Grab a cup of coffee:  This image has a story--and it's a long one.  It's about a beautiful object, the challenges of remote imaging, an amazing 3-week, six country trip by private jet, a night of observing with a 40" scope under the best sky in the world and fixing my scope along the way.  Who said that remote imaging is boring?

Target:  M83, The Southern Pinwheel
This image of M83 is the inaugural image for my repaired and re-commissioned 20" scope in Chile.  M83 is a large, detailed, and colorful grand design spiral galaxy that's an iconic object for anyone with access to the southern sky.  It has a morphological classification of SAB(s)c, which indicates that it is a weak barred spiral with loosely wound arms.  M83 lies at a distance of 14.7 Mly and subtends nearly 13' x 11.5' at an apparent magnitude of 7.5 making it among the brightest spiral galaxies in the sky.  New stars forming in clusters along the spiral arms produce intense ultraviolet radiation that is absorbed by diffuse gas clouds containing hydrogen.  The hydrogen re-emits the UV light in both deep red and fainter blue light creating glowing magenta-colored clouds of gas lining the spiral arms.

Camera Failure!
Back in late December after shooting the Sculpter galaxy, I started to have trouble connecting to my guide camera...and that's never a good sign.  For a few days, I could cycle the power and get it going but eventually, I couldn't get it going--no matter what.  The techs at the observatory swapped cables and we just couldn't get it going.  I wasted 2-3 weeks working with a well-meaning vendor who tried to get ATIK to drop ship a new camera from the factory in Portugal directly to Chile but that effort eventually fell through.  In frustration, I finally ordered a new camera from another distributor and FedX'ed it to Chile.  By the time the dust settled, I had been down for over a month and the cost of getting the new camera shipped was somewhere in the neighborhood of $350.  All in,  I probably have the most expensive guide camera in Chile!  (In hindsight, it would have cost the same to use a less expensive ZWO camera and sent two of them with the scope.)  The guys at the observatory mounted the new camera and we spent a few hours getting it focused.  And then...the new camera started to drop off line.  Oh, oh!!

Fixing a remote scope is a game of 20 questions.  Ask the right question and you can figure it out, but that often requires wading through a lot of dead ends.  At that point, I asked the tech to read the voltage on the power supply in my cabinet.  Instead, he sent me a photo of the supply display panel and I immediately spotted a problem.  The voltage read 11.5 VDC so I asked him to turn it back up to 12.5VDC.  When I got the message that 11.5V was as high as it would go, I looked at the photo again and did a double take.  The current draw showed 80 amps!  That's 80 amps from a supply that's only rated to 25 amps!  I quickly turned it off.  We disconnected everything and turned on the supply to see the indicated current draw go down to 66 amps.  Sheeze...now what?  Clearly that supply was dead, so I ordered a new one.  In the meantime, we pulled the anti-dew system wiring and reconnected the OTA power to use the anti-dew power supply and tried the camera again.

No joy...the camera would not connect.  Now I was worried that we might have blown the new camera with the faulty supply.  But first, we ran a new short USB3 cable to the camera and bingo, the camera connected.  Whew!  It took some searching but the techs eventually found a new, longer active USB3 cable to install and I ordered another couple of spare cables--just in case.  We got the scope running and the techs were super helpful, but I couldn't shake the feeling that the camera wasn't properly focused and I started to think seriously about how to get down to Chile to check everything myself.

Out of the Blue
By then, it was late-January.  Omicron was raging and the State Department had placed Chile on a level 3 Covid alert with a recommendation to avoid travel so I was scratching my head about what to do.  On February 4, I was in Tucson with a couple of house guests when I received a text message from my friend Don in St Croix.  He had signed up for a month long, 5-star flying tour of S. America in his airplane.  He had invited another couple to join him and his wife, everyone had prepaid for the trip, and shortly before departure he ran into a show stopper.  Don flies on a special issuance FAA medical certificate and due to a massive backlog, the FAA couldn't renew his medical before he was due to leave on the trip. That meant that he wasn't legal to fly without a backup pilot who could act as PIC.  I'm rated in Don's airplane so he was checking to see if I was interested in joining the trip--all expenses paid.  There was just one minor catch:  I had to be ready to leave in 2 days!

This was the trip of a lifetime and my wife and friends were supportive so I jumped at the chance.  I spent those two days filling out paperwork and packing.  There would be 5 people in a 6-seat airplane along with gobs of baggage so I looked at it like a backpacking trip.  Weight was going to be a huge limitation!  I took only essentials and weighed my toothpaste to make sure that I was as light as possible.  There were 4 airplanes (3 jets and a turboprop) on the journey so I jumped on an airliner to Costa Rica to meet the group for the leg to Peru.  Because our airplane was so heavy, we had to stop along the way in Panama City for fuel but we eventually caught up with the group in Guayaquil, Peru where we spent a couple of days.  From there, we entered Chile and went hiking in the northern Atacama desert.  The entrance requirements for Chile are the strictest in S. America.  We had to do Covid tests and quarantine until the results were in.  Masks are mandatory EVERYWHERE and you need a QR code to go into any restaurant or public building.  They are super serious about controlling COVID--and no one argues about it!

We traveled on to Argentina, Uruguay, back to Argentina, down to Patagonia, before heading north back to Santiago about 3-weeks into the trip.  Along the way, I learned that two of our passengers were leaving the trip in Santiago and that another rated pilot and his wife were joining at the same time.  Bingo!  Don would have a pilot to help him and that was the opening that I needed to jump off the tour to work on my scope.  My buddy Don used to be on the board for Steward Observatory at the University of Arizona and he wanted to join me for a tour of Obstech.  He said, "This sounds way more interesting that sitting on tour bus driving around Santiago!"  Back at headquarters, the tour managers weren't super keen about the whole idea but Don would only spend a day doing his thing and we convinced them that it would all work out.

Heading to the Observatory
We picked up Vincent Suc (one of the two owners of Obstech) in Santiago and flew north to La Serena where Vincent arranged for a ride out to the observatory.  The drive from La Serena takes roughly two hours and the last hour is on dirt roads.  To say that Obstech is in the middle of nowhere is an understatement.  Wow...it's on a mountain at 5,150' and the only folks living out there are around 15 widely spaced subsistence farmers making a living by producing goat cheese.  The last mile up the mountain is on a very winding, narrow, private dirt road owned by the observatory.  The last hairpin is so tight that it requires backing up and repositioning to negotiate the turn.

Obstech
Obstech is a private hosting facility with multiple roll-off roof buildings (7 - I believe), a domed observatory (containing a 0.5 m scope for the Atlas program run through the U. Hawaii by an astrophysicist who actually used to work for me in his previous life as a programmer), along with 4 domes for the Chile Scope complex run by the Russians.  The Chile Scope complex is fenced and operates independently on space leased from Obstech.   Power comes from a large solar installation, banks of Li-ion batteries, and a backup generator.  High bandwidth internet is provided through a radio link down a nearby valley.  The LSST site is visible to the north at a distance of maybe 10-15 miles or so.  There's a small dormitory with a kitchen, a single bathroom, and a shower.  Water is trucked to the mountain every 3-5 days so conservation is the rule. 

One note on the name.  Obstech is the company that owns the land and runs the hosting observatories.  Sometimes it's called "El Sauce Observatory", which also appears to be the name of the fenced observatory on the same mountain top that contains the Chile Scope and Telescope Live--both run by a Russian business.  El Sauce refers to the location of the observatories; whereas Obstech is the company name.  I find the use of multiple names for the same site to be confusing so going forward, I'll refer to the hosting facility as "Obstech."

The whole project started in 2013 with a dream, a donkey to haul a Celestron up to the mountain for site assessment and ultimately a government start-up grant.  It took nearly two years to secure the land (about 120 acres).  The facilities have evolved to include a standardized design for the roll-off roof buildings and the entire operation appears to be VERY professionally run.  There are always at least 3 techs on-site every night who can help with just about any problem.  My scope was a notable exception but the staff on the mountain normally set up and configure most of the telescopes when they first arrive.  My guess is that at least 80% of the scopes are on Planewave L-series mounts.  The median aperture might be over 0.5 m, with numerous 0.5, 0.6, 0.7 m scopes along with at least a couple of 1 m scopes.  One guy (I'll leave out names) must have 7-8 very large aperture scopes spread throughout the various buildings.  Interestingly, the newest 1 m scope is owned by a guy who bought it as his very FIRST telescope!  It is festooned with multiple cameras and a spectrograph.

As the sun fell on that first night, the temperatures fell just enough to be slightly chilly.  The sky is clear and the wind is calm virtually every night this time of year.  By midnight, it was darker than the inside of cow.  I thought that I knew what a dark sky looked like but this was a whole new level.  The Milkyway cast a shadow...seriously.  We could clearly see the Gegenschein and the seeing was sub-arcsecond so the stars looked steady and bright.  Don and I were slack jawed.  It is hard to convey how beautiful the sky is out there.  It was like standing at a porthole looking directly into space.

Don helped me and as we finished adjusting the new guide camera on my scope, Vincent came over and said, "Come with me.  We have a treat."  Matt Dietrich from Planewave was there and he was putting the finishing touches on a new 1-m scope that he had just installed.  They put an eyepiece on the scope and we spent nearly 2 hours observing various amazing objects.  The views through a nearly 40" scope on a night with sub-arcsecond seeing were beyond stunning.   The Ghost of Jupiter was bright blue and very detailed.  The Tarantula nebula looked 3D and the dust lanes of Centurus-A jumped right out.  Omega Centaurus sparkled like a jewel in 3D.  The dust lanes along the edges of M104 where easy to see.  Wow...what an experience!

The Russian Connection
The folks running the Chile Scope have a close working relationship with Obstech and the three Russians who happened to be there working on the mountain came over for dinner and some serious drinking on my second night out there.  Dennis is a stout, serious guy who worked each morning with his shirt off while listening to head banging heavy metal blasting from a boom box.  At dinner, he wore a yellow T-shirt with CCCP emblazoned across the front in big burgundy letters.  He demonstrated the proper Russian way to do whiskey shots by giving a long toast in Russian before up-ending his glass.  Another Russian guy, Igor, chided everyone at the table about needing Russian drinking lessons if they were going to keep up.  In contrast to Dennis's serious demeanor, Igor had a friendly face and he was laughing all the time.  We didn't talk politics but those guys were obviously not happy about the events in Ukraine.  Flights were cancelled so they couldn't get home and when I left, they were talking about the idea of buying a house in Chile to wait it out.  It was a sad situation that those guys were trapped and couldn't get home due to events beyond their control.

Finishing Up and Heading Home.
In the end, I was able to clean up the wiring mess that had accumulated as the techs had worked on my scope over the months.  We cleaned the mirrors with a nitrogen duster and Matt helped me to tune my mount for optimum operation.  After 3 nights of little sleep, I was trashed and joined Vincent and Matt for the 8 hour drive back to Santiago.  We stopped for a really excellent seafood lunch on the way and arrived about 9.5 hours after we left.  The next day, I caught a flight home and after about 19 hours arrived back in Tucson.  I'll post a few photos of the site so you can see what it looks like.

CMOS Imaging Considerations
I've been in some ongoing discussions about the best way to operate cameras with the IMX455 sensor and this is a good opportunity to pass along some thoughts.  In my previous posts about optimizing the match between my F/6.8 optical system and the QHY600M camera, I discussed the impact of using smaller pixels on this system under optimum seeing.  There is another perhaps more important point about how to manage the data to maximize dynamic range.  QHY (and other manufacturers) allow image data to be binned on the camera before downloading.  In order to maintain the full dynamic range of the camera when using 2x2 binning, the data requires an extra 2 bits (4x) of depth.  That means that the full 16 bit ADC well depth of each pixel requires 18 bits when binning 2x2) to avoid saturation.  QHY (and other manufacturers allow both 18 and 20 bit downloads but that requires modification to the driver and since every imaging program will require a 32 bit word, the data will have to be padded.  Alternatively, you can get around this limitation by simply downloading the full 16 bit, non-binned data and subsequently bin using floating point during processing.  The amount of data involved is the same in both cases and you'll gain a factor of 4 in dynamic range over binning on the camera and downloading using 16 bits.  

During my visit to the observatory, it turned out that Matt was using 2x2 binning to image the exact same field with a PW24 that I was imaging with the same camera and same exposure time on my PW20.  We compared results and I was able to show him how he was overexposing stars that were not saturating in my images.  I think that he was convinced.  This image here is shown at full 1x1 sampling so it's a pretty big image (at 6k x 6k px).  Be patient for it to load when you zoom.

The Image
It seems like when I lay off of processing for a while, it takes multiple tries to get back in the groove and this image was a prime example of that effect.  First, I had trouble getting the colors "right".  I screwed up masking and destroyed the stars in another version.  Then I screwed up the color processing and introduced a lot of color noise.  In this final version, I applied virtually no noise reduction.  I did apply masked deconvolution to the galaxy core and although I tied to be conservative, I might have pushed it slightly too far.  I crossed checked the fine features against the original data to insure that any worm-like features were "real."  Still, there might be some pixel peepers who might object but I gave in in an effort to finally wrap it up.  To mix in Ha, I used the method pioneered by Vincent Perez and Martin Pugh to derive the pure Ha signal which I then added back into the red channel before doing the LRGB combination.  This approach avoids screwing up the overall color balance in the image and accurately colors the Ha regions.  Finally, I reduced the saturation a bit in the final version to (hopefully) make it appear a little less color-amped and more natural.  Hopefully it works beyond my monitor.  

As alway, C&C are welcome so fire away.

- John