This article first appeared in the Vernal Equinox, 2002 issue of the HORIZON
newsletter of the WCAC.
 

The Rock Hounds
by Dave Gill

If you have humored me over the years by reading the pieces I’ve written for HORIZON, you’ve seen me expound on more than one occasion about the subtle pleasures of astronomical observing.  Amateur astronomy is not for those wanting to be blown away by sensory excess. But I think that my most recent excursion into the realms of observing astronomical phenomena probably has to take the award for being about the most esoteric thing I’ve ever tried to observe.  Yet, it proved to be a most exciting and satisfying hunt, and stretched the observing muscles of all of us who were involved.

It began a little over 2 years ago when a Minor Planet Center Circular was issued:

 “MPC (Minor Planet Circular) 40701.  5391 Emmons = 1985 RE2.
Discovered 1985 September 13 by E.F. Helin at Palomar. Richard Emmons (b. 1919), Emeritus Professor of Physics at Ohio’s Kent State University had his interest in astronomy sparked by an article published soon after the discovery of 1932 HA (now 1862) Apollo. He was an early observer of artificial satellites.”

Now, I’ve never been a big observer of asteroids.  Beyond the “Big Four” and an occasional asteroid occultation, I’ve pretty much ignored them.  But this one was going to be different.  This one was personal. If you check the web page piece I wrote at http://www.twcac.org/onlinehorizon/5391_Emmons.htm , I even opened my big mouth and promised Dick that we would find that little bugger with the 16” Keller scope. It seemed a harmless little promise at the time – heck it was two years off.

Fast forward to 2002.  The day of reckoning was fast approaching.  I talked with Dick about the upcoming event, and he informed me that he had purchased an image intensifying eyepiece, the “I-cubed” piece.  The idea was to brighten up the faint star-like image of his “pet rock” to enable him to see it from his home.  These devices are rather expensive, and he joked that he had to sell a kidney to purchase it.  The eyepiece was hereafter referred to as “Dick’s kidney”.

I updated my orbital elements and started working to make finder charts for the web page and the phantom Summer 2002 HORIZON.  This proved to be a little adventure in itself.  I have three different pieces of planetarium software residing on my laptop – “Starry Night Pro”, “MegaStar” and “Guide 8.0”.  Each has its own strengths and weaknesses, and I like all three for certain things.  By reputation, Guide is the best for doing orbital work with comets and asteroids. Unfortunately, it was the program I had the least experience with.  So, I got to learn it. The results were the charts that are on the web page.

The real power of “Guide” is that it has the ability to plot stars fainter than we can see with the Keller.  It has the Hubble Guide Star catalog stars and you can use Guide to download sections of other catalogs such as the Naval Observatory’s A2 catalog.  So in the process, I learned about plotting asteroid paths, adding reference circles for scale, choosing the magnitude limits and scale sizes for the charts, and how to pick off reference magnitudes, etc.  If you are a serious amateur, I highly recommend “Guide 8.0” to you.  It is only $89, and the author gives great support. I made Dick a set of charts for his use with stars down to 16.0 magnitude, figuring that he wouldn’t be able to see that deep from home.  I was right.  But unfortunately, the asteroid ended up fainter than had been expected as well.

As the date of opposition, around September 8, approached we had to make a formal plan for our assault on 5391. The moon looked favorable for the weekends of the weekends of Aug. 30 and Sept. 6 – especially the latter.  The asteroid was in Aquarius, so we’d have to wait till about midnight for it to be high enough to have a reasonable shot at it.  We decided to try any good night we got.

Dick was already trying from home.  Unfortunately his home site is in the northwest part of North Canton, and is quite light polluted.  But he has a variety of instruments, the kidney and lots of skill and desire. Up to the night of the 30th, he had not found it from home,  plus he added the ominous fact that he had noted a lot of difficulty in finding Pluto over the summer, and it was about as bright as 5391 could be expected to get.

The night of the WCAC meeting on the 30th, we went down after the meeting and fired up the Keller scope.  I had my charts, but had not really studied them yet.  The Keller scope is noted for being a brute to manipulate -  bringing to mind the astronomical parody of Gilbert & Sullivan’s “A British Tar is a Soaring Soul” from HMS Pinafore –

His knees should bend and his neck should curl
    His back should twist and his face should scowl.
    One eye should squint and the other protrude
    And this should be his customary attitude.

(written 1879 by Winslow Upton of the Harvard College Observatory)

It was made worse by my “customary attitude” – tired and frustrated and this time in pain from a foot problem. I was ill-prepared.  The finders were not properly aligned, and I could not even find the right field stars. John and Bill were looking in the Resetar 10” Schmidt-Cass.  They found the field, but could not find the rock.  My magnitude notations suggested that the rock must be in the mid-15’s somewhere.  No one was certain they saw it.  Or even vaguely confident.  We took Dick home, all of us disappointed.

Dick tried more from home, but did not succeed.  Bill Castro tried imaging it from home with his Astrovid, and we thought he captured it.  But my finder charts were a little off, and I later discovered a faint star where the asteroid was thought to be. But the Labor Day holiday meant that Bill & John had another weekend night to practice imaging and sleep deprivation.  This time they used John’s STV camera on the Resetar.  And this time they captured the beastie – even its motion!  Looking at the image confirmed the asteroid to be fainter than expected – probably 15.3 – 15.6.  But it was amazing that John could go that “deep” with a 25 second exposure.

Dick was excited to see the images.  It proved that the fifty-three hundred and ninety first rock from the sun was where it was supposed to be and right on schedule.  He kept trying at home.  On Wednesday evening, Sept. 4, I invited Dick over to my yard to try with my 14” Dob.  (For those of you who don’t know, my 14” mirror used to be Dick’s 14” mirror – I bought it from him in 1991-ish).  We worked at it for quite a while.  I know I had the field, but could not spot the asteroid.  We got out Dick’s kidney and tried some more.

Now this is where things get even trickier.  You see, the I3 piece has a rather narrow field of view to start with.  And it does not come to a focus on my 14” – because of my mirror positioning.  So Dick suggested using a Barlow lens.  It had the desired effect on the focus, but it cut the field down to about 6 arcminutes – really small. In addition the I3 inverts the image, rendering an erect image.  So imagine the scene. I’ve just spent about 45 minutes continually navigating a high power visual field and recovering the asteroid field over and over.  I knew it pretty well.  Then, after midnight, Dick changes the rules on me!  We have to navigate it upside down and backwards with an even smaller field (about 1/3 the size I was using before).  Plus I’ll have to move off of the field we’ve been looking at to focus on a relatively bright star.  Geeeeez.  But, I picked up the skill after a short while and we found the field – minus the asteroid again. We finally gave up about 12:45 am.

Our second weekend of opportunity was upon us.  I invited Dick down to the Public Night at TWC on Sept. 6. It was gloriously clear that night.  I took my 14” down, and I planned on trying the dreaded 16” workout again as well.  We found it with the 14” without much problem.  A number of us, including Dick, Dave Ross, Eric Mast, Bill, John, Jim Quinn and others saw it- mostly intermittently with averted vision. Then Dick pulled the ol’ kidney trick on me again – but this time my experience on Wednesday had made me confident I could navigate the field.  We found it and could see it steadily.

Then we went into the observatory.  While I was starting with the Keller – by aligning the finder – Dick watched as John imaged the field again with his STV. I found the field again in the Keller.  We noted that the asteroid had moved with respect to the background.  That confirmed that we were seeing the right thing.  With the Keller we could see it steadily with regular optics as well as with the kidney – which thank goodness could be used without the Barlow on the Keller.

So, that night Dick and I went home happy – he had seen the eponymous rock that had so far eluded his skilled searches, and I was happy –
1.  Because I found it
2.  Because I kept my promise to Dick, and
3.  Because Dick was happy.

Lessons Learned:
1.  When hunting for faint objects, excellent charts are a must.  Overkill is better than underkill.  The value of a program like Guide or Megastar cannot be overemphasized for making custom charts.  Mark magnitudes of strategic stars both from navigational need and for estimating visual magnitudes.

2. Preparation.  Make a plan for your star hops. Try to draw maps and point out shapes on your charts to aid your star hopping.  Study the field in binoculars before starting with the scope.

3.  Finders – the Keller has a problem with a lousy assortment of finder scopes which suffer from either small aperture or too high power (and thus too small a field).  A good wide field is a necessity.  Be sure the finder is aligned with the optical axis of the telescope.  We believe the Keller flexes, requiring frequent adjustments as we point at different areas of the sky.

4.  Take your time.  Dark adapt – put a hood over your head to block stray light.  Breathe deeply.  Use faint red light if possible for referring to the charts.

Epilog – thus far (as of Sept. 14) Dick has still not captured the rock from home – a combination of the unexpected faintness of the asteroid, the light pollution of his site, and the fact that his big scope (a 17” Dob) has an open tube and is prone to a great deal of light scatter that degrades contrast.

So, Dick, thanks for the fun ride. It was an exciting trip.  We all learned a lot and benefited from the challenge.  Bless your heart (and your kidney, too)!
 


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