My journey in imaging M31

[Grant Fribbens]

I started back in mid 2019 the same as many others by first taking pictures with a Star Adventurer Pro of the Milky Way but really wanted to get images of other nebula and galaxies that are out there. I was frustrated with getting the star tracker aligned to my target and ended up in damaging my usb socket of my Sony A6300 when I added a guide scope which crushed the right angled USB cable and now I can no longer remote control the camera, which compared to the control of a Canon or Nikon was severely lacking anyway!

So I purchased a secondhand EQ-5 goto mount in December 2019 along with a Skywatcher 150PDS (which I have not used as it is quite often windy where I am and I did not take this into account) and also went for a William Optics Zenithstar 61 and FLat61A as I wanted the wide field and this could be used on my Star Adventurer Pro as well as doing bird photography, but due to my Sony camera issue and what I had seen about CMOS cooled cameras I went for a ASI183MC Pro which was appropriate for the focal length of the Zenithstar 61.  The ASI183MC Pro is great in that I can take darks and flats when I wanted as I have full control over the temperature of the sensor.

I have had many frustrated nights where I really could not get the focus right or polar alignment was just not right but I did get some decent images of M31, Soul Nebula and Eastern Veil with the EQ-5 but felt I needed something even better so was looking at an HEQ5 but due to the pandemic it was not available and would not be for quite a while so I sold the EQ-5 and decided to go for the EQ6-R Pro which is much heavier and can take heavier equipment later on. My first image with the EQ6-R Pro was of the Wizard Nebula and it was a delight to see.

When I started imaging I was stacking in DeepSkyStacker (DSS) and then attempted stretching in Photoshop which I just did not seem to be getting right. Then I decided to try the trial of AstroPixelProcessor (APP) and have to say found the UI a bit of a shock at first but once I added my images and saw the whole process from start to end I was really impressed with the final images that I got which were much better than what I had from DSS. Now I am able to have a library of darks and flats that I can just pull in to run a stacking session.

I really like automation and Raspberry PI integrations but have had to give up on my PI 4 Astroberry only because there are some great Windows apps that I want to run as well alongside indi/indigo and they just did not like working that well over networking (wireless or ethernet) so I have gone for a Mini PC XC30Y which runs Windows 10 but I have installed virtualbox which runs RaspiOS for running indigo and sticks onto the EQ6-R nicely with velcro.

So last week clearoutside.com was showing that there were going to be clear skies Friday and or Saturday so I made sure that I was prepared for my first fully automated session. I setup and did polar alignment using SharpCap and then did my focusing using the latest release candidate version of Astrophotography Tool (APT) 3.86.8, I had setup dithering for the first time as I had heard great things about doing this. I setup PHD2 and started guiding and everything looked very good. I did a slew to Vega, too a 15s shot gain 110 and plate solved to get my actual position and then synced that back to the scope and then did another goto and then saw Vega in the centre of the screen after another shot. Then I focused the Zenithstar 61 with the built in bahtinov mask and got it to 0.03 which I was pleased with but hoped that would be good enough for my session as I do not have an auto focuser (yet).  I then did a goto to M31, another plate solve to make sure that I was in the correct area, sync to the mount and goto again and a 30s shot to see that I was now in the correct area. Did a PointCraft show to Stellarium to check the rotation which I needed to make sure that M31 was diagonally across the ASI183MC Pro so as to get as much in as possible, but I have already found that I needed the Flat61R 0.8x reducer flattener which is on its way! Once happy I could finally leave the setup and let the plan run taking 120 x 120s exposures which was estimated to complete around 5am. So it was 1am so decided to go to sleep. Woke up the next morning to see the scope was in a very awkward position still tracking so really need to set limits in indigo as when I asked the scope to park the camera just touched one of the legs and now has a small scar! So now I have learnt how to add commands in an APT plan to make sure that the camera warms up slowly and the mount parks itself at the end.

This week I have been trying to stack the images but found that the result in APP was really bad and I kept on getting a blue spike on the left of the colour chart and the image had blue crosses around most of the stars and I thought that the dithering has meant that the images were now not stacking properly. I tried DSS again and it also complained about the images so knew something was wrong. So I when through everything to see what was wrong and I found a couple of things. First I had installed all the software onto the mini PC but had not told APT that I was using a one shot colour camera. So APP was getting the light images wrong so I did try overriding the RAW/FITS settings but the image was still bad. I almost though that my images were not good enough and that the session was a waste of time until I noticed that I had used a different gain for the lights that I had taken. Luckily I could just create a new set during the day with the cooled CMOS camera. I managed to find some software that could edit the FITS headers and batch fix the light images to make sure they show as 16bit RGGB bayer pattern instead of 16bit grey and then ran APP again and am now very pleased that I stuck at it as the image that I got is, and I hope you will agree reading this, my personal best so far.

I have felt that I have come on a long way since I started and have learnt many things along the way but getting this image has just encouraged me to keep going no matter what and when I see what other people have done or can do this also encourages me and this post is also to help encourage others that may be having issues to keep going and not to give up!

Clear Skies!

Edited October 13, 2020 by Grant Fribbens

[bottletopburly]

You can set a park command in apt , set a second line  of exposures with 0 sec exposure use the park command in script editor , so end of  imaging plan scope will park 👍 you can tell if it’s correct as second line will have an apostrophe next to line 2, nice write up of your journey btw .

[tomato]

That’s a great informative post and an excellent M31.

APP is excellent for calibration and stacking, and the processing tools  are pretty handy also.

Just looking at your set up photo, I’m not sure if that is your actual imaging location, but if it is you may need some pads under the tripod legs if your rig increases in weight. I set up on grass a couple of times and got that sinking feeling as the session progressed...