Continue reading... »

Herschel Prism
Today I re-assembled my 4-inch refractor. Last week, the tube was shortened by two inches to be able to (hopefully) enable the TAL 100RS with the Baader Herschel prism. Yesterday I sprayed the tube with white paint, and this morning I couldn't wait to test it with the new Baader Herschel prism. It snapped into focus without any problems. Maybe I just have to collimate the refractor a little, because the lens cell has been removed.

The views with the Herschel Prism (in combination with the Baader Continuum filter) are very sharp, and the Sun stands out against a jet-black sky. The granulation is visible at once, and looking at the big sunspot that is around right now, the contrast between umbra, penumbra and the sun's surface is stunning. Maybe I can shoot some images tomorrow. However, the sunspot is moving rapidly towards the limb of the Sun, so I just have to wait and see.

Wil Tirion
This afternoon I went to my local astronomy club, where Wil Tirion gave a really interesting lecture about the history of mapping the stars, and about his own work as a cartographer of the night sky. We also got the chance to have a look at many of his beautiful and accurate Sky atlases, star charts, and other publications. Of course I couldn't resist buying one of the newer publications he worked on, Collins' Atlas of the Nightsky by Storm Dunlop. The book is illustrated by Wil Tirion (star charts) and Antonin Rukl (moon maps), and covers the Moon, the Planets and the deepsky (northern and southern hemisphere).

I will be back soon with some more info on this book, but also on the Herschel prism.

Clear Skies!




Baader Herschel Prism

« Collapse

Continue reading... »

To warm up for a long night of observing I started with one of my favourite doubles, Eta Cassiopeiae, also known as Struve 60. The difference in colour and magnitude is just wonderful. The A component is a golden magnitude 3.4 star. At a position angle of 317º lies it's companion, a yellow-orange magnitude 7.5 star. The separation between both stars is about 12", an easy split even at lower magnifications.

After half an hour my eyes where adapted to the dark, and it was time to visit some open clusters in Cassiopeia, M 103 which a have observed a few times before, and a few "new" ones on my list, Trumpler 1, NGC 663 and NGC 654. As you can see on the map below, the four open clusters are all situated in the area between Delta and Epsilon Cassiopeiae. You can enlarge the map by clicking on the image.



Map from SkyTools 2 by CapellaSoft


M 103 (01h33.2m +60°42')
This small open cluster looks like a small triangle or Christmas tree. It is only 6' wide and its magnitude lies between 7 and 8. At a magnification of 133 I counted about 20 stars, at 200x about 30. What is clearly visible is that two of its brightest stars can be found at two of the apexes of the triangle. The star at the "top" of the Christmas tree is yellow white. The star at the southeast apex is bright white. Right at the centre of the cluster I detect a pair of stars that seem to be yellow and blue, but I'm not 100% sure about this one. Others report a 9th magnitude red star at the centre. I cannot find it but maybe my telescopes aperture is to small to detect colours of 9th magnitude stars.

Trumpler 1
Now this little gem really surprised me, and I immediately recognized it. I had seen it before, when looking for other objects in the area, but I failed to identify it. I had to use a little averted vision, but I definitely saw two rows of stars, running more or less parallel to each other in NW-SE direction. One row holds tree stars that are very easy to see from my backyard. Using a little averted vision, a fourth star comes into view, while the other row also shows itself with three stars. With averted vision at lest 10 other stars pop into view. Trumpler 1 has a diameter of 4.5' and its visual magnitude is 8.1. It is a detached, strongly concentrated cluster with a large range in brightness and poor richness in stars. Be sure to visit this little gem the next time your in the M 103 area!

NGC 663
My next stop was NGC 663. This 16' wide, magnitude 7.1 open cluster looks more or less elongated, with a beautiful double to the east of it's brightest star. At a magnification of 133x the cluster almost fills the field of view. The best view however as at 100x (20mm Vixen Lanthanum). I counted more than 30 stars, when using averted vision. It's brightest star shines at magnitude 8.4. This is the first time I observed NGC 663, but it won't be the last. I wasn't in the mood for sketching tonight so I will save that for the next time. The image below comes very close to what I saw through the eyepiece. Click on the image to enlarge. The limiting magnitude is 12, north is up and west is to the left.



Image from SkyTools 2 by CapellaSoft


NGC 654
About 0.75 degrees to the north-northwest of NGC 663 lies my last open cluster for tonight, NGC 654. This open cluster has a diameter of 5' and its visual magnitude is 6.5.
NGC 654 is a very delicate, small open cluster. It has a lot of stars that seem to be of an equal magnitude. At a magnification of 166x, the stars keep popping in and out of view, but when looking a bit longer using some averted vision I count 15 to 20 stars. At the south-south-eastern edge of the cluster lies a bright, magnitude 7 or 8 star. At 133x the cluster is at its best. It looks like somebody spilt some grains of salt over a black tablecloth. A wonderful view.

About 23.00 UT it was time for a coffee break, but first I wanted to give my two light-pollution filters a little test. After trying them on NGC 654, NGC 663 and Trumpler 1 the conclusion was very simple. The Baader Skyglow left the whole view intact, but didn't make the sky look any darker. The Lumicon deepsky filter definitely darkened the background but......... killed a lot of the faint stars in all three clusters, and coloured the brighter ones. Conclusion: visually these broadband filters are of no use for observing open clusters.


PART 2: DOUBLE STARS, MARS AND M77
At 0.30hrs UT I started with the second part of my observing night with a few double stars in Aries. If you look about 10º south of Triangulum you will see three stars in a more or less crooked row. These are Alpha, Beta and Gamma Arietis, the three brightest stars in the constellation of Aries. I included the map below to give you an idea where to find Aries. Note the position of M 45, the Pleiades. It might help you to locate the three bright stars. I selected four doubles for observing tonight: 1, Gamma, Lambda and Epsilon Arietis.



Map from SkyTools 2 by CapellaSoft


Gamma Arietis
I started with the brightest of the four doubles, Gamma Arietis. This is a magnitude 4.8 star, that I can see with my naked eyes from my backyard. With a small viewfinder it is easy to spot. What I immediately noticed that there seems to be no difference in colour or magnitude between the two components. Both shine in a white light and after verifying I found out that both stars are of exactly the same magnitude, 4.8. They are separated about 7.8" and the B component lies at a position angle of 0º. At 100x I really enjoyed these two celestial gems for a few minutes. Double stars are fun, even under light polluted skies!

1 Arietis
This is a close pair of stars, only 2.8" apart from each other. I could split them at 80x (hint) and 100x (sure), but the best view was at 166x. The brighter, magnitude 6.2 A component looks yellow while the magnitude 7.2 B component, lying at a position angle of 166º, looks white. 1 Arietis can be found 1.75º north-northwest of Beta Arietis. A very nice couple!

Lambda Arietis
To locate Lambda Arietis, just go northeast for a little more than 2º. Lambda is a very wide double, separated by 37.4". The A component is yellowish magnitude 4.9 star. The bluish magnitude 7.7 B component lies at a position angle of 46º. This double was at its best with the lowest possible magnification of 62x.

Epsilon Arietis
This double is a very though one. They are almost of equal magnitude (5.2 and 5.5) but only 1.5" apart from each other. Maybe the seeing had deteriorated in the last hour, because I was able to split 1 Arietis, which components lie 2.8" apart, but I was unable to split Epsilon, even at 400x. As you can see on the map above, Epsilon lies almost halfway between Aries and M45. I will have to wait for a more stable atmosphere before trying to split Epsilon Arietis.

Mars
Around 1.45 UT Mars was already high in the southeastern sky, together with the Pleiades. Because the seeing was getting worse I first didn't want to point the telescope at Mars, but on second thought I decided to give it a try. I was surprised! At 166x I definitely detected some darker areas on the rust coloured surface, and both poles looked white. Because Mars was jumping up and down due to the bad seeing, higher magnifications where not possible.

M 77
Around 2.15 UT (I was getting really tired) I decided to go for one last object, M 77 in Cetus. I had never seen it but tonight it was relatively high in the sky, and should be easy to spot. I could see the 4 or 5 stars that mark the tail of Cetus, so I had a go at it. As you can see on the image below, M 77 can be found 3 to 3.5 degrees south of Gamma Ceti, the second brightest star in the tail of Cetus. I didn't expect to see anything at lowest magnification, but I was in for a surprise again. I think that after M 31 this is the easiest galaxy for me to see. Using direct vision, it has a very bright core at 62x, even as bright as a star (9th magnitude) that lies to the east southeast of the galaxy. At 166x, using averted vision, the galaxy almost doubles in size, a round glowing disk with a very bright and large core. A great object to end my long night of observing at 2.40 UT. I can only come to the conclusion that even in a suburban area you can enjoy a long night of deepsky observing. You only have to choose the right objects!

Clear skies!



Map from SkyTools 2 by CapellaSoft
« Collapse

Continue reading... »

Sky-Watcher EQ-6
While deciding which new mount to buy, there where a few things that I took into consideration: I wanted a mount that could carry larger and/or heavier OTA's in the future, but still could be transported to a dark sky site. The mount would not be used for long exposure photography and finally, as always, there was the money issue: how much can you spend?

The search for the mount quickly narrowed down to the EQ-6. The Sky-Watcher EQ-6

- could take heavy loads (up to 22 kg) using a standard dovetail;
- should be OK for taking short exposure images of the Sun and Moon;
- could be equipped with several types of digital setting circles;
- could be transported to a dark sky site;
- fitted nicely into my budget;
- seemed to be good value for money.



EQ-6/Argo Navis on "wheels"
Click to enlarge


Argo Navis Digital Telescope Computer
Once I decided to go for the EQ-6 I started looking for digital setting circles (the EQ-6 wasn't available with a goto system in may 2004). There where several systems on the market, but there was one that really stood out from the others, the Argo-Navis Digital Telescope Computer from Wildcard Innovations. This computer can be connected to a wide variety of mounts, including dobs mounts, with encoders that are produced by JMI. The Argo Navis can be ordered, completely with encoders, from JMI in the US or from Wild Card Innovations in Australia. The specs of the Argo Navis computer blew away all other systems at that moment (may 2004). You can read all about the Argo Navis by following these links:

JMI NGC Super Max (Argo Navis)

Argo Navis Digital Telescope Computer by Wildcard Innovations

but here are the specs what made me decide for this unit:

- very easy to use out in the field, even when wearing gloves;
- a big rotary dial and two buttons do all the operations;
- the display comes with a dew heater;
- the display is dimmable with 100 settings and has a digitally contrast control;
- its database with more than 29.000 objects
- a wealth of bright stars, variable stars and doubles stars in the database;
- data on most objects: position, size, magnitude, surface brightness, class, star chart cross reference etc,
- the tour mode: let Argo Navis take you on a tour along your favourite objects;
- add 1.100 user-defined objects;
- can be used on many different equatorial mounts but also on dobsonian mounts;





Click to enlarge

So the combination I went for is the Sky-Watcher EQ-6 and the Argo Navis Digital Telescope Computer. As you will read in the next paragraphs, I don't regret it.

Setting up and using the EQ-6
I have been using the Sky-Watcher EQ-6 mount for more than a year, and I'm very satisfied. The setup is done within minutes. You just have to assemble three parts: tripod, mount and counterweights, connect the battery and the hand-controller, and you're ready to go. The mount itself is the heaviest part, weighing 16 kilograms, but it can definitely be carried around and transported in a small car. Taking the EQ-6 apart also takes only a few minutes.

After assembling the Sky-Watcher EQ-6 I usually align the mount with the celestial pole, using the built-in Polar Scope. This only takes about five minutes. Once the EQ 6 is polar aligned, it keeps all stars and deepsky objects right in the centre of the field of view. I have been indoors once for more than two hours, leaving my telescope centred on M 37. When I returned, M 37 was still visible right in the middle of the eyepiece. When using digital setting circles, it also pays of to align exactly on the pole (see next paragraph). The EQ-6 has no different speeds for stars, moon and sun, but I never experienced any problems with that. The Sun and Moon are kept in the eyepiece nicely. Every now and again you need to perform minor adjustments.

I mounted different telescopes on the EQ6, my 8-inch TAL 200-K Klevtzov-Cassegrain (12 KG), the TAL 100RS 4-inch refractor (6 KG) and the 40mm Coronado PST (2-3KG). I also mounted the TAL 100RS and the Coronado PST together using a Duo-Mount bracket from Teleskop-service in Germany. The mount proved to be very stable on all occasions and changing telescopes was very easy using the standard EQ-6 dovetails.




Click to enlarge
In the period I've been using the EQ-6, it always worked correctly. The hand-controller though looks a bit cheap and has a bright green LED in the middle. A little sturdier box and control buttons, and a red LED would be great improvements for the future, but then again everything worked just fine until now. I also have used the EQ-6 for short-exposure photography with the Coolpix 4500 connected to the eyepiece (Scopetronix / Vixen adaptors). The images of the Moon and Sun I got were just perfect. I am not interested in deep sky photography, so I can't tell you what the EQ-6 is like, when using it for long-exposure imaging.

After using the EQ-6 for more than I year I can say that I'm very satisfied with this mount. I paid 999 Euros but it is worth every penny, a fantastic mount for a very down-to-earth price. What other mount can carry 22 KG in this price range? I couldn't find it, so the choice was very simple, and I do not regret it for a moment! This is definitely value for money.

Setting up and using the Argo Navis Digital Telescope Computer
I ordered the Argo Navis and a set of encoders (8192 steps) for the EQ 6 from JMI. The package arrived in good order, and the installation of the encoders took me about 15 minutes. The only piece of equipment I used was a screwdriver (on the images below you see the RA and DEC encoders mounted on the EQ6). After the installation of the encoders I installed 4 AA 1.5V batteries to provide the internal power for the computer (at the moment I use an external DC power cable to connect the Argo Navis to 12V power pack). Finally, I connected the computer to the encoders using the encoder cables. After printing out the manual, I was ready to do the initial setup.



Click to enlarge
After going through the initial setup (which you only have to do once and takes about half an hour) I started the alignment procedure. This procedure has to be done every time you setup your telescope. The alignment procedure is very simple for the EQ6. Connect the Argo Navis to the encoders (and to the external power source). Be sure that the telescope is polar-aligned exactly. Power up the Argo Navis and align the telescope on a star that you select from the alignment star list and you are ready to go.

You can also use the "rough align" mode, but you have to align on two stars. I have not used this mode, because I always had Polaris available to align the EQ-6 mount. However, when you cannot see Polaris from your observing site, you can use the rough-align mode from the Argo Navis. What I've heard from other users, this works fine.

After using the Argo Navis for more than a year I can only say that I am impressed with this great piece of equipment. If the mount is exactly aligned to the pole, you can align the Argo Navis within one or two minutes, and from there it will take along any number of objects. One night I just tested the Argo Navis for locating different targets. I let the computer take me to 40 different targets: double stars, open clusters, planetary nebula's, planets and globular clusters. They all ended up in my 45' field of view the first time. The Argo Navis did not miss one! And then the wealth of details you get on all the objects is fantastic. Here's an example (M 31):

M31, also known as NGC 224, Galaxy in Andromeda, _size=3.18 degrees x 1.03 degrees, mag=3.3, SB = 14.5 _morph=SA(s)b, Andromeda Galaxy M31, very bright, _RA= 00:43:00, DEC = +41deg 17’35” above horizon, _SA=4

(The last data “SA=4” means that you find M31 in the SkyAtlas 2000 on map 4. You can change this into the Millennium Star Atlas or the Uranometria edition 1 chart numbers)

Another great feature of the Argo Navis is the Tour mode. One night, when I came home from work the sky was covered in clouds, but later that night suddenly the clouds disappeared, so I could observe for an hour or two. I had nothing like an observing list or program ready, but the Argo Navis has a "Tour Mode". In this mode I simply chose a constellation and objects I would like to see, and let the computer do the rest. I let him take me along all different kind of objects within Orion, brighter than the 10th magnitude. I had a great time and I really felt like an astronomical tourist. Clusters, asterisms, double stars, nebulae, they all came along. This option is fun!

In the end I can say that the Argo Navis amazes me every time I use it. This unit proves not only to be very reliable and accurate, it also is very easy to use. The whole unit is controlled with two buttons and a big rotary dial, very basic and simple. You don't have to take of your gloves to use the controls. I never had any dew problems or technical failure due to outdoor conditions. Uploading a list with user data is a piece of cake with the software that accompanies the Argo Navis. The wealth of detail that is displayed on the adjustable two-line LCD screen is just another great bonus you get from the Argo Navis. The tour-mode is wonderful, and the manual that is supplied on a CD-rom is very accurate and detailed.

Conclusion:
If it comes to navigating the night sky, the Sky-Watcher EQ-6 and the Argo Navis Digital Telescope Computer form a great team. If you have any questions or remarks, please feel free to post a comment.

Clear skies to all of you!
« Collapse

Continue reading... »

This sketch should give you a general idea where the different features where situated on the solar disk.

1. Three large QRF’s (Quiet Region Filaments)
2. Active region 791 with a sunspot and two plage’s (white areas around Sunspot)
3. Active region 792 appearing at the limb of the Sun with bright plage
4. Big prominence, probably an active Class II eruptive (from Zirin classification)
5. Large hook shaped prominence.

The first two images where shot with a 10mm eyepiece and 2x optical zoom, 1/4s, f 10.3, ISO 100. The first image is the original image, slightly altered with some level adjustment and unsharp masking. Two filaments and the big prominence (4 on the sketch) are visible as well as the brighter area of Active Region 792 on the limb of the Sun (about 1 o’ clock). The second image shows only the green channel from the first image. The prominence disappears but the surface features are much better visible.

The next image shows a large part of the Sun, again only in the green channel. The original image was shot with a 12mm eyepiece, no optical zoom, 1/30s, f 6.6, ISO 100. Again some unsharp masking and level adjustments have been applied. On this image you can see the three filaments and at the bottom centre active region 791, a sunspot with some bright plage’s above and to the right.

The last image shows the big prominence. This image is an RGB one, but I split the colour channels, did some level adjusting, unsharp masking and curves adjustment only in the red channel, before merging the three channels together again. This produced a more or less realistic image of the big prominence, but a lot of testing and training has to be done. However, this being the first images shot through the Coronado PST, I am very satisfied. If you want to comment on the images or have some more tips for me, please feel free to do so! You just have to register once and you can always log into the comment fields.

Clear skies to all of you!

UPDATE friday 29 July 2005 at 14.00 hrs UT !!!!!

At the moment there is a big prominence visible as well as the active region AR 792. Here are some images from some two hours ago (click to enlarge!)

Enjoy the images for now. Details on the images will follow within the next few days. I will keep you updated.

« Collapse

Continue reading... »

My all time favourite double star is Beta Cygni, better known as Albireo. I have been observing Albireo for more than
25 years using a wide variety of telescopes and binoculars. For me personally this wonderful double hasn't lost much of its charm. I find Albireo at its best through my 4-inch refractor at a low magnification (30x): a superb golden-blue pair of stars against a more or less black background, a true celestial gem.

The name Albireo, seems to be the result of a mis-translation of the term Ab Ireo from the 1515 edition of Ptolemy's Almagest (star catalogue). According to R.H. Allen (Star Names, their lore and meaning) the original Arabian name of Albireo was Al Minar al Dajajah, the hen's beak. Deneb, marking the tail of the Swan, comes from Al Dhanab al Dajajah, the hen's tail. Gamma Cygni or Sadr, right at the heart of the Swan comes from Al Sadr al Dajajah, meaning the hen's breast.

Albireo is very easy to locate (see map below). First look for the constellation Cygnus, the Swan. In light-polluted suburban areas you will be able to identify the Swan as a large cross in the sky, with the bright white Deneb (Alpha Cygni) at the tail of the Swan and Albireo (Beta Cygni) at the swan's head.

Albireo consists of 2 components, a bright magnitude 3.1 orange class K giant star (like Arcturus) which is fusing helium into carbon and a magnitude 5.1 blue-white class B-dwarf that transforms hydrogen into helium (like our own Sun). The brighter A component has a luminosity of more than 700 Suns, while the dimmer B component is a 100 times the (visual) solar luminosity. The stars are separated by 34". The position angle of the B component is 54°. Albireo is probably a true physical double star, although hard evidence of orbital motion has not yet been detected. Recent measurements place them at a distance of almost 400 light years. According to these same measurements, the distance between the two stars is about 9 light years. However, the uncertainty of the distance of each of the components is about 25 light years.

So go out and observe Albireo! For me personally, nothing beats the "live" view of a beautiful double star. There is no sketch or image that comes even near to what you see through the eyepiece.

Clear Skies!


Click to enlarge (Image from Skytools 2 by CapellaSoft)
« Collapse