Category Archives: What’s Jim doing now?

Jim is always thinking ahead, whether it be planning new observing projects or adding new capabilities to his observatory.

Buying More Aperture

I have written about my bout with aperture fever on this site, and how I overcame the affliction – at least temporarily. To be fair to myself, I did a through assessment of why I bought the Televue NP101 (4″ apochromatic refractor), and I came to terms with why it is a fine instrument. I am by no means abandoning this telescope. It has a place in my collection, and it can do things that the light bucket that I am about to describe could never dream of doing. I expect to use it often for as long as I am able to engage in my hobby.

Please indulge me for one more paragraph before I describe what I am buying. I have also written here about why I bought the NP101 in the first place – I am preparing to enjoy my life-long love of astronomy in my retirement. The acquisition that I am presently pursuing will add another dimension to my enjoyment of my hobby, and to my ability to share my hobby with others. And to be sure, this new instrument can do things that the NP101 can never dream of doing. There is plenty of room for both instruments in my collection.

The telescope that I have ordered is a Meade LX200 12-inch f/8 Schmidt-Cassegrain reflecting telescope. Unlike others I know who have purchased Meade or Celestron Schmidt-Cassegrain reflectors, I chose to forgo the Meade fork-style mount, and chose instead the Losmandy G-11 German equatorial mount (GEM) with the Gemini II goto system.

This telescope weighs 56 pounds, which exceeds the capacity of my Losmandy GM-8. I chose Losmandy mount over a Meade fork-style mount, because I intend to do astrophotography. A fork style mount is simple to use and is great for visual astronomy. It is, however, completely inadequate for astrophotography. This, and my familiarity with Losmandy made the G-11 a natural choice. And since finding objects with an instrument of this focal length (much narrower field of view) will be exceedingly more difficult than with my NP101, I ordered the Gemini II goto system to reduce the amount of time time required for find the object that I might be trying to visually observe or photograph.

I expect to take delivery of the telescope and mount in six to eight weeks. I will not be sharing the news of my telescope’s arrival with my amateur astronomer friends, because they will most undoubtedly hold me accountable for the many cloudy nights that are sure to follow its arrival. Meanwhile, I must maintain my sanity by being calm and forgetting that I have a new telescope on order.

© James R. Johnson, 2016
jim@jrjohnson.net.

 

Testing Kevin’s Camera

I was speaking with Kevin some months ago about astrophotography, and he mentioned that his camera, an Orion StarShoot Solar System IV, did not seem to be working correctly. The two problems that he mentioned were that he could not see the entirety of the moon in a single frame, and that he could not see Jupiter at all. I surmised that there was nothing wrong with the camera, and I explained that video-type planetary imagers like this had notoriously small sensors that have a very narrow field of view. Precisely aligning the telescope to cause Jupiter’s image to fall on the small sensor would therefore be difficult, and this would explain why only a small portion of the moon would be visible. He loaned me his camera for testing, and I have concluded that I was correct about the nature of his problem.

I tested the camera on my C11, and obtained the results seen in the images below, which seem so confirm that the camera was working. As I began to write up the test, I learned that the camera’s sensor format was 1/3-inch. To put this fact into perspective, 6 of these sensors arrayed side by side would be required to span the entire width of the 2-inch rear aperture of the telescope. In other words, the sensor is only 16% as wide as the aperture, which explains why Kevin would not have seen Jupiter in the sensor frame unless its image was almost perfectly centered in the rear aperture.

The focal length of the C11 with a 2x PowerMate is 5600mm. This results in a .14 x .14 arcsecond field of view on each of the camera’s 3.6 x 3.6 micron pixels. I set the camera to a 640 x 480 mode to improve the frame rate, thinking that I was selecting a smaller region of interest, or a subset of the sensor’s pixels at the center of the sensor. What I did not realize is that this binned the output into 2×2 arrays of pixels that would be output as a single 7.2 x 7.2 micron pixel.  This had the effect of halving the resolution that the camera was capable of producing. I would like to be able to repeat this test in the 1280 x 960 mode.

Before mounting the camera on the telescope, I wanted to make certain that Jupiter would be visible on the camera sensor by using eyepieces to center up Jupiter in the field of view. I started with a Panoptic 35mm, which I found very difficult to determine if Jupiter is centered. This is because this eyepiece’s exceptionally wide field of view made it impossible for me to see two opposite sides of the visible field at the same time, so centering at this stage was very much an estimation. Next, I replaced the 35mm with a 17mm Nagler, and repeated the process. It was better, but it was still somewhat difficult to determine if Jupiter was centered with this eyepiece. Next I put in a 12mm crosshair eyepiece, and was able to center up perfectly. When I replaced this eyepiece with the camera, and brought it up on the laptop screen, Jupiter was centered perfectly. Finally, I put the 2x PowerMate in the optical path, and only needed to adjust slightly.

On March 30, 2015, the night of the test, Jupiter’s apparent diameter was 41.6 arcseconds. I used PhotoShop to measure the diameter of the image produced by the combination of the optical configuration and the sensor. The measurement across the center of Jupiter’s white equatorial band was 142 pixels. This compared favorably to the computed prediction of 154 pixels. I attributed the difference between the computed and actual values to me being less than completely careful in taking the measurement and the limb darkening on the disk of Jupiter. Being able to predict the image size  increased my confidence that Kevin’s camera is working just fine.

Just a few words about the clarity of the images as I wrap this up. As I previously mentioned, the resolution of the images could have been improved by using a 1280 x 960 setting instead of 640 x 480, thus doubling the resolution. The night was fairly still and dry, so the “seeing” probably did not affect the image quality very much. Focus seems to be very difficult to achieve while watching video stream off of the sensor, so that could have been a factor affecting image clarity. I made no attempt to rule out focus as a problem by capturing several frame sets while slightly changing the focus each time. And lastly, I believe that the telescope might have some issues, which I believe can be ruled in or out by eliminating focus as an issue.

For good measure, I did a couple of captures on the moon. Clarity, seems to be an issue here too. This did demonstrate that the entirety of the moon’s surface is not likely to be visible in Kevin’s telescope. Note that in the Plato photos, adding the 2x PowerMate magnified the blurriness.

All of the images that follow were lightly processed. I stacked the frames in Registax, and then I adjusted the curve and levels in PhotoShop.

Jupiter 3-30-2015-6
Jupiter by Jim Johnson on March 30, 2014 using a Celestron C11, Televue PowerMate 2x, and an Orion StarShoot Solar System IV.
Moon 3-30-2015-7
Plato and Environs on the Moon by Jim Johnson on March 30, 2014 using a Celestron C11 at prime focus, and an Orion StarShoot Solar System IV.
Moon 3-30-2015-8
Plato and Environs on the Moon by Jim Johnson on March 30, 2014 using a Celestron C11 a PowerMate 2x, and an Orion StarShoot Solar System IV.

 

Moon 3-30-2015-9
Copernicus and Environs on the Moon by Jim Johnson on March 30, 2014 using a Celestron C11 a PowerMate 2x, and an Orion StarShoot Solar System IV.

© James R. Johnson, 2015.
jim@jrjohnson.net

Buying a New Desktop Computer

I have been proudly limping along  and making do with a five year old laptop since I first tried my hand at astrophotography about two years ago. Photoshop, DeepSkyStacker and Registax really take a while to grind out a finished product on the old piece of schist. I am ready to get serious, I mean really, really serious, about astrophotography. Toward this end, I have elected to purchase Mike Unsold’s Images Plus for processing. I noted that this software is capable of using multiple processors, so I researched various processors and architectures. I settled on a Windows 7 x64 desktop box with an Intel CORE i7-4790K on an ASUS H97M-E motherboard with 16GB memory. It will have a 1TB SATA hard drive, and an EVGA GEFORCE GTX750Ti with 2GB onboard RAM. This should do the job quite nicely. Just to be sure that I can see the finer details of my work, I purchased an Asus 23″ VH238 LCD Monitor. The box should be ready to pick up by Wednesday. Hmmm, instead of dragging a 19″, 5-year old flagstone-ish laptop to the field, perhaps I should upgrade this component of my technology suite soon.

Planning a Solar Eclipse Expedition

There will be a total eclipse of the Sun on August, 21, 2017 beginning in Oregon with the Moon’s shadow racing across a thin swath of the United States and ending in South Carolina.  The path of totality will not cross Maryland, so an expedition is required to go see it. I have a telescope, a camera, a Jeep, and a sense of adventure. Why wouldn’t I mount an expedition to see one of the most awe-inspiring astronomical events that humans have ever witnessed? Please check back to this post as I periodically update with specifics as my planning exercise progresses.

March 1, 2015: I begin planning with a few parameters in mind: 1) view the eclipse at the point of the longest period of totality, 2) temper that with finding a point where the weather most likely to be clear, and 3) find a jumping off point where I can quickly shift east or west to avoid cloudy skies.  Of course, driving to Oregon is out of the question, so perhaps any point from say Missouri to South Carolina might be a reasonable target.

March 5, 2015: It is a snowy day in Maryland, which somehow seems an appropriate time to begin working in earnest on an expedition plan for a solar eclipse that will occur on a hot August afternoon almost two and a half years hence. I discovered a great information source: www.eclipse2017.org, and I recommend this Web site for anyone wanting to learn more about this eclipse, or stay current or related developments. Among the things that I learned that makes an expedition an imperative is that my location in Maryland will experience about 85% totality. This will never do!

The the ideal place to view the eclipse is at the longest point of totality (2m44s), which will be in Shawnee National Forest in southern Illinois. Coincidentally, the path of totality within a five-hour drive east or west of this point is in a zone that historically experiences 30% to 40% cloud cover in mid-August. This is much better odds than I can ever get in Maryland.

The initial plan that I have formulated is arrive in Louisville, KY the afternoon before the eclipse. This is a 9-hour/600 mile drive from Maryland, and Shawnee can be reached in another three hours the next morning. Also from Louisville, there are good routes for moving east or west along the path of totality to reach alternate viewing cites if Shawnee is predicted to be clouded over.

March 7, 2015: Looking at east-west options that are reasonably accessible from Louisville, I have selected St Louis, Missouri (4 hours, 250 miles) to the west, and Franklin, Tennessee (5 hours, 380 miles ) to the east the boundaries for selecting alternative viewing sites. I am fairly happy, at least for the moment, to have framed a coincidence of maximum totality, good weather, and accessibility from where I live. Before examining specific viewing sites, I will next work on a viewing plan that can be modified to account for any location that I may elect for viewing the eclipse.

 February 24, 2016: It has been almost a year since I added planning details, but that doesn’t mean that I have not given a considerable amount of thought to the matter. As I add this entry, it is a cold, blustery, and snowy winter’s day in Saint Louis, just over a two-hour drive to the point of the eclipse’s longest duration, just south of Carbondale, IL. I have formulated Eclipse Logistics Plans A and B. Plan A is a drive straight to Carbondale on the day before the eclipse if Carbondale’s weather is promising. I would either view the eclipse from the Southern Illinois University (SIU) campus where the duration is only four seconds less than the eclipse duration at the longest duration point, or drive the six to eight miles required to get exactly on the eclipse center line. Plan B, if Carbondale’s weather outlook is not so promising is to drive to Louisville, KY the day before the eclipse and bed down there. This would require that I wake up at zero-dark-thirty the next morning, assess the best weather prospects either east or west of Carbondale, and drive there leaving sufficient time to set up before the eclipse begins. In the next installment, I will capture my thinking on what equipment to take and how to observe and/or photograph the event.

 

Using WordPress

Heretofore, I have been “hand coding” html pages for Scope Out, and for pretty much anything that I wanted to write and share with readers. Now I have discovered and learned how to use WordPress. It is incredibly easy to develop and publish content, so my limited writing time will be more productive. This post, for instance, took about two minutes to write, and I only need to click “Publish” to make it instantly available.

Rationalizing a GOTO Telescope Mount

I am quickly building an exceptional capability to image wide field objects, some of which appear much larger than the Moon. I hope to someday be be able to engage in a wider spectrum of astrophotography, to include planets, and smaller deep space nebulae and galaxies.

My Losmandy GM-8 mount has the payload capacity to easily handle photography with my TeleVue NP101 4″ refractor along with a guide scope, and two cameras, all of which are best suited for wide field photography because of the main telescope’s short focal length. I could add a goto control panel and servos to this mount for about $1600, but I can find anything that is suitable to be viewed or photographed with this instrument with the technique described in Finding Barnard’s Star. I have a Celestron 11″ reflector that I can put on this mount, but it is so near the mount’s maximum capacity, even before adding a guide scope and cameras, that it is unsuitable for astrophotography. So this set of facts drives the need for a mount with greater capacity, and sticking with the Losmandy line,  with which I am already very comfortable, I will get the Losmandy G-11, which is about $3200 with goto. The Celestron’s longer focal length, and hence its much narrower field of view, and the planetary and exceedingly dim deep space objects that I seek warrants the goto capability.

Before I make that plunge, I need to finish checking out the used Celestron that I bought last year. I took a few shots of Jupiter and Mars in April (all images in this paragraph can be found in the Gallery) that didn’t turn out very well. For comparison, look at the Jupiter and Saturn images that I took with the 4″ NP101 in 2012 and 2013. Dew was a huge problem on the night of the Jupiter pictures I took with the C11. I am hoping that improper focus is the only remaining problem in the Mars picture. Summer set in before I could gain enough experience with this instrument and start the tedious work of eliminating problems. Jupiter is quickly becoming an early evening object again, so I can resume this work in December or January.

I can claim some success with my Jupiter images. The dimensions in pixels in the full res images is almost exactly what I had calculated before taking the photographs, and is what is needed to capture the detail that I am looking for. Check out the Jupiter images that James Willinghan took with a 12″ Meade, and posted to the Howard County Astronomical League (HAL) Facebook page (June 2013) to get some idea of what I am trying to achieve. While you’re there, you check out the progress on the observatory that the club is building in some of the more recent postings. I somehow became the only mug that is clearly identifiable in the banner image. I can also be seen in some of the pictures taken when we cleaned and repaired the dome (Sept 2014), and when we set up the telescope to check out (April 2014) dimensions and clearances required. I have only posted one photo (Nov 2013) on this page so far.

As a last resort after trying everything within my capability to eliminate problems, I will have Marty Cohen at Company Seven check for optical defects, and make needed repairs if the telescope is worth putting more money into. I bought it second hand, and for almost nothing, just to get some experience with reflector telescopes. If the Celestron is not worth saving, then I will buy a new telescope, probably the Meade 12″, at the same time that I buy the new mount.

© James R. Johnson, 2014.
jim@jrjohnson.net

Announcing Outings with the Telescope

I have decided to start a distribution list for sending out alerts to anyone who might wish to join me when I am going out with the telescope. After giving considerable thought to announcing via email, Facebook, and Twitter, I landed on mobile text.  This method, I believe, will be easiest for me to use, is used by more people than any other communication channel, and a text message is likely to get noticed sooner than one sent by any other means. My initial thinking is that I will project a possible event about two days ahead of a night that I am available and the forecast predicts clear weather, and then send a follow up confirmation early the evening that I am going out. Please let me know if you would like to be added to my alert list.

Getting over Aperture Fever

Fall weather brings clearer skies and earlier darkness, so I have been fortunate enough to get out in the field a couple of times with a telescope and binoculars. The most important thing that I have seen lately is the Milky Way, which I have been prevented from seeing by less than completely clear, light-polluted skies in my backyard observatory. I caught aperture fever at one of the Howard Astronomical League’s dark site star parties, but I quickly got over it.

Aperture fever, a condition that can easily drain the wallets and bank accounts of amateur astronomers, occurs upon realization that more aperture is never enough. On one particular night, I was out with my TeleVue NP101 4″ aperture refractor, and three other club members were set up adjacent to me. I was at one end of the line with my 4″ aperture refractor, Garry was next with a 10″ reflector, then Chris with an 18″ reflector, and finally Mark was at the other end of the line with a 24″ reflector. We did a comparative analysis of three objects through all four telescopes: the Hercules Cluster (M13), The Ring Nebula (M57), and the Andromeda Galaxy (M31). Although I could see, and have even photographed all three objects, with my telescope, the difference that could be easily seen in moving up the aperture scale from 4″ to 24″ was astounding at every step of the way in the brightness, and the amount of detail that could be resolved.

By the next morning, I had pretty much gotten over the fever. To be sure, the bigger telescopes can outperform mine in certain ways, but guess what? My 4″ can do things that their larger scopes can never dream of doing. With its wider field of view, my telescope can easily capture in a single image large scale objects, like the Andromeda Galaxy, North America Nebula, and many others. Their larger aperture, but narrower field of view telescopes could only painstakingly capture these objects with multi-image mosaics. Although still a novice astrophotographer, I have been able to capture some pretty nice images of these objects with this modest telescope.

For now, I continue to be happy with the fine instrument that I have, and I expect that it will be years before I have accomplished all that is possible with it, and there will be some events like close conjunctions of planets for which my telescope will be better suited than theirs. I plan to augment my wide field imaging capability in the near future by purchasing some camera lenses that can capture even wider fields of view.

What I especially want to share with my stargazer friends is that there is no “best” telescope for everything.  For a prospective telescope buyer, I would recommend doing some research, and settling on some specific interests, and picking a telescope that is suited to that interest.

© James R. Johnson, 2014.
jim@jrjohnson.net

Planning to Build an Observatory

I decided that I will build a backyard observatory. My reason for wanting an observatory is pretty typical of why any amateur astronomer builds one. Having to set up in the field for every observing session consumes considerable time dragging equipment out, assembling and configuring it for the session, and getting a precise polar alignment for photography. At my skill level, this could take two hours, and I still might not be satisfied with the alignment when I finally throw in the towel. An observatory changes everything! I would be able to walk in, open the roof, turn things on, and I’m ready to observe or image in five or ten minutes. The equipment is always there, and only needs minor configuration before use, and an excruciatingly precise polar alignment is preserved from session to session.  Still researching piers…steel on concrete vs all concrete, building type, electrical considerations and several other details. I will probably settle, and break ground when it gets a little warmer.

Trying out a used Celestron C11

In January 2014, I made it another step closer to becoming one of those amateur astronomers who has x number of telescopes…that his wife knows about. Celestron marketed the C11 Ultima, a 280mm f/10 telescope, in the mid-1990s, and I picked one up second hand at Hands on Optics for a very reasonable price. And by the way, I recommend that anyone interested in a telescope or binoculars stop in and see Gary Hand, because you never know what you might find there. The telescope had been installed in an observatory, and as a result it was somewhat exposed to the elements for a number of years and it needed some work. I cleaned the exterior surface with a premium car polish, and it looks as good a new with the exception of some minor scratches. The V-style dovetail plate was loose because the attachment screws were too long, and therefore would not tighten. I was able to easily repair this. In the short term, I wanted access to a larger SCT reflector to gain experience with a longer focal length and bigger aperture instrument, and to learn how to collimate a reflector. I have been able to take it out just once, and I can see that I have a lot to learn. In the longer term, there may be some potential for more work on the the telescope. I doubt that the mirrors have ever been resurfaced, so that is a possibility. The multicoating on the corrector plate glass is in pretty bad shape. I hear that this is an expensive repair, so I might just have to live with it. And finally, I may install a cooling fan, which will help the telescope reach an equilibrium temperature with the outside air faster. The telescope weighs 22 lbs. Since this approaches the maximum capacity of my mount, I am already thinking about my next major purchase.

© James R. Johnson, 2014.
jim@jrjohnson.net