My New PST for Observing the Sun

Which view of the sun would you rather have? On the bottom is a photoI took during the 1999 Mercury transit, using a 3.5 Questar, one of the best Maksutov-Cassegrain telescopes available. It is a great shot, but besides tiny Mercury, all you see is a nice complex of sunspots. The problem is that even with the excellent filter of the Questar, you are looking at the sun in White Light. In order to see solar prominences and filaments you have to look at the sun in H-Alpha.

The other photo is one I took this week using a new telescope.

Questar does a nice job with sun spots, but I wanted to see prominences, filaments, plage and flares -- and sunspots. The picture below was found on www.coronadofilters.com.

Coronado produces PSTs, or Personal Solar Telescopes-- a wonderful telescope for solar viewing.

PSTs allow a person to view the sun in the H-Alpha bandwidth of the spectrum. Questar offered an H-Alpha filter. The only problem is that it costs about $6,000 to add this to an existing Questar telescope.

Coronado offers a much more affordable option. Their PSTs don't have a lot of power and magnification, but when looking at the sun it is not magnification you need as much as the filter.

I ordered one of these PSTs. It came on Monday.

I woke up on Monday, knowing it would arrive sometime during the day, and was distressed to see the gray clouds covering the sky. But by 9 AM, the sky went from cloudy to clear blue within a short time -- like a curtain being opened.

I had a chance to spend a couple of hours playing with my new toy.

The PST is simple to use. The instruction manual is really just a small single sheet, making a tri-fold pamphlet. There is not much to know about how to use it. However, I did come to appreciate what the tiny instruction manual meant when it said, "It can take time to 'train' one's eye for H-Alpha viewing." My first reaction to looking through the telescope was disappointment. All I saw was an orange-red sphere. It took a while to understand how to look through the new telescope.

The PST is simple to use, even more so that a Questar. When I use the Questar to look at the sun, I have to screw in the solar filter and remember to flip the hinge operated, built-in solar filter over the view finder. (Johnny Carson is responsible for that addition to Questar. He was an avid astronomer and when he bought his Questar in the early 1960's he personally complained about the danger of not having a built in solar filter for the view finder).

With the PST, the filter is built in. Period.

Coronado has also come up with a special view finder. There is a pinhole-size opening in the base of the telescope that reflects the sun's image on a screen.

After putting it on the tripod, I located the sun using a special view finder Coronado has devised.

As you can see in the picture above, the tiny, circular screen shows a tiny solar image. Center that and the sun should be visible in the eyepiece. It is handy, in that you can move the telescope's position and look through the eyepiece while keeping the other eye open to look at the view finder screen.

The focus knob, shown here, is conveniently located. To focus the PST, don't look at the body of the sun, but along the limb. When the limb is sharp, the telescope is in focus.

My initial disapointment is that nothing came into view once I focused the telescope.

The instructions provided by Coronado says that there is another important adjustment the observer can make, in addition to focusing.

It is a knob encircling the tube of the telescope called the tuner -- something not found on other telescopes. It rotates or tunes the filter. Coronado adjusts this at their factory and says that you normally would never need to adjust the tuner. After several minutes of being frustrated with nothing to really see, I dared to adjust the tuner.

Everything came into view! There were prominences and filiments all over the surface of the sun. The entire sun had a distinct texture to it.

This telescope was reviewed in Sky and Telescope magazine a year or two ago, and the reviewer's main criticism is what Coronado calls the "sweet spot." When the telescope is tuned and focused, the eye will see filiments and prominences in the "sweet spot" of the eyepiece. As the earth turns and the sun seems to move out of the view of the telescope, those solar features will appear to grow and then disappear.

It takes a while to become accustomed to the sweet spot, and I don't pretend that I have gotten used to it after only two days.

The closest I can compare it with is looking at Andromeda Galaxy, M-31. That dark sky object is visible with the unaided eye -- or was before all the street lights were set up. Even in a rather small telescope, the image is so large that the best way to look at it is to turn off the clock-drive and let the earth's rotation turn the telescope so that the image slowly comes into and then out of view while the observer just sits there and watches the show.

Setting the telescope on the edge of the sun the observer can watch the sun come in and then out of view. The sweet spot will highlight different features on the face of the sun.

It is taking some time to master photography with the PST -- this image here is my very first attempt. It shows a prominence along the limb, or edge, of the sun, but it doesn't to justice to what I actually saw. The more recent photos are a vast improvement over this first try.

The PST comes with a single eyepiece, a 20mm (20x) 1.25" Kellner. I added a 2x Barlow and enjoyed the viewing much more with the increased power. Coronado recommends buying their eyepieces, but I found that any of my 1.25" occulars were good.

Amateur astronomers are not usually as interested in magnification as the general public, because there are other things more important to us, such as resolution. Still, the question is a good one -- what is the magnifying power of the PST?

The formula to calculate a telescope's magnification power is M= fe/fo, or magnifcation equals fe, which is the focal length of the eyepiece, divided by fo, which is the focal length of the objective lense. The PST has a focal length of 400mm. Using the 20mm eyepiece, that is a small magnification power of only 20x. The barlow I have is a 2x, which increases the power by having a deminishing effect on the eyepiece focal length. In other words, the 2omm eyepiece with a barlow becomes a 10mm eyepiece -- resulting in a magnification of 40. It is still small, but sufficient for the sun. I have a 12.5mm eyepiece, which is the smallest I have -- so with a 2x barlow, that becomes a 8.25mm for a power of roughly 48.5. That's quite a bit different from the magnification of my 3.5 Questar, with which I can achieve a magnification of about 360x, or the 10 inch reflector I have that can reach about the same, but captures more light.

But I digress.

Getting back to the PST, I was particularly pleased with the video images I took using a Meade electronic eyepiece -- it has a 320x240 pixel CMOS monocrome imaging sensor. Even though it records the image in black and white, the detail of the image was better than I was able to get on the first several tries I made with the digital still-camera.

Last night was a clear night, so I continued to take a few photos of the from Arp's Atlas of Peculiar Galaxies. Below is Arp 049, NGC 7545. The duration of the image was ten minutes, and it still is a bit of a disappointment.

Next is Arp 28, NGC 7678.

NGC7678 is a face-on spiral galaxy in Pegasus. it has an arm that is nearly as massive as the rest of the galaxy, which I believe is why Arp included it in his list.


Arp Galaxy 337

Finally -- a galaxy in Arp's list that is actually bright and easy to see -- but still it meets Arp's criteria that it is a "peculiar" galaxy.

NGC 3034 is bright enough to be in Charles Messier's catalog as M82. It is often referred to as the "Cigar Galaxy" and it certainly appears to deserve its name.

M81 and its neighbor M82 form a striking pair in the small telescope. M82 is being physically affected by its bigger neighbor. Tidal forces caused by gravity have deformed th eM81 galaxy, a process that started roughly 100 million years ago. This interaction has caused star formation to increase 10 fold compared to "normal" galaxies. At present the centers of M81 and M82 are about 150,000 light-years apart.

Here is a photo I took of M81 a few years ago.

M82 is the type example of an Irr-II -- Irregular galaxy type II, meaning the disk is irregular. Recent studies, however, suggest that it may actually be a barred spiral galaxy seen edge on from earth.

Of course, as good as I think I did, NASA did better with the Hubble Space Telescope!

Observation notes:
2006 September 16, 23 hours 02 minutes local time.
Sky -- excellent. 4 out of 5. Dark sky.
5 minute exposure on 3 megapixel CCD.
14 inch Schmidt Cassegrain Telescope with 3910mm focal length.

Stephen's Quintet -- Arp Peculiar Galaxy # 319

Stephen's Quintet is another very tough challenge to find and photograph.

The quintet is a prototype of a class of objects known as compact groups of galaxies and has been studied intensively for decades.

As its name implies this is a group of five galaxies (NGC7317, 7318A, 7318B, 7319 and 7320) and lies about 270 million light-years away in the constellation of Pegasus (North-west of the Great Square of Pegasus).

The galaxy group discovered by the French astronomer Edouard Stephan in 1877, using the Foucault 80-cm reflector at the Marseilles Observatory -- and it was the first such grouping to be found. Today we know of hundreds of similar groupings, but few are as spectacular as Stephan's Quintet.

Observation notes:
2006 September 16, 19 hours 37 minutes local time.
Sky -- excellent. 4 out of 5. Dark sky.
5 minute exposure on 3 megapixel CCD.
14 inch Schmidt Cassegrain Telescope with 3910mm focal length.

Arp Galaxy 728

The Arp galaxies are often so dim, that a slight improvement in the skies can do wonders!

The top image was taken on September 4th, with a 12 day moon -- pretty close to full. The bottom image was taken on September 16th, with a 24 day moon -- still fairly bright, but not so bad.

The galaxy has a "V" shape to it.

This pair of 14th-magnitude galaxies lies in northwestern Pegasus, about 200 million light-years away. In the image, NGC 7253 B is the larger galaxy nearer the top, and NGC 7253 A is the smaller one, apparently on the bottom from this view point.

Observation notes:
2006 September 16, 22 hours 52 minutes local time.
Sky -- excellent. 4.5 out of 5. Dark sky.
5 minute exposure on 3 megapixel CCD.
14 inch Schmidt Cassegrain Telescope with 3910mm focal length.

Arp Peculiar Galaxy # 225

I should visit this galaxy again later on -- I simply did not get a good image tonight. It is a 3 minute exposure and it needed a longer period.

Observation notes:
2006 September 16, 20 hours 15 minutes local time.
Sky -- excellent. 4 out of 5. Dark sky. No moon.
5 minute exposure on 3 megapixel CCD.
14 inch Schmidt Cassegrain Telescope with 3910mm focal length.

Arp Peculiar Galaxy # 169

Arp 169 is a triplet of galaxies -- NGC 7236 and 7237. The are tough objects to find. The photo I took is a very poor quality. The pair is the fuzzy stars in the extreme left center. I know -- all of the stars in this image are fuzzy. NGC 7237C, the third of this group, is beyond my eyes or my imaging equipment.

I have inverted the image so the galaxies stand out a bit.

Observation notes:
2006 September 16, 19 hours 30 minutes local time.
Sky -- excellent. 4 out of 5. Dark sky. No moon.
5 minute exposure on 3 megapixel CCD.
14 inch Schmidt Cassegrain Telescope with 3910mm focal length.

Arp Peculiar Galaxy # 112

Arp 112 is a very dim, difficult galaxy to photograph. It is more commonly known as NGC 7805 and NGC 7806. NGC 7806 is particularly dim. Because this pair is so dim, I am only posting an inverted image. The fuzzy star next to NGC 7805 is simply that, a star that simply appears fuzzy.

Observation notes:
2006 September 16, 21 hours 50 minutes local time.
Sky -- excellent. 4 out of 5. Dark sky. No moon.
5 minute exposure on 3 megapixel CCD.
14 inch Schmidt Cassegrain Telescope with 3910mm focal length.

Arp Peculiar Galaxy # 86

The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp. These 338 interesting and often challenging deep sky objects are more commonly called ARP galaxies.

Arp realized that the reason why galaxies formed into their usual shapes of spiral or elliptical patterns was not understood by astronomers. With this atlas, astronomers had a sample of peculiar galaxies that they could study in more detail. The atlas is not a complete overview of every peculiar galaxy in the sky and does not intend to be -- but it does provide examples of the different phenomena as observed in nearby galaxies.

Because little was known at the time of publication about the physical processes that caused the different shapes, the galaxies in the atlas are sorted based on their appearance.

Objects 1-102 are individual peculiar spiral galaxies or spiral galaxies that apparently have small companions.

Objects 102-145 are elliptical and elliptical-like galaxies.

Objects 146-268 are individual or groups of galaxies with neither elliptical nor spiral shapes.

Objects 269-327 are double galaxies.

Finally, objects that simply do not fit into any of the above categories are listed as objects 332-338.

Most objects are best known by their other NGC numbers, Messier numbers or other catalogue listing, but a few galaxies are best known by their Arp numbers, such as Arp 220.

There is better understanding today about the physical processes that lead to the peculiarities seen in the Arp atlas. A large number of the objects are interacting galaxies, including Arp 85, Arp 220, and Arp 244.

A few of the galaxies are simply dwarf galaxies that do not have enough mass to produce enough gravity to allow the galaxies to form any cohesive structure. NGC 1569 or Arp 210 is an example of this.

A few others are radio galaxies -- these contain active galactic nuclei that produce powerful jets of gas called radio jets. The atlas includes the nearby M87, or Arp 152, as one of these radio galaxies.

Here is a photo of Arp #86 I took this evening. More commonly called NGC 7753, this is a spiral galaxy with a small nucleus and a small bar. NGC 7752 is a close companion that is apparently attached to one of NGC 7753's spiral arms. It was first thought to be an elliptical galaxy, but later images show that it is an irregular and disrupted system with three major H-{alpha} areas. The pair seem to have recently collided and are very similar to the M51 galaxy pair.

This pair is included in Arp’s catalog of unusual galaxies as ARP 86. The system is in Arp's class "spiral galaxies with large high surface brightness companions on arms".

I inverted the colors on the photo -- an old astronomer's trick that brings out some of the hard-to-see details. The smaller galaxy is more easily seen in the inverted image.

Observation notes:

2006 September 16, 22 hours 52 minutes local time.

Sky -- excellent. 4.5 out of 5. Dark sky. No moon.

5 minute exposure on 3 megapixel CCD.

14 inch Schmidt Cassegrain Telescope with 3910mm focal length.


Another Look at Comet Faye 4P

Here is another look at Comet Faye 4P.

This was taken with a 14 inch Schmidt Cassegrain with a focal length of 3910mm. The image was taken with a 5 minute exposure using a CCD with 3 megapixels.

As often happens with comets, the lesser power gathers more light from the tail. Here is a shot taken with a 85mm APO refractor with a 480 mm focal length.

The image is not as good and clear, but the tail shows up better.

Faye was discovered in 1844 and has a short 7.5 orbital period.

For my previous observation, go to:



3200 Phaethon

Comet: 3200 Phaethon
Date and Time: 2 September 2006
2302 UTC
Observing Location: Lawrenceville GA

Instrument: First photo used a 14 inch Schmidt-Cassegrain Telescope with 3910 focal length.

The second image used a 34 mm reflector with 135 mm focal length. Skies were excellent. It shows the comet with a highlighted circle.

I felt the tail was clearer in the lower powered telescope. The nucleus is bright. Tail is hazy, but it is clearly a tail that is on one side of the comet rather than a hazy surrounding a star-like object.