About the Object
NGC 474 is an unusual elliptical galaxy in the Arp 227 group at a distance of about 100 Mly.  It contains type II classification shells along with extensive faint tidal tails.  It has a morphological Type (E/S0 D), which is a lenticular-elliptical galaxy.  The nearby spiral galaxy NGC 470 lies at a distance of 110 Mly and is separated by only 5.4 arcminutes from the core of NGC 474.  NGC 470 has a morphological classification of SA(rs)b, an apparent magnitude of about 12, and an apparent size of 2.8′ × 1.7′.  NGC 470 is known to be undergoing intense nuclear star-burst activity.  The shells of NGC 474 have been studied extensively but they are difficult to explain.  The authors of one study argued that the tidal tails were formed because of a collision with a galaxy 2 billion years ago. 

When I first saw an image of this region, I was fascinated by this unusual galaxy and I wanted to give it a try with my equipment.  I gathered my first set of images early in 2022.  I started to process the data sometime last fall but I quickly realized that I didn’t have nearly enough passable data so I restarted the project—taking mostly lum-data. I finally finished up on Christmas Day and wound up gathering a total of nearly 600 subs of this object.   

Guiding Problems
So why did I take so much data?  The answer to that question leads into the problems that I’ve had with the scope.  It was working reasonably well early in 2022 but its performance has slowly deteriorated since then.  Sometime in the fall I realized that I NEVER saw acceptable guiding performance.  RA rms errors were ALWAYS significantly worse than the DEC errors and I NEVER saw rms errors less than about 0.3” rms.  Most of the time, the rms errors were 0.5”-0.6” in RA and 0.3” in DEC.   I started by recalibrating SkyGuard using a bright star and that made an immediate improvement but the guiding numbers still weren’t very good.  For this data set, I had to set my threshold tolerance for FWHM at 2.4” to pass even 10 percent of the data, which is HORRIBLE!  That’s as bad as I ever saw at DSW with my 14” scope.  I started closely examining my guide signal and I began to suspect that my L500 mount was out of tune.  The first thing that I tried was to do some unguided exposures and I learned that my scope couldn’t go for more than about 2 (maybe 2.5) minutes unguided without seriously trailed stars.  Whoa…that’s not right!  This system could easily produce perfectly round stars with 5-minute exposures before I sent it to Chile. 

So, I took a deep breath and tried retuning the mount—and it completely failed.  It wouldn’t tune!  It just gave me a bunch of “FAIL” error messages.  I contacted Planewave and at first, they were great.  They looked at my tuning data and told me that something “big” was loose.  I had the guys at the observatory inspect the mount for rubbing or over-tensioned cables and to look for anything loose.  They tightened everything in sight and sent me pictures of the guide camera, which had developed a “wiggle” (when moved by hand).   At that point, the guide camera is just barely working so I wrote up detailed instructions to replace it with a spare that I have down there and submitted a service ticket.  That was my only hope to get the camera tightened up on the ONAG unit.  I think that the techs turned white at my 5-pages of instructions and that conversation went silent.  In the meantime, the service guys at PW tweaked my tuning data and asked me to test it.  I agreed and told them that if it didn’t work, I was going to try to retune it again.  They didn’t disagree. 

After two months, nothing we did made any difference—the guiding was still horrible.  So, I tried a quick retune and it again failed.  I contacted the PW guys to ask how to reload the old tuning data and they hit the roof.  They sent me a moderately nasty email telling me that there was no way to reload the old data and that I had just squandered everything they had done to help me.  I referred back to our last action plan and pointed out that I had simply done what I thought we had agreed to.  That’s when they went totally radio silent on me—I’ve never heard another word from them.  I know how to escalate this but until I can get down there to work on the scope myself, these guys aren’t going to be able to do anything else at this point.  I did a single point retune and when the scope is pointed in that one spot in the sky, it works better than ever.  (Tonight, I was seeing 0.15” rms errors in both axis—just before my main camera failed and I had to shut it all down.)  Of course, the performance seriously falls off in other parts of the sky.  I’m pretty sure that the tuning problem is related to the loose camera AND the wiring umbilical that goes to the cameras.  When I get down there, I have a pretty good idea of how to get it going again but if it doesn’t work, I’ll be going back to Planewave.   

Of course, this all begs the question of why Planewave would supply such critical software that can’t save and retrieve different tuning models?  That’s not hard to do and it seems like it would save a lot of trouble when there’s a problem.  I’ve noticed similar oversights with the PW3 thermal control software as well.  Most of the basics are really well done and the code seems really stable, but features that are important in the real world are completely missing.  It’s as if they only set this stuff up in the shop and never use it in the real world where problems actually happen.  I don’t know.  I’ve observed that they don’t do a good job of listening to their customers.  I’ve pointed out a number of problems to them and they rarely fix things.  A couple of times they have completely ignored my offers to help them—totally free of charge.  In my view, the company is infected with a very serious case of NIH syndrome. 

Camera Troubles
At the same time, I’ve been having serious problems with both my QHY600M-Pro and the Horizon II guide camera.  Sometime in mid-August my QHY600M started to randomly have trouble transmitting correct data.  I haven’t gone in with a debugger to look at the data itself but it appears as if it is transmitting only the upper byte of the 16-bit data word from each pixel.  That means that the image shows stars, but that the overall image looks very dark with either no low-level data or data in the least significant byte that’s just low-level noise.  It’s basically an empty image that shows a very strange histogram distribution.  I tried reloading drivers, fiddling with ASCOM settings and rebooting everything in sight.  At first, I thought that the camera was dead, but along the way, I found that it would randomly connect to the PC in a way that it worked!  I couldn’t tell if rebooting the PC, just the camera, or both made any difference in whether it would connect properly.  Once it connects properly, it will keep working properly—as long as I don’t turn it off.  So, I’ve left the system running full-time for many months now.  It takes anywhere from 4 hours to 2 days to get the camera properly connected after a power glitch. 

It took about 6-weeks for QHY to respond to my request for service but when they did, it wasn’t very helpful.  They spend about 4 hours cleaning up everything with the latest drivers and everything else.  A couple of times they tried to convince me that the camera was working properly but I was able to shoot down that notion quite easily.  Finally, they simply declared that the camera was broken and that I’d need to return it for service.  Yep…I already knew that, but at least they agreed with my conclusion. 

I’m installing a second system at Obstech and that has delayed my ability to get this scope repaired.  I have another QHY600M-Pro ready to go down there and a Moravian camera on order but there is no telling when Moravian will deliver.  I’m going to go down there in about 3-weeks so if the Moravian shows up in time, I’ll install it and keep the QHY as an emergency backup for my other scope.  At this point, I’ve got expensive cameras coming out of my ears.  Remote imaging is not for anyone who is financially timid or faint of heart!  All of these equipment problems are also a big part of why I’ve been posting so few images for the last 6-months. 

Yeah, Even the Guide Camera Has Gone Flakey
As I mentioned, the Horizon II camera has developed its own problems.  It suddenly started displaying a huge amount of dark current—on the order of half of the signal!  I deal with it by subtracting a dark frame but that seriously impacts the SNR of the guide image.  This is the second ATIK camera that has failed, so when I head down there, I’m replacing it with a ZWO ASI1600 uncooled guide camera.  The ASI1600 is uncooled so it’s much smaller, much lighter, and it’s much cheaper so hopefully it will work better.  And if (when?) it breaks, it’s half the cost of the ATIK camera. 

New Camera Options from FLI
While I’m on the subject of cameras and reliability, I’ll quickly mention that I just returned from SPIE in San Francisco where I spoke with Gary McAnally from FLI (now a part of IDEX).  He gave me a list of new cameras based on the Sony IMX4NN sensors that they will introduce over the next 6-12 months.  I’ll post more about this on the forums.  In my experience, FLI cameras have been bulletproof in the field.  They just work—year after year.  I think that FLI is REALLY late to the game but at least they aren’t as dead as I thought they were with respect to astro-imaging. 

Processing this data
With only 15 hours of barely useable data, this turned out to be a very challenging data set to process.  The most immediate problem were gradients and stray light from a bright, out of field star.  I’m not sure why but all four of my channels were riddled with similar gradients.  Maybe it’s due to IFN but I doubt it.  I tried every trick I could come up with to deal with it but the results in every case were barely passible.  The challenge is that you have to really go deep to display this galaxy properly.  I struggled with this issue so much that I considered tossing this entire data set to try again in a year.  The point is that this image barely squeaked past the starting gate.

The second problem is getting the colors to calibrate properly.  I’m sure that you are thinking that SCC should take care of it…no problem.  Of course, that was my thinking too but after multiple tries, I ended up with a mess every time.  The colors were obviously wrong with a weird salmon colored bright star (HD7991) and bright green halos around the fainter stars.  I tried calibrating before applying BXT, after BXT, and by using NGC 470 for white balance.  Linearizing the filters against a master produced a mess as well.  I tried calibrating just the pure, raw data and nothing looked plausible.  Finally, PI crashed forcing me to start over from scratch.  At that point, simply combining the raw RGB channels magically showed believable colors.  Don’t ask why…I just went with it.  I processed the RGB data and the LUM data separately and then separated the RGB data into LAB components.  I then replaced the L component with my carefully processed LUM data and recombined the components.  That approach worked well to combine the processed linear lum-data with the RGB data.

I’m not very happy with how the glow around HD7991 processed out.  At the most fundamental level, there shouldn’t be all that glow.  I suspect that a lot of it is due to scatter from all the dirt on the optics, but some of it is almost certainly coming from scatter from the mid-spatial frequency surface roughness in the Planewave optical surfaces as well.  Either way, it’s undesirable and it leads to challenges in processing. 

I've include and extreme stretch to show the extended super faint tidal tails in Rev D.  Rev E shows a close up of a very distant galaxy cluster that shows up in this field as well.

I often encourage looking at a close-up view of my images; but, not this time!  In my opinion, this is among my most marginal images.  I post it more as a mile-marker than an example of my best work.  Of course, after all of my struggles it gets hard to tell if it’s any good so let me know if my judgment is skewed.  It is certainly an interesting object and for that I’m happy to add it to my gallery. 

John