cast probably as a result of the filter but this can be reduced with ABE, Photometric Colour Cal and SCNR. The workflow I followed is based on the Warren Keller Pixinsight book.

Bike shops????? At a time of global crisis what I really must do is go bike shopping...

Best bet is to test it and see, the bayer matrix on your dslr will effectively halve your resolution to 1.8"/px so you might get away with it sometimes. Having said that I wouldn't dream of putting my 200pds on a heq 5. My heq5 averages 1.2" rms and any hint of wind makes it worse.

Completely agree. I originally had an avx which I could lift intact from house to garden. I sold this after getting my cem60 but really regretted it because the cem60 cannot be lifted intact. The cem60 is a dream to use and guides <0.5" rms if the sky allows but it isnt worth the effort unless I know I am going to get >4 hours of clear sky. I have therefore bought a heq5 which I can lift intact with a widefield setup and doesn't require anything more than a power tank. I can easily use this when the weather doesn't allow for a full night imaging. In practice I have also found this faster to setup and way more usable than the star adventurer. Buy something you can use opportunistically and keep setup.

The cn thread is a superb resource for the asi1600. I use same length subs but vary the gain between l and rgb. I normally use gain 0 for l and gain 76 for rgb. @ f4.5 that leads me to 60s exposures. @ f5.9 I use 120s. @ f9 I use 300s. Something else to consider is your efficiency; lots of short subs with a long interframe delay can massively cut into your acquisition efficiency. If you use a slow computer with usb2 it could easily be >10s per frame which is a huge percentage loss. Try to get this delay <2s per frame.

I do something similar. I tell SGP my telescope is the ascom telescope simulator and connect. I then tell sgp to slew to my target followed by a solve and sync. This then syncs the ascom simulated telescope with your actual location. If you want visualisation beyond the coords you can hook cartes de ciel up to the same simulator and they work together...

Another alternative for longer focal length such as 200mm is plate solving. Using something like sgp for capture and astap for plate solving you can get precise, extremely fast pointing.

I follow the david ault workflow for PI and it works but panel matching can be torture: http://trappedphotons.com/blog/?p=994

The lum data is so detailed and clean compared to a dslr, when combined with rgb which appears to have some lp suppresion built in I just havent felt it necessary. The lp where i live is modern led streetlights so essentially impossible to filter. I also hate the way lp filters mess with the colour balance.

Thanks, that makes much more sense now...

The larger scope data could then be binned/resampled which would further increase snr? Having said that my experience with mosaicing is that matching broadband panels can be very difficult when light pollution and/or the moon is in play. Narrowband mosaics seem relatively easy because background levels are more easily matched. SGP has a feature requested to allow interlacing of mosaic tiles in an attempt to improve tile matching.

Also tried this and they work well but the proper lens heater is now a lot less hassle (and prob cheaper). I used this approach until the coowoo band included a controller, I have never needed anything other than the lowest setting and my 21ah phone charger seems to run for many hours without issue