Article Last revised: 07/24/06 Astronomy

   Pluto Challenge: FAQ   

Revision Notes:

6/03/01: Created.   2/28/02: Minor edits

Frequently Asked Questions for the Pluto Imaging Challenge

Why is this a "Challenge"? Pluto should be easily imaged with a modern amateur CCD camera, in every type of light pollution, with amateur scopes down to 3" or less.

The impetus for the Challenge is the lack of small-scope Pluto images on the web.  With all the deep magnitude claims made by modern amateur imagers, I thought that strange. "Challenge" as used here can be taken as "contest" or "experiment".

Before the Pluto Challenge, my search of the web turned up Pluto images made with 8"-10" (200-250-mm) telescopes -- nothing smaller. So the 3" (80-mm) refractor CCD image submitted during the year 2000 Challenge experimentally proves the viability of CCDs and 3" telescopes. Now, let's find out how much smaller a scope and CCD will image the planet.

Now, consider the contest element of the Challenge. Would we ever cancel the Olympic Marathon under the pretext that "it has been done before." Like the marathon, the point here is to see who can do it the "best" within the rules. The "best" for this Challenge is to capture Pluto in the smallest aperture instrument.

Finally, the sole purpose of all amateur activity is the reward of accomplishing a goal. Think about it: any decent observatory can best anything an amateur can do! Amateurs are rethreading the same ground when they image the moon and planets, before moving onto deep sky imaging -- yet it doesn't stop them. To quote a Pluto Challenge imager: "The experience of imaging Pluto was one of the most rewarding events I've had in astronomy." From that imager's location, there is a constant artificial twilight caused by New York City and the sprawling suburbs. This was the last place I'd expect an entry from. Now, that entry will inspire those in like locations to make images they thought were not available to them.

This particular Challenge will not end until the days comes when Pluto can be imaged with a "pinhole" camera in a single short exposure; at that point, I would agree, that there is no real Challenge. Note that this Challenge is also for film-based images -- I couldn't find one amateur image of Pluto made on film -- I'd like to see what film could do.

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Shouldn't the true challenge be to see who could visually detect Pluto in the smallest aperture telescope?

I don't see the conceptual difference between a visual challenge and an imaging challenge. If it is a valid contest to "find the smallest telescope that a particular person can visually spot Pluto in", given the viewing condition, then why can't we continue down the aperture scale using an imaging instrument other than the eye? At least the imaging offers proof. If someone posts "I see Pluto in a 50-mm" what can we say?

One of the points of the Pluto Imaging Challenge is to demonstrate how far astro imaging has come in a century. I've been reading these past few years that, with the advent of cheap CCD and computer processing, amateur equipment can do "real" astronomy in specific areas. A small aperture challenge will serve to see how small the equipment "envelope" can be pushed. For instance, I get the asteroid and lunar occultation alerts by e-mail. The sponsoring organizations desire observers spread out across designated zones to record the event. But, the predicted occultation path often shifts, as orbital refinements are made up to the time of the event. As a result, the organizers don't always get the coverage they'd like. I think the ability for the observers to travel to observing zones is inversely proportional to the bulk and weight of their equipment. So, these small scope "Challenges" will give observers some insight into imaging situations where a small scope will do fine for the requisite task.

Rebuttal: Sky and Telescope magazine held a real challenge where an amateur imaged down to 22-23 magnitudes in light pollution.

It's great that some amateur, somewhere with the right equipment can image down to "pro" magnitudes, but what makes this Pluto Challenges interesting is the constraint (small aperture) and being pleasantly surprised at how the participants overcome them. I can't see how the "Magnitude Challenge" is any more real than the "Pluto Challenge".

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If I have a big telescope, why should I stop it down to enter the Challenge? This is like having a deep sky photo contest with the worst performing film!

While watching the Olympic swim races, I noticed they gave the medal to the competitor that finished in the smallest amount of time. "Shortest time" is the "Challenge" the athletes must meet in most of those competitions. My Pluto Imaging Challenge is analogous to this, in requiring that Pluto be imaged with the "smallest aperture" telescope. Of course, there are challenges that go the other way time-wise: for the "longest time" one can sit in a tree, ride a roller coaster, or stay awake, etc. Setting up the Pluto Challenge to image the planet in the "largest aperture" scope would not entice many amateurs to enter.

The nature of the Challenge would point toward using the finest films/CCD and lens possible, due to the small aperture constraint. Only those with the luxury of large aperture can overcome the deficit of employ the "worst" film.

Rebuttal: The shortest swimming times means maximum, and the swimmers did not have to swim with an arm tied behind their backs.

The swimmers are constrained by the type of swimming style for that event -- that is the challenge of the various races. The "freestyle" is the fastest form of swimming but is only employed in a few races. Auto racing and sailing are also competitions where the rules limit equipment size for various classes of events. It is not unusual at all to have constraints of this sort in competition.

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Why the highest quality CCD coupled to the weakest telescope? Larger telescopes cost more money but so do high-end CCD cameras. So what is the difference? The fact is that aperture is paramount and should be fully utilized.

I'm not challenging scopes here, but modern CCD/film cameras and post-processing equipment/techniques. Large scopes and film imaged Pluto 7-decades ago, and we know they still can. As CCDs have become cheaper, they have moved from large scopes to smaller scopes. The Pluto Challenge's sample image section has Pluto images from 8"-10" scopes, to demonstrate what that class of scope is capable of. I'm interested in the next step: when CCDs become more common on sub-8" scopes.

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Is it fair to stop-down a big telescope in order to enter the Challenge? 

There may be one advantage of stopping down a big scope to smaller aperture -- as opposed to just using a small scope of that aperture: resolving power.

Say you wanted to stop down a 14" telescope to 4". Starting with a 14" diameter mask: you could cutout 4-circles, with 2" diameters, at 90-deg intervals, along the extreme edges of the mask. Voila! You now have the light grasp of a full 4", with the resolving power of a 14"! This would make Pluto easier to resolve if it were near another star. Anyone stopping down this way should note that down when submitting entries to the Challenge.  I'd like to know if it makes a difference.

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