A NIGHT TO REMEMBER

By Federico Arribas

“...Just then, the evil Guayota kidnapped the sun`s god Magec, and took him with him to the interior of the volcano Teide, plunging everybody into a total darkness. It is when the guanches asked for clemency to Achamán, - their supreme god - where, after a fierce fight, Achamán managed to defeat Guayota, took Magec out of Echeyde's entrails, and plug the crater with Guayota inside…”

From Guanche mythological culture.

Last September I went to visit my good friend Rómulo Márquez to Tenerife answering to a very kind invitation on his part. Among the many things we planned to do in the excitement of the occasion, we included more than one observational night to take pictures, as Tenerife’s El Teide volcano location is regarded as having one of the darkest and clearest skies in the world. He also planned for a visit to La Palma, also known as Isla Bonita by the locals, one of the 3 out of eight islands he hadn’t already visited. Both places are home of several local and international observatories we wanted to visit. Of our big observational plans, which included a Messier Marathon promoted by IAC for Saturday 19 on La Palma, we were able to complete only that Saturday night of astrophotography and observation in La Palma, ending up being one big success and producing our very first more-than-decent set of deep sky images ever, against all odds. This is the story of that night and its outcome.

 

MURPHY’S LAW AT ITS FINEST

I arrived in Tenerife on September 14th, and there had been building up severe weather all over the Atlantic from a few days before, so we feared the worst. By the time we were ready, 5 storm systems had broken in the Atlantic, two of which were hurricanes. One had gone due north between the Azores and Portugal, and was so large that one of its arms reached the Canary Islands strong enough to make their sky so overcast that it was useless for astronomical observation. Also, calima (Saharan air layer) from northern Africa had risen up and was stationed all over Tenerife and other islands providing a hazy layer of dust in the lower atmosphere up to a few hundred feet. It was the perfect storm. It seemed almost on purpose.

Rómulo was apologizing for the weather as if it was his fault, saying that never before anything like it had happened on the island since he lived there. By Thursday 17th the Messier Marathon was canceled, but it was too late to cancel our ferry and accommodation bookings, so after 4 days of forced tourism on Tenerife, we headed to La Palma, with no hope for better climate conditions.

BOYS WITH TOYS

A few days before my arrival Rómulo received his star tracker, the Sky Watcher Star Adventurer, which we found in AstroIlusión in Seville after getting many “sold out” responses in different physical and online stores. It turned out it was selling like crazy, maybe because of its many good reviews from trendsetters. He waited to unbox it until I arrived. 

As for the camera, we got a borrowed Canon EOS 80D. It came with two lenses, a 100 mm macro and a 18-135 mm f/4.5, which was our obvious choice. We also had a wireless intervalometer (another extremely useful tool) and a power pack specially for EOS cameras (8.4V 2A). Rómulo focused himself on learning to use both the intervalometer and the camera, which he did pretty fast. 

Testing the rig indoors

We read the Star Adventurer’s manual and tested battery life and other things before taking it to the field. On the tests we discovered that the mount consumes so little power that the power pack switches off automatically because it thinks there’s nothing connected to it. We solved the problem taking a small wireless modem-router to connect to it (we needed our telephones with us), so the power pack wouldn’t turn off. 

We also downloaded the Polar Finder app following the advice of a reviewer, because one of its reticles matched exactly the one in the Star Adventurer’s finder. It proved to be a blessing later on the field.

We had been preparing for the occasion by watching tutorials and reading manuals, reviews, and all information about capturing, stacking and processing, so we planned beforehand for possible targets, exposure times and approximate frame count for lights, darks, flats and biases.

We had done deep sky objects photography before, but with little to no success, despite the Meade 10” Schmidt-Newtonian f/5 we had at our disposal in Maracaibo, Venezuela, because of poor observational conditions and lack of hardware and accessories at the time, but we were already very good at setting up an equatorial mount and aligning a telescope..

 

WALKING AMONG TELESCOPES

A telescope collection

Saturday 9/19 came with good omens. Despite the nefarious weather forecast of the previous days, calima was receding, and so was the cloud cover. We decided to venture into a night of observation at La Caldera de Taburiente National Park, La Palma’s huge volcano. On its northern ridge, whose highest point is known as Roque de los Muchachos, are settled some big telescopes from Sweden, Finland, Denmark, UK, Netherlands, Italy and Spain, and the headquarters of IAC (Instituto Astrofísico de Canarias).

We arrived early to visit the compound and contemplate in awe the view from 2400 m above sea level of the 360° uninterrupted horizon. We then walked to the lookout, a privileged point of view from which you can see the volcano, other Canary Islands afar and some of the telescope domes.

From the lookout

On the way up, we meandered through the telescopes, stopping every few meters, because “this time we found for sure the perfect angle for a photograph” a few dozen times. We felt so privileged, so blessed we couldn’t believe anybody could take that view for granted. It was the consummation of a long overdue dream of ours (specially mine), we simple mortal beings.

We stopped at MAGIC’s helipad looking for a good angle, and there we found a guy who was also staying overnight for an astrophotography session, only he had a permit to stay within the IAC Complex that night. We couldn’t find out where to get one of those permits for a future visit, but we did find out that everybody else would be removed from its premises at 8:00 pm, including us, so as we returned from the lookout we started looking for a suitable place to stay. 

 

CAMP SIDEWALK

A parking lot box office clerk told us to try staying at the Roque de Los Muchachos Visitor’s Center. It wasn’t finished nor operational yet, but he thought we could probably stay at the parking lot, which was guarded by a security guard all night long. Once on location, the guard told us we couldn’t stay within the facility of the Visitor’s Center, not even in the parking lot, so after careful consideration we decided to stay at the sidewalk, which had a cemented widening protected by railing. It was right by the road and passing cars could be a problem, however the use of car lights was prohibited throughout the whole area, so we figured we were covered. The Visitor’s Center is located slightly lower than the telescopes, so the volcano ridge served as a natural cover for the few city lights that polluted the sky from the south. 

Camp sidewalk

Our spot was not bad, but the floor had a slight slope, so as we started setting up the mount we figured we had to pay special attention to the tripod leveling. First we aligned it facing north. It was a strange feeling for me to locate Polaris so far above the horizon. I was used to find it just a fist above it, so when Rómulo told me “it’s that one” pointing so high I thought he was crazy, only to realize the joke was on me. We leveled the tripod between the two of us, one dealing with the leg’s length and the other keeping an eye on the bubble level embedded in it. We spent some time leveling it up until we were comfortable with the results, then we used our phones’ levels to check it and it was perfect! (you know, the two circles lined up at the center and turned green). From then on we had to be extra careful not to hit any of the tripod’s legs. 

We then proceeded with the mount, which included the equatorial wedge, the dovetail and the counterweight. The wedge includes another bubble level, just in case you use a tripod without one, I suppose. As a slight breeze blew from time to time, we decided not to extend the tripod legs all the way out for extra stability so the mount was lower than it was supposed to be. Locating Polaris through the polar finder while adjusting its location in the reticle using the latitude and azimuth screws with the mount that low proved to be not an easy task, kneeling down and adopting uncomfortable positions. We used the Polar Finder app to know the exact position in the setting circle, and once we got it we had to lock the latitude using the lever in the mount, only to find that by doing so, the tightening moves away the position of Polaris. It is a design flaw. We solved it by estimating how much it would move (by then we had done it several times and had a pretty good idea) and compensating it by locating Polaris that much off, so when you tightened the lever it would fall right into place. We tried it several times until we got it right, and it took us some 45 minutes in total to align the mount to our satisfaction.

These two steps, leveling and aligning, were crucial to successful tracking when taking photographs. That perfect tracking lasted all night.

Then we finished setting up the rig by adding the camera, the camera power pack, the mount power pack and the intervalometer wireless dongle (on the flash hotshoe), after which we proceeded to balance the weight of the whole rig. We previously had used Velcro on the tripod legs and the battery packs to remove unnecessary weight from the mount. The tripod tray proved to be useful too, holding the router I mentioned earlier, lens caps and other stuff.

SHOOTING STARS

The rig in operation

Finally, it was time to start shooting. We had a Bortle 3 sky. We picked the Milky Way as first target because the Sagittarius area was already low in the western horizon. At 18 mm focal length (that is roughly 28 mm for a 35mm frame) most of the interesting area fitted within frame in vertical position. For framing, we took a few test shots with ISO 12800 until we got everything we wanted on display.  For the shots, we chose to go with one f/ stop lower than maximum aperture. Most lenses perform better using medium apertures in terms of chromatic aberration, blur, vignetting (light falloff) and geometric distortion, so we knew we should avoid maximum aperture. 

The focusing ring in DSLR lenses is not the best tool for achieving a perfect focus in astrophotography, and we didn’t have a Bahtinov mask. We used the 10x enlargement in the live view to better notice slight changes in star size while focusing. We took our time focusing, using a different nearby bright star for each target. For the Milky Way it was λ Sagittarii Kaus Borealis. For exposure time we wanted to be not too daring, so we set it for 1 minute. We also wanted to avoid too much ground and light pollution showing in the horizon in the last frames of the set. Then we programmed the intervalometer and started shooting lights, followed by the darks and the flats. 

We knew how long it would take each set, so we sat and enjoyed the view while we solved the problems of the world and gave form to new hypotheses on astronomical and philosophical issues. Basically, we indulged ourselves on the most rewarding activities associated with observing the stars. That’s why I loved the intervalometer so much, it gave us the time and freedom to do it. We even bonded with visitors Oliver (local) and Jeremy (french), both new to sky watching, showing them some constellations and stars, so they could find their way in the night sky, while sharing hot chocolate and biscuits.

Enjoying the view and the chat

Then it was time for M31, which took a lot of time framing. Then M33, which was difficult to focus because there were no bright stars nearby. And then we had time for one more object, and it was planned to be The Pleiades, but when we saw Orion’s belt already high above the horizon, we decided to switch. And that was it. We lifted camp and proceeded to go home.

 

COULD IT BE MAGIC

A few hours later, back on Tenerife, after we rested and were back on our feet, it was almost night again when we decided to download the images to the computer. I was leaving Tenerife the next morning, so there was no time to process an image as it should. But we couldn’t help ourselves and prepared to do a test. Our expectations were low, because so many loose ends and question marks were involved. All new equipment, site, procedures and techniques left a lot of room for error. We tried M31. Stacked the images in DSS and took our Autosave.tif to Photoshop. After we stretched the histogram a few times, we couldn’t believe our eyes. It popped up right in front of us in all its splendor. Dark areas figurines on the surface of the galaxy were clearly distinguishable. Stars were a little too big, as expected, but it was a very good base image to start with. Even noise was low and manageable..

Once at home in Oviedo, I processed the 4 images the best that I could, and the results are there for your enjoyment. For the first time in our lives, someone from GAZ or AZAFA was able to produce images of the horsehead nebula. We were left with an expanded sense of the possible, and with a thirst for more knowledge, better performance and more challenging objects to register. We wanted more!

Maybe that night was magical, or even arcane, or perhaps the providence conjured so that it came to be what it was… a night to remember.