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Interview with the creators of the Clear Sky Clock

Introduction
Today we are talking to two very data-oriented gentlemen. The first is Allan Rahill, a most avid and accurate forecaster of clouds and clear skies, particularly for amateur astronomers. Allan collects the data for the second gentleman, Attilla Danko, and his greatest invention: the Clear Sky Clock (CSC) which puts Allan's data to good use in forecasting sky transparency for specific observing sites. This service for amateur astronomers in North America is provided gratis; Rahill and Danko work in their own spare time.

Attilla Danko, clear clock wizard, is originally from Hungary, transplanted to Ottawa, Canada. Allan Rahill, the data master, is a French Canadian living in Montreal, Canada. Danko states that he is a "software weenie by profession." Rahill has been an amateur astronomer for 33 years. He says he keeps a 22-inch Bartelised Dobsonian in the back of his car, and a C-14 in his backyard observatory. He has been working in meteorology for 22 years.

Lydia:
How did you become interested in astronomy?

Attilla Danko:
"In the first grade I borrowed a book from the library called "The Stars" to read at home. To use a phrase from the 60s: 'it blew my little mind.' It had left me with a permanent sense of wonder.

Lydia:
Interesting that you remember the names of the book. Attilla tells me he first started observing at age 12, "with a Tasco refractor, and again, in my early 20s with a Dynamax 8 SCT."

Attilla Danko:
"I had no idea why I couldn't see anything, so I stuck to reading about astronomy. It wasn't until later when I joined an astronomy club in Ottawa and started attending star parties that I figured out what observing really was and that it was so much fun."

Lydia:
Allan, tell me about where you work: the Canadian Meteorological Centre (CMC).

Allan Rahill:
"It is the weather centre where worldwide data is collected by our powerful computer facilities and where new weather models are developed and are run twice daily. I am lucky to have the best weather tools to work with each day which also help to plan astronomy trips. I share this information with local clubs advising when there are excellent seeing conditions."

Lydia:
So, how did you get into this hobby?

Allan Rahill:
"More and more amateur astronomers were calling me at the office and at home for the weather. About 2 years ago, Arny Alfeim, a CMC employee, created a high resolution cloud forecast map. They were infrared images forecast by the regional model for up to 48 hours. I realised they were quite accurate and I was amazed at the quality.

"Here's an example of such a forecast. That was one and a half years ago, and my site was only geared toward Canada and the Northern US. Then I emailed clubs across the US announcing this product. I gave lectures at several clubs and after finding some had difficulty in understanding the infrared pictures, I created the cloud forecast for astronomers. Like Attilla, and many other astronomers out there, I also had frequently driven for hours only to find poor sky conditions. So I developed the sky transparency forecast which is based on humidity. These images were tuned from amateur astronomers' observations."

Lydia:
So this is where Attilla stepped in?

Allan Rahill:
"Yes, Attilla got the idea to produce the CSC for exact localities and transformed UTC to local time."

Lydia:
Allan and Attilla both comment on the sharing attitude of the astronomy community and how "the spontaneous ideas of amateur astronomers have helped to improve observing nights for all."

Attilla Danko:
"Indeed. The short amount of time I have to spend observing has become increasingly precious to me. It's one of the reasons why I really appreciate Allan's astronomy forecasts, and why I created the Clear Sky Clocks."

Lydia:
These CSC's have been a great help to everyone I know who has used them in the amateur astronomy community.

Attilla Danko:
"Well, I want no one to miss a clear night. If it hadn't been for the Clear Sky Clock for my home town, I would have slept through the 2001 Leonid storm."

Lydia:
Ah, the Leonids. Maybe the best light show of the decade! So what do you guys enjoy observing up in Canada on a clear and cool mid-summer's eve?

Attilla Danko:
"Firstly, galaxies. Particulary big bright spirals. I bought a 25-inch Dobsonion telescope just so I could see the spiral structure in M51, which is my favorite galaxy. I also love to strain to see 15th and 16th magnitude galaxies. I use their visibility as a test of sky transparency. Secondly, supernovae. They scare the heck out of me. Every time I see them, I hope all the sentients from 50ly around caught the last Airbus out of the system. Thirdly, quasars, particularly the Lensed Quasar in Ursa Major near NGC3079. Then, planetary nebulae. They come in an endless variety. Finally, globulars. M15 is my favorite, particularly as one of its zillion stars has burst into tiny 15th mag. I've managed to glimpse it only once."

Allan Rahill:
"I also like challenging planetary objects such as Pease 1 in M15, which again, requires good seeing and high power for one to succeed in viewing it."

Attilla Danko:
"Big emission nebulae. Like M42, The Veil and the North American Nebula. These are just breathtaking in a short focus refractor with a wide field eyepiece and narrowband nebula filter."

Allan Rahill:
"I am a dedicated observer of planetary nebulae and edge-on galaxies. I always look forward to the best seeing so I can boost my 22-inch home-made Bartelised Dobsonian to 600-1200x. These objects have a lot to offer with a lot of easy-to-spot detail at high magnifications.

"The Cat's Eye Nebula gives me the impression it is looking at me, the Clown Nebula is weird as it looks like a clown at any angle we look at it, the Little Dumbbell resembles a Barred Spiral Galaxy. The Saturn Nebula at 1000x magnification is just incredible with two rings and fine details. I also enjoy NGC 246, NGC40, NGC3242 (Ghost Nebula) and lately IC418 which appears pink at 200x magnification. All among my preferred planetary nebulae."

Attilla Danko:
"And let's add to that - planetary detail. I like to watch swirling inside the Great Red Spot, seeing Io as a little lemon-yellow disk in front of Jupiter's beige bands, endless spots, ovals and swirls in Jupiter, fleeting detail on Ganymede, and the rings of Saturn. (Don't let anyone tell you big Dobsonians can't show planetary detail.)"

Attilla Danko:
"The Moon is so often overlooked but it is a source of incredible detail. I have seen detail in the Floor of Schroter's Valley with my 25". (25" to look at the moon, you gasp!)

"Well, with my little refractor, the blackness of the maria, the brilliant white of the mountains, and the peppering of tiny craters down to the limit of visibility make it a feast for the senses that is very satisfying! Solar prominences, faculae, and what looks to me like cat hair on the Sun.

"The Sun is fascinating to look at with the right filter. It's one of the few astronomical observations where you can see changes from minute to minute. It's much like watching clouds."

Allan Rahill:
"One of the most impressive objects to me is the Swan Nebula M17 as seen with the 'BinoViewer', sitting back on a lounge-chair and spending time enjoying all the swirls and deep contrast. I get the same 'warm and fuzzy feeling' as I do looking at the classic M42 at 400x (again with the BinoViewer) where a half dozen more stars are easily seen in the background of the Trapezium."

Lydia:
And your Clear Sky Clocks definitely let you know whether nocturnal viewing your favorite objects is possible in a specific location!

Allan Rahill:
"Yes, and when the seeing is great, I have difficulty leaving the giant planets. It is so impressive to look at detail at 800x magnification. It is a rare event at our latitude (about 11 nights a year), but during these clean and steady nights, I remember looking at specific detail on Ganymede. I always use my BinoViewer for planetary observing."

Lydia:
So, Attilla and Allan, you are definitely not armchair astronomers!

Allan Rahill:
"Not by any means!"

Attilla Danko:
"I consider myself an eclectic observer who observes for the pure pleasure of it, for 'the wondrous', not because I am trying to accomplish anything. I don't do CCD imaging or collect scientific data (like photometry or occultation timings), yet I have the highest respect for everyone I've met who images and collects scientific data. (I have been most lucky in having met people who have done world-class work in both fields)."

Lydia:
But you both seem to be so gratified by what you see! Why not do CCD imaging?

Attilla Danko:
"I don't do any imaging because I figure I can wait to do that when my eyesight begins to fail. Besides no image, no matter how wonderful, has caused me to spontaneously swear. But I carry on like that at the eyepiece all the time. For me, images simply do not carry the emotional response that using one's own retina does."

Lydia:
Okay, so what else catches your eye?

Attilla Danko:
"One other thing I'd like to do, which is more important than object lists, is public astronomy. I take my 25-inch scope to public star parties and show 200 people a bright globular like M13. If they don't cry out with an expletive, I know the scope has been nudged off target. I also do sidewalk astronomy to show passers-by the moon in my little refractor.

"It is incredibly gratifying to meet people who have never looked through a telescope before swoon with delight and confess an unrealized interest in astronomy since childhood."

Lydia:
How important is it for children to appreciate the skies?

Attilla Danko:
"It's especially cool to let kids look through a scope. I figure the first person who will land on Mars is a kid now. A look through a scope might make the difference between becoming an astronaut or a lawyer."

Allan Rahill:
"I have three young boys. Only the youngest one is interested in astronomy. He likes all the electronic gadgets around my homemade 22-inch telescope. I bought him a second hand C8 last year and he is quite happy showing celestial objects to his best friends and to the public when we go to star parties!"

Lydia:
And the accuracy of the clocks allows you to do all this?

Allan Rahill:
"There is evidence that they are accurate about 80 to 90 percent of the time. It could well be the best forecast for astronomers in the world right now."

Lydia:
Gentlemen, tell me more about the how and why of the clear sky clock.

Allan Rahill:
"As a meteorologist, I am amazed at the quality of this product. Last fall I added two windows for the southern US States. For the southwestern US these are good, but for the southeastern US, all weather numerical models have problems in forecasting deep convection from April to October. I am proud of the CMC products however most weather models, including high resolution ETA (US) models have the same problem in handling these conditions. We have a new regional model with 15km resolutions and a new physics package, to be released in June, that will perfect this resolution problem. The NE, NW and SW quads are still quite accurate for all seasons."

Lydia:
Attilla what was your motivation to invent the clock?

Attilla Danko:
"As many inventors will admit, I was inspired by laziness. I knew about Allan's very accurate astronomy forecast maps. Meteorologists draw maps because they want to understand complete weather systems. I just wanted to know when it would be clear in my back yard. So I designed the first clear sky clock to do just that: to extract data from Allan's many maps for just one location. Most do not respond to a minor irritation, like the one I have described, by writing thousands of lines of code. But it became real handy when my friends started asking me for CSCs of their own. I didn't expect to do hundreds of them. But now it's too much fun to stop. I really enjoy doing something that helps my fellow amateur astronomers."

Lydia:
So how do you convert Allan's maps into clear sky clocks?

Attilla Danko:
"I wrote a script to detect when Allan's maps get updated, which would also download them. Using my own optical-character-recognition routines, I decode the dates then figure out which of Allan's maps are the right ones to use (non trivial when his program has hiccuped). I reverse engineer the map transform, so I can translate latitudes and longitudes to precise pixel locations. I do a bit of pattern recognition on the map overlays and moving cloud fronts to pick the right pixel. Then I extract the same pixel from the maps, in order of advancing time, to generate one clock. I followed up with a little database that allows me to do this efficiently for several hundred clock sites. The whole thing is a mere 8000 lines of Python."

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Author: Lydia Lousteaux

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