About Me... My equipment... My Observing Site etc.

   I'm a retired physician with an undergraduate background in math and the physical sciences.  As a kid I was fascinated by natural science... especially by fossils, pond life under the microscope, and rocks.  I grew up in the Apollo years.  Missions to the moon really got my attention.  In highschool I got my first real telescope (a Towa 60 mm aperture FL=910 mm, F15 achromat on a GEM, sold by Sears). 

That telescope was first trained on the moon and it is the moon that has mainly held my interest over the years.  In the early 90's I became fascinated by data acquired by the Clementine lunar probe and set a personal goal of trying to learn more about how mineral composition on the moon could be studied from spectral imaging.  With no formal training in the area, this took some time.  I am very appreciative of the many publications of Professor Carle Pieters of Brown University since they opened up this world to me which otherwise would have remained a complete mystery.  The most influencial of these on me was her Chapter 14 on lunar reflectance spectroscopy in her book Remote Geochemical Analysis: Elemental and Mineralogical Composition (1993).  I've read it so many times that the pages are tattered. I acquired several excellent telescopes and mounts over the years that serve well.   Until retirement there was little free time.  Even so, after joining the Geological Lunar Research group, I made progress in lunar imaging and lunar geologic studies.

Although I had planned to spend a few more years working full time in my profession, the recent death of an old friend from cancer caused me to re-examine my timetable.  Cancer deprived my colleague of any sort of retirement or the ability to devote time to family or to accomplish personal goals.  As I watched this tragedy unfold, it became clear to me that we have to consciously set aside enough time for things that are important to us.  Otherwise there is the risk that time may run out unexpectedly or health might decline.  So, I have set aside some years (hopefully) to pursue a few personal projects that require more time than the workplace would have allowed.  I'd like to become more fluent in French and travel to Quebec more often, hone some math skills (particularly in matrix algebra and SVD) useful in my lunar geologic studies, use my observatory more often, maybe do a little writing, and definitely spend more time with family.

My observatory:

       I've spent the last couple of years setting up a small roll-out shed type observatory and landscaping an observing patio with an excellent sky view.   Although very stable and a pleasure to work on, the brick surface does have the drawback that it retains and radiates heat on hot summer days which can add some ground turbulence to the seeing conditions for a few hours after sunset.  I find that using the adjacent grass or wetting the brick and allowing the water to evaporate away completely before setting up the mount minimizes this problem which can cause loss of image sharpness in hot summer months.  The evaporation process cools the brick surface substantially.  I usually prefer the brick surface to grass because I think it is less likely to harbor the ticks that often carry Lyme disease in my area of New England.

     My observing site and seeing conditions:

    The average ecliptic altitude seeing at my observing site at about 42.6 N, 71.8 W is about 2.5 arc seconds based on FWHM measurements of stars and only exceptional nights approach 1 arc second seeing.  Seeing at the zenith is a bit better.  It is a difficult location for high resolution lunar/planetary imaging.  Most of the time the Canadian/Northern US jet stream sits squarely over my small state of Massachusetts in New England... but occasionally it does leave the area.  From my mid-northern latitude, the ecliptic is much lower in the sky than at the equator and this means that I have to image through a lot more atmospheric air mass with its resulting degredation in seeing.  I am reconciled to my mostly poor seeing conditions and just do the best I can.  But, a few times a year conditions are good enough that I can at least attempt the imaging miracles that amateurs at better latitudes and with better seeing achieve much more regularly.  One of my personal goals for many years was to see the rille on the Alpine Valley floor with one of my scopes.  I've never achieved any more than a glimpse of parts of it visually, but did manage to record most of it with a webcam on a night of good seeing in April 2008 with my Mewlon 250 mm scope.

                     Alpine Valley central rille.  Mewlon 250 FL=6000 mm. Lu075M camera.

     What is the best lunar/planetary scope and camera?  The first thing a lunar or planetary imager using a reflector telescope needs to do is to collimate his instrument.  See this link for a detailed description of the process: http://legault.club.fr/collim.html .  If the telescope is not collimated very rigorously at each imaging session to the precise degree described in this link, then no good results can be expected at all with a reflector of any type and all images will look mushy and lack crispness of detail.  If you don't want to do this, then get a medium sized refractor.  The most important part of collimation is to finish up with attaining a symmetrical 1st diffraction ring around the Airy disk with the star in perfect focus at very high power (500-600x for a 9.25 inch SCT) or as close to this as possible, but it is important to realize that the diffraction ring will only be present and complete in very steady seeing (see:  http://calgary.rasc.ca/seeing.htm  which is an invaluable guide to the effects of seeing on the Airy disc).  A simple 1/20th turn of a collimation screw in the right direction has the same effect on a focused image as turning the focusing knob from a blurred to a sharp image.  But an in a poorly collimated scope, no turning of the focusing knob can produce a crisp image.  One of my recent images of  Jupiter was taken September 7, 2009 at about 0130 UT with the Mewlon 250 at F18 and DMK31 monochrome camera using R, G, and B filters and is shown below.  The mirror back cover of the Mewlon was removed for cooldown and left open during imaging. 

     Planetary imaging is much different than lunar imaging.  You can collect extremely long avi clips of the moon (up to at least 11,000 frames at 60 fps) because it doesn't rotate relative to the Earth (although shadow lengths do change with time).  And so, collecting enough good frames is usually easy enough in good seeing.  And the moon has plenty of contrast.  Camera gain is almost always set low for lunar imaging but set fairly high for planetary imaging.  With Jupiter, you can only collect frames for 120 to 150 seconds maximum (i.e. 40 to 50 seconds maximum per R, G, B channel) because of rotation of the planet.  Planets are small and imaging is best at about F24 to F36 or higher if the seeing allows it.  And, the shutter speed shouldn't lag behind the frame transfer rate or fewer frames will be collected.  Since gamma should be left at 1.0, this means that a larger scope is needed to capture enough photons to have a decent image histogram (at least an 8 to 10 inch reflector for really impressive images).  Then there is the question of whether to use a sensitive monochrome camera for RGB filter imaging or to use a necessarily less sensitive color camera (because the chip has to hold R, G and B pixels).  If you only have 150 seconds to image before rotational blur sets in for Jupiter, then RGB images can  have 3000 frames for each channel at 60 fps and you likely have to re-focus slightly for each filter which takes up a bit of the precious time.  But, the monochrome camera will capture with higher resolution.  With a color camera you can capture 9000 frames at 60 fps but with less resolution.  How will the two different results compare?  It depends on how good the seeing is and what the sensitivity and noise of the cameras is.  It is a personal choice.  For lunar imaging, a monochrome camera of high sensitivity and low noise would appear to be the best choice.  Most high resolution lunar images are taken in black and white.  If you plan to use a refractor for awe inspiring lunar and planetary images, then most likely you are looking at a good quality apochromatic 6 inch or much better yet, an 8 inch refractor... quite an expensive proposition and requiring a pretty sturdy mount.

    My telescopes, mounts, and cameras:

     My main imaging scope is a Mewlon 250 on an EM-200 mount.  My sharpest  images so far show 1.0 - 1.4 km crater resolution and for fine linear structures I've managed to image most of the extent of the Hadley Rille and the more difficult Alpine Valley rille.  I use a Celestron 9.25" scope on a Meade LXD75 mount for filter imaging and spectral work because it has lots of available backfocus.  My other imaging scopes are an OMC300 subaperture maksutov cassegrain (Orion Optics, England) and a Gladius 315  Dall Kirkham scope (Lazzarotti Optics, Italy).  I recently finished a small roll-out type observatory for the Gladius 315 on a Losmandy G11 Gemini mount. The Gladius has a focal length of 7875 mm, has 20% central obstruction, and weighs 11.6  kg.  This setup could become my primary lunar imaging platform on nights of exceptional seeing.  It is an F25 scope and it isn't really designed to image at shorter focal lengths which are often necessary on nights of average or below average seeing.  So, at my location in New England, the Mewlon may remain my most used imaging scope after all...

            Gladius 315/Losmandy G11G  Mewlon 250/Takahashi EM-200               OMC300/Takahashi EM-200

The  OMC300 can produce very good lunar images but achieving focus at the best focal length using standard accessories can be a bit tricky and frustrating, especially if the camera or barlow are changed or a filter wheel is added.  The handmade OMC300 is not nearly as forgiving to use for imaging as more common mass-produced Schmidt-Cassegrain scopes of comparable aperture.   I generally prefer to use the Mewlon 250 for imaging and it seems well suited to my local seeing conditions.  My Celestron 9.25 inch (235 mm) F10 scope can also be used for imaging, but while it is the easiest of all of my scopes to focus, mirror shift is inherent in the design and is really annoying at high power. 

     I also have a 5 inch Meade ED doublet "semi-apochromatic" refractor, but it excels mainly at visual work and can't really compete with my other scopes for imaging. Recently half the street lights in my city were shut down to save the city money in an economic recession. This has resulted in much darker skies, so I've also been doing a bit more deep sky work using a 4.7 inch F5 achromat with an 80 mm guidescope and my Losmandy G11 Gemini mount.  The achromat has its limitations but should be fine for H-alpha and narrow band imaging of deep sky objects.  I had previously often used a 5 inch F6.3 Celestron SCT (with a focal reducer in place)  for deep sky work, but I've given that beautiful little scope (along with my Meade DSI) to an old friend and must now put up with a little chromatic aberration inherent in my wide field achromat. 

     For lunar and planetary work, I usually use a Lumenera 075M camera (640 x 480 pixels, 7.4 micron pixels, 60 fps) but sometimes also use DMK cameras (i.e. DMK21 at 640 x 480 pixels, 60 fps, 5.6 micron pixel size; DMK 31 at 1024 x 768 pixels, 30 fps and the DMK 41 at 1280 x 960 pixels, 15 fps... both with 4.65 x 4.65 micron pixels) and also a Philips ToUcam Pro color webcam.  The smaller a cameras pixels are, the larger the image of the planet will appear on the CCD chip.  Large CCD chips do not improve resolution, they only allow a larger area to be imaged.  I also use a NIR camera, the Su320-mx for filter imaging out to about 1600 or 1700 nm.  My cameras useful for deep sky work include a Starlight Xpress SXV-7 camera which can be used as either an imager or an autoguider, a Lumenera 075M camera useful as an autoguider, a Watec 120N ultra light sensitive videocam, a Meade LPI which is somewhat useful as an autoguider for use with brighter stars, and several Canon DSLRs (Rebel, D20a, and D4) which can be used as imagers through the telescope or using various telephoto lenses.  For image capture software, I currently use AMCAP and IC-Capture for lunar and planetary work and Maxim DL for deep sky work. For image processing software I use Registax 5.0, Ninox, AIP4WIN, IRIS and Photoshop CS2 for lunar and planetary work.  For deep sky work I use Registar and Photoshop CS2.

         I'm still working on my deep sky imaging setup which for the time being consists of a 4.7 inch F5 (FL=600 mm) achromat (not an ED or a semi-apo !) with an 80 mm F5 guidescope that can be used on either my EM-200 or my G11 Gemini mount.  For primary imagers I'm using my Canon EOS Rebel XT, D20a, and D5 DSLR cameras.  The G11 mount without an autoguider allows 5 minute subexposures at FL=900 mm (using a 1.5x barlow) and this is about the limit of what my light polluted city skies will tolerate.  If I eventually move to higher focal lengths, it will be necessary to use my Starlight Xpress SXV-7 CCD camera as an autoguider.  Meanwhile I'm trying to tame the chromatic aberration of my inexpensive but fast achromat with post-processing.  Noel Carboni's Astronomy Tools for Photoshop has many good subroutines including violet halo removal and star size reduction. A FocusMagic plug-in for Photoshop is also very good for removing very small amounts of star trailing caused by minor tracking errors.  So far, the achromat is providing pretty good deep sky images after post-processing and for the time being there is still quite a bit to learn before thinking of moving up to an expensive apochromat.  Below is my scope setup and the resulting image of the Dumbell Nebula in Vulpecula (M27) that I took on October 5, 2009.   I used the achromat with a 1.5x barlow for FL=900 mm and my Canon Rebel XT DSLR camera at ISO=1600 for a 15 minute exposure divided into 5 sub-exposures.  I used the same setup without the barlow (FL=600 mm) for the image of the Andromeda Galaxy taken on October 10, 2009 (sky transparency well below average).

                                                  Orion 120 mm (4.7 inch) F5 achromat on Losmandy G11 mount

     M27. 120 mm achromat at FL=900 mm. Stack of five unguided 3 minute exposures, Canon Rebel DSLR, ISO=1600

              Andromeda Galaxy (M31) 120 mm F5 achromat, Canon Rebel ISO=1600. 3 min x 10. FL=600 mm.

     I'll end by saying that interested amateurs would do well to join an organization specializing in their main area of interest.  The Lunar Geological Research group has enabled me to do serious lunar work approaching the professional level at this point... and the friends that I have made there will last a lifetime...  A couple of leaders in the GLR group have made quite an impression on me and have become good friends and mentors over time. If you are interested, then see their webpages at:

     http://digilander.libero.it/gibbidomine/ 

    http://www.christian-woehler.de/index_e.html

Rick Evans