Auto-guider Night Two

It's been mostly cloudy since the beginning of October limiting my skygazing and auto-guider familiarization. Last night I finally was able to put it all together.

The test was as tough as it gets. My second floor patio is pretty useless for skygazing with all the trees blocking my view except for a narrow ~ 15 degree opening to the south. The patio overhang blocks the sky above. Despite, my lack of access to Polaris, my rough alignment with north,  I managed a single star alignment on Nunki with the Celestron AVX using the AVX Quick alignment.

The forecast was for mostly cloudy so it was imperative I use whatever clear sky quickly. I slewed over to and centered M22 on the ASI294MC Pro sensor. A bright star was selected, the PhD2 button was clicked and calibration begun. With the F/6.3 focal reducer and diagonal EFL was calculated to be 880 mm. For this first try it became evident the guider was not tracking with considerable drifting by M22.

After a few stumbles with advanced settings I started getting a 'star moved too little' error. I reviewed the advanced settings in the help files which are pretty good. I had inadvertently unchecked the Enable Guide Output ... oops. Enable Guide Output box checked calibration went smoothly.

M22 had moved behind the trees by the time I corrected my errors. I slewed to and centered M75. Auto-guider calibration went quickly on the selected star and auto-guiding started. Focusing was not the best on either the imager screen or the auto-guider screen. Nonetheless tracking was spot on for a series of 8, 15 and 30 sec sets of 25 subframes. Great performance considering the mediocre conditions.

Fingers crossed, the forecast for Saturday is for mostly clear night skies. My hope is a good workout for this great little device at one of my darkish sites.

Orion Autoguider first night out.

In my last post I mentioned I had ordered an Orion Magnificent Mini Autoguider Package. It arrived early Friday afternoon giving me time to quickly unbox it, scan the instructions and familiarize myself with the device. The package consists of the auto guiding camera, a 50mm guide scope, mounting hardware and cables. 

I decided to head to Harvard, MA gambling on a better sky than my local park. I should have stayed local, saving the gas, because the sky was pretty clear when I return around 1AM. My goal for the night was to align the guide scope, do a calibration and image a couple of DSOs with guiding. Things did not go as planned.

Because the guide scope and the main scope were so far out of alignment it took me more than an hour setting up the scope hooking up the cables and using Polaris as a target aligning the guide scope with the finder. Complicating matters is sometimes the guide camera acts a bit flaky in how it normalizes the view. If  a star is present the background becomes dark. However, sometimes when the cap is on the screen would go completely white. In any case I did manage to get the guide and main scope aligned. 

I had considered using the guide scope as the finder on imaging nights. Unfortunately the flashing red LED on the back of the guiding camera makes it difficult to sight along the guide scope to aim at a bright alignment star. Thus it took my almost 3x longer than normal to do my usual 2 alignment star, 4 calibration star and all star polar alignment Thus the reason for re-installing the 6x30 finder scope. 

Once aligned I decided to test the scope on a globular cluster; as usual M13.  I goto pointed the scope to M13 and centered it. Here's where the night fell apart. The quick start instruction is to select a star near the middle of the auto-guider screen. If the box around the star is green your ready to go. Then you press the PhD2 button to start the process. Unfortunately, in my case the the PhD2 button was grayed; i.e. disabled. An indicator at the bottom of the view showed no scope selected. 

Hmm. I searched around the menus for whether there was some setting I missed but did not find it. I began to wonder if there was a problem with the clock drive. With clouds starting to move in a the Schmidt cassegrain corrector plate starting to fog from dew I packed up for the night and for the hour drive home. 

In the morning thanks to a 2015 thread by PHD2 enthusiasts I figured out the problem. You connect the camera via a dialog  where you also connect the mount. However the 'mount' is actually on the camera. But the mount selection was grayed out. It turns out I needed to connect all. Doh! PHD2 actually stands for 'Push Here Dummy.' I really did feel a bit dumb after last night.

Light Pollution Filter

It's embarrassing but I have had this Orion Light Pollution filter for a number of years for use in visual DSO viewing. Never, thought to use it with my previous or current deep sky imagers until last night (9/30/2018). My doh! moment came while watching an AstroBackYard Youtube video review of the ASI294MC Pro where the narrator admires the sensitivity of the camera even with filters. 

The images below were acquired using with the Orion LPF in heavily and increasingly light polluted Frederick Maryland. M27 was acquired using 15 sec exposures at using a Celestron 8 at F/4.6 on an AVX mount with tracking but no autoguider. The two nebulae were the same configuration but 30 sec exposures.  My near term goal is to acquire an autoguider and increase exposure times.

Messier 27

NGC6888 Crescent Nebula

NGC6992 

Update: I just ordered an Orion Magnificent Mini Autoguider. To date I have never imaged with guiding and it pretty much shows when images are enlarged. The stars are almost always a little misshaped or elongated for exposures longer than 15 sec. I've been content to tolerate these flaws.  The Celestron AVX tracks beautifully for it's size and weight but no mount is perfect. With the ASI294MC-Pro its time to go deeper with longer exposures with the additional benefit of guiding.

A few ASI 294 MC Pro Images

Before getting into the imaging it's valuable to note that ASI294MC-Pro was not recognized by SharpCap 2.9 forcing me to upgrade to  v3.1. To benefit from live dark frame subtraction I had to pay for the pro version only to find the dark frame subtraction did not work properly. I noted this to the developer who has worked with me to fix the issue which I'm currently testing. Recently, clear skies have been the exception. The following images were acquired without the live frame subtraction with dark frames applied during  Autostakkert processing.

Messier 17

Messier 16

Messier 22

Messier 27

Except for the exposure times all of the above images were averaged from 25 subframes using the following settings.  Messier 22 was acquired using 8s images. The other three images were acquired using 15s images.

Well...the ASI174MC-COOL did not work out

Ignore the publication date. This post was written around July 20th, 2018 but only published 8/8/18. I'll try for brevity.

The ASI174MC-COOL camera that replaced my mothballed but still working Meade DSI Color died TWICE under warranty. I suspect this was due to the camera drawing too much current and overheating while acquiring dark images for later use. When it worked the camera was productive and enjoyable to use despite its high amplifier glow. High Point Scientific was classy enough to  issue me a credit for the full camera price after the second failure. Thank you HPS.

I used the credit, plus an additional $311 to procure the popular ASI294MC-Pro. I've only had it a couple days but so far am impressed. I was inspired to get the 294 by the awesome Astrobin images taken by Robin Clark with her 14" Celestron Edge SCT with a 0.67x focal reducer. Although her imager is an ASI1600MC-Pro its pixels are a bit smaller suggesting the ASI294MC-Pro is a bit more sensitive.

I use an 8" Celestron SCT also with a 0.67x. Suggesting the 294MC Pro would be a good match. To my delight on my second night out with the new camera I was able to get this M-13 image, though sadly marred by a dust speck ring.

Update: I was not using flat frames at the time of this writing.

The image is also noisy as I was running at high gain and with short (8s) exposures and dark frames only averaged from five sub-frames. 

Early Messier 23

Stars in this early image are poorly focused. I never really got the knack of the graphical focusing aids eventually resorting to eyeball focusing on an enlarged realtime bright star dimmed by super short exposure times. This image was taken at ambient temperature with an ambient temperature dark frame because I lacked to cooling power cable at the time. 

DSI is mothballed in favor of ZWO ASI174MC COOL

The Meade DSI-C has been mothballed. In July after much research I procured a ZWO ASI174MC-COOL which was on summer sale at Moving High Point Scientific  Moving from the DSI has significant learning curve with a big payoff.

I use SharpCap 2.9 for camera control and acquition. The learning curve can be steep with its many controls and parameters. Fortunately it's well documented. I typically acquire SER video files in 1936x1216 or 968x608 pixel formats. Temperature controlled cooling boosts productivity as one can acquire essential dark frames before a night imaging session. . The Meade DSI-C with no temp control and  plagued by hot pixels required frequent acquistion of dark frames as the ambient overnight temperature changed. Hot pixels have not been a problem with the new camera that I have typically run at 10C and 15s exposure.

ASI174MC is not perfect. Its large pixels 5.86 microns make it a less than ideal solar system camera compared to its smaller pixel cousins or my slower acquiring Celestron NexImager5. Also, there is significant amp glow in the lower right corner, thus dark frames are essential for long exposures.

Over the next few days I will be posting images acquired with the new camera since its June procurement.