Friday, December 20, 2013

Arduino ASCOM focuser kit

Maybe you remember the ASCOM jolo focuser project - now it has the production implementation! Some of my astro colleagues took a chance and we made an action. 15 circuit boards has been ordered and 10 ready to use kits have been made. 5 other users ordered just clean boards to make the kit by theirselves. You can see how the device look like:

The reference solution uses L298 stepper driver and works with half steps by default. You can find all the documentation, schematics, source code and PCB project at . 
There were some problems with first revision of PCB thats why you can see a few wires around the Arduino board :) 

Clear skies!

Wednesday, December 4, 2013

Coin throw contest part I - galaxies

One may wonder how large are the objects presented in the blog. Actually they are huge - hard to imagine their actual size, but many people are also interested in their apparent size in the sky. Well, the scale can be quite different. It is quite nice to compare this to some objects we can imagine to place at some distance and see. Let us start with big ones.
Every one knows what is apparent Moon size - when it shines bright in the night sky, seems to be pretty large, but there are many objects in the sky that have larger apparent size than Moon. Apparent Moon diameter is about half degree, so 30 arc minutes. Do you think you can cover the Moon holding 1 cent coin in the hand? Actually yes, and with ease. 1 cent coin has diameter 16mm and you should put it about 170cm away from your eyes to make it apparently as large as Moon (30 arc minutes of diameter). Quite a lot of nebulaes and some galaxies have apparent size larger that Moon. Andromeda galaxy is the largest one that can bee seen in the northern sky - it's apparent diameter is 3 degrees, so it is 6 times larger than Moon! Problem is it is very, very faint, can be seen with naked eye under dark sky as just a little haze. But if you would be able to see M31 galaxy as it is presented in the photos it would be as large as 1 cent coin seen from 15cm distance!

Near M31 galaxy there is another one - M33 in the Triangulum constelation. This one is a little bit further and also is a smaller galaxy. Apparent diameter of the M33 is about 1 degree, so about two times as apparent Moon diameter. However the outer arms of M33 are very faint and can be seen only in long exposured photos, like the one below:

But still, if we would be able to see M33 galaxy million times more luminous than it is the view would be magnificent! Using the same 1 cent coin you need to move it about 85cm away to make it look as large as M33 is in the sky.
There are a dozen or a little bit more galaxies with apparent size comparable with Moon diameter, and then we go deeper into the galaxies that are more distant. An example can be NGC4725 galaxy in the next picture. This one has apparent size of 1 cent coin placed about 5 meters away. So not an easy catch and not too many details could be seen there:

NGC4725 galaxy can be vieved using 6" diameter telescope under dark sky, but do not expect to see more than just a little fuzzy blob in the sky. This galaxy is about 20 times more distant than described above M33 and M31.
There are of course much more galaxies - the deeper we look the more there are. Next picture shows Abell 347 galaxy cluster. It is about 200 million light years away, so the galaxies seem to be pretty small, but actually they are just quite distant. Using 12" diameter telescope under dark sky you will be able to see a few of them as just little fuzzies in the dark background. The whole frame is about of the half of apparent Moon diameter, and the nice spiral galaxy at the upper right part has the apparent size of 1 cent coin viewed from 30 meters. 

So still not so small, and can imagine this size, right? Well, lets do another step (in the apparent size, not actual distance) and take a look into high resolution picture of the Moon:

The tiny crater at the picture has diameter of 4km. But the magnification of this picture is quite large, and if you would like to use again our 1 cent coin to cover this crater we need to move the coin about 1.5km away. Such high resolution image can be done with bright objects (as planets or Moon) using different technique than for deep sky objects - in this case we use short exposures, then choose the best frames and stack them to get detailed picture. This way we can in some extent get rid of atmospheric turbulences effect that ruins resolution when observing from the Earth surface. Hubble Space Telescope has not this problem at all :)

At the end - kind of mosaic to present all this article pictures in one place. All pictures has been taken using moderate 6" diameter newtonian telescope but using different cameras and techniques. When I started to be interested in astronomy (about 20 years ago) I would never imagine to obtain such results using so small telescope from the backyard. Things changed... :)

Clear skies!

Sunday, November 10, 2013

Island universe*

NGC891 galaxy looks as we think Milky Way would look like when viewed edge-on. In fact both galaxies are considered very similar in terms of luminosity and size. The galaxy is in the constellation Andromeda and was discovered by Caroline Herschel in 1784. It is a part of NGC1023 galaxy group and also a part of Local Supercluster. Galaxy is about 27 million light years away and its apparent magnitude is 10.8, so it can be just spotted in 4 inch telescope as a light smudge. To see dust line across galaxy one needs much larger instrument, at least 12-14 inches aperture. High resolution images of this galaxy show unusual filamentary patterns in the dusty disk (barely visible in my image). Scientists presume that supernova explosions can cause the dust to be thrown out of the galactic disk to the halo.

NGC891 is not the only galaxy in this picture - there are dozens of them. In the lower left part there is Abell 347 galaxy cluster. The cluster is about 200 million light years away and seven of them are brighter than 14 mag, so they are available for visual observers that have 10" or larger scope. The Abell 347 galaxy cluster is a part of one of the largest structures in the universe - the Perseus-Pisces Supercluster

Once again comparison between my work and image from Hubble Space Telescope:
Impressive, isn't it? And the HST image is actually scaled down to 50% of original resolution.

And the full frame:
Clear skies!

* "Island universe" is a term for galaxy proposed by Edwin Hubble in year 1924 when he discovered that some of observed nebulaes are actually other galaxies like the Milky Way and contains billions of stars. 90 years ago all galaxies were known as our Milky Way nebulaes, and since that time universe grown millions times. 

Thursday, November 7, 2013

Triangulum treasures

In the constellation Triangulum not much fancy objects there are... One spectacular is the M33 spiral galaxy - also calle Triangulum Galaxy, not because of its shape, but because of its position in Triangulum constellation. M33 galaxy (also catalogued as NGC598) is the third largest member of our Local Galaxy group. Contains about 40 billion stars (our Milky Way contains 10 times more) and its mass is estimated for 50 billion Solar masses. M33 apparent size in the sky is quite large - over two times more than apparent Moon diameter, but its surface brightness is very low. However under exceptionally dark sky M33 galaxy can be spotted with naked eye. Latest estimations indicates that Triangulum Galaxy is placed about 2.7 million light years away and it makes it probably the most distant object that can be seen with unaided eye. Between M33 galaxy and M31 Andromeda Galaxy there are several streams of neutral hydrogen and separate stars (see ) . It may indicate some past interaction that took place bewtween 2 and 8 billion years ago.

M33 galaxy contains many H II regions. Four of them have been discovered by William Herschel in 1784, and they are also listed in the picture below as NGC objects. The most famous of these regions is NGC604. This region is somehow similar in structure to Orion Nebula, but it is about 50 times larger. In fact, the NGC604 region would fill the whole distance between us and Orion Nebula that is placed about 1400 light years away.
In the picture below you will find marked some interesting objects placed in M33 galaxy. C27 and C39 are the largest globular clusters in this galaxy, and GR290 is LBV star that shows 1 magnitude amplitude eruptions every about 20 years, and smaller ones with scale of about 320 days. Other object are H II regions.

Another picture shows enlarged fragment of the whole frame. You can see here some faint and distant galaxies - about dozen of them. They are very remote, no exact data about actual distance, but basing on their size and brightness they may be a few hundreds or even one thousand times more distant than M33 galaxy. 

Clear skies!

Ah, the full frame of course - north is up:

And one more picture - NGC604 cut from my picture compared with Hubble Space Telescope image - guess which one is mine :)

Thursday, October 31, 2013

Quick Orion test

Just to present quick five minutes test picture of Orion Nebula M42. It is one of the brightest nebulae in the sky and is placed about 1340 light years away. It is also the closest to Earth region of active star formation. 
Picture below is single 5 minutes photo through hydrogen alpha filter.

Clear skies!

Tuesday, October 29, 2013

Bubble hydrogen attack

Not so long time ago I shot Bubble Nebula with modded Canon 450D. Total exposure was 6.5h and I was pretty happy with the outcome. But the time has come for narrowband exposures. Hydrogen alpha is the first filter used and this black and white result I present today. As you probably remember this filter passes the light that corresponds to the hydrogen presence in the space, so all cloudies in the picture are actually massive hydrogen regions. At the upper right border you can see fragment of M52 open star cluster (about 5000 light years away).

Bubble nebula (NGC7635) is actually hydrogen II region emission nebula placed about 11,000 light years away. The bubble shape is created by stellar wind from massive blue central star. 

In the right part of the picture you will find NGC7538 nebula which is the region of active star formation. This one is placed a little bit closer - about 9100 light years away from us. 

There is actually very little of dark sky in this area - the hydrogen is almost everywhere. That's why the whole picture is filled with some haze.
The picture itself has been shot with my current setup - GSO 6" F4.5 newtonian with Atik383L+ camera and Baader hydrogen alpha filter. Total exposure time was 5.5h. Next in the queue are Oiii and Sii images of this region, so finally I am going to greate HST palette image of Bubble nebula.

Clear skies!

Sunday, October 27, 2013

Morning comet triplet

There are always at least few comets visible in the sky. Usually there is one large enough comet to be visible in binoculars and others tha can bee seen with telescope. Once every few years there can be comet visible with naked eye. 
At the moment we have also a little bit unusual  scenario - in the morning sky in northern hemisphere we can see three comets with binoculars! These are comets: C/2012 S1 (ISON), 2P/Encke and C/2013 R1 (Lovejoy). Last night (actually today morning) I spent some time on imaging all of them.

2P/Encke has the shortest period of any known comet - it completes the orbit every 3.3 year. Its nucleus diameter is 4.8km. Encke comet orbit is unstable and evolves over time due to perturbations and outgassing. The picture has been shot at 04:27 CET and the exposure time was 5x60 seconds. The comet in this moment was about 80mln km from Earth and its velocity was 46km/s. At this distance the pixrel scale is about 950km/px (when enlarged).

C/2013 R1 Lovejoy is quite new comet discovered on September, 9th. This comet will pass its perihelion on December, 25th. The picture below was shot at 3:55 CET and exposure time was 5x90 seconds. The Lovejoy comet was 110mln km away at this moment and traveled across Solar System with velocity 38km/s. Piksel scale is about 1300km/px (when enlarged).

C/2012 S1 ISON comet is probably the most famous comet this year. It was discovered on Septermber 21st, 2012. The comet will pass its perihelion on November 28th, 2013 in a distance only 1.9mln km from the Sun center that is only about 1.2mln km over the Sun surface! At the end of this year the comet may become visible with naked eye under the dark sky. Currently its magnitude is about 9mag, so it is binocular target. The picture belowe has been shot at 4:11 CET with total exposure time 10x120 seconds. The comet was at this time about 200mln km away from Earth, so the picture pixel scale is about 2400km/px when enlarged.
One may wonder what the heck are these lines at photos? These are star trails - during the exposition time the comets moved significantly across the sky. So we could track the stars and have comet blurred or we could track the comet and have star trails. In this case the answer was simple :)

Clear skies!

Wednesday, October 16, 2013

Autumn tulips

Sharpless Sh2-101 or Cygnus Star Cloud are the alternative names for the nebula presented here today. Although it is much better known under the name Tulip Nebula. It is classic emission nebula that shines (faintly) in deep red hydrogen hue. The Tulip itself can be seen in the right part of the picture. This hydrogen cloud lies about 6000 light years away and its apparent size is 16'x9' so about half apparent size of the Moon.
The picture below is enlarged part of the Tulip itself. The exposure has not been long enough to record some more details, probably I will get back to this nebula some day.
And the last one is color HaRGB version with some star hue added to the stack.
You can see for comparison the same nebula shot with modded Canon 20D about one year ago.

Clear skies!


Some people ask me to create a one place when one can view all the images I present in the blog. I found it actually to be a good idea and reviewed a few solutions, also some well known galleries like flicker or picasa. But eventually created ultra simple page by myself. My idea was to make it

  • all in one place
  • readable 
  • easy to navigate
  • not processing uploaded images (like blogspot or picasa do)
  • able to show image in full size
  • present a short description with link to the blog entry
And thats all. The gallery is available at web address. 

Have fun!

Monday, October 14, 2013

Bloody sky

Not so long time ago I presented Crescent Nebula in hydrogen alpha emission line. The picture was black and white, but in fact the color that corresponds to hydrogen alpha line (656nm) is deep red. So this time I have made a few more exposures in RGB colors to catch some star hue and mixed it with hydrogen alpha signal using HaRGB technique. The result is as follows:

The Crescent Nebula (NGC6888) is placed about 4000 light years away and is formed by stellar wind from Wolf-Rayet star colliding with slower moving wind ejected by the star.

Clear skies!

Friday, October 11, 2013

Dust and blue

There is another piece of beautiful nebulosity in the Cepheus constellation - it is Iris nebula (NGC7023 or Caldwell 4). It is typical reflection nebula lit by the 7 magnitudo star SAO 19158 placed in its center. Actually the NGC7023 symbol does not denominate the nebula itself, but the star cluster placed immediately to the west of the nebulosity region. The correct designation of the nebula is LBN487. Dust particles that shines in the Iris nebula are leftovers from when the star was formed. 
The whole complex is about 1300 light years away and its radius is about 3 light years. There are also faint hints of red color surrounding the central star - this is evidence that some hydrogen emission takes place.
The photo above has been exposed during three nights - 10h total exposure of luminance and 5h total RGB channels. Processing took me more less the same amount of time - I started all over again four times from scratch. Iris nebula is quite demanding target and requires dark sky (not at my site), fast optics (I am almost there) and large aperture (not really me :) )
Below cropped nebulosity center:
Clear skies!

Thursday, October 10, 2013

NGC7822 star nursery

There are many hidden astrophoto treasures in the constellation of Cepheus (although not so many for visual observations). One of them is nebulosity called NGC7822. It is a young star forming complex. The complex is about 3000 light years away, and younger components are believed to be 'only' few million years old. The complex also contains the hottest star within the distance 3000 light years from Sun. It is  BD+66 1673 star - an eclipsing binary that one member is about 100 000 times more luminous than Sun and its surface temperature is about 45 000 K.
The picture above is a resized full frame stack of 10 minutes subexposures made with Hα filter, so only the light emitted by excited hydrogen atoms have been recorded. You can notice many of so called pillars of creation where stars are formed.
Below is the enlarged part of the picture.

Clear skies!

HEQ5 on steroids

HEQ5 equatorial mount is not top quality. It is build in China, often requires some adjustments when you receive it. But on the other hand the price is very acceptable, and you can start your astronomy adventure with not really astronomical investments. 
Due to its flaws many amateurs wanted to improve HEQ5 - mainly for astrophotography purposes. There are two popular modifications made for HEQ5 mount:

  1. replacing original Chinese bearings with some better ones made by more reputable companies (EZO, Timken, FAG)
  2. replacing original gears with belts and pulleys
The first modification I already made some time ago. Now the time has come for second one :) There are two types of belt mod kits - one changes original gear ratio so it can be controller only using laptop and EQMOD interface. Another type keeps the original ratio, so there is no limitations to future use of the mount. These second type requires some fancy small 9 tooth pulley and usually are a little bit more expensive. Me and few other astro amateurs have chosen belt mod kit manufactured in Rowan Astronomy company located in UK. This one keeps the original 9:47 gear ratio so it is transparent to any controller.
The kit has come well wrapped. It contains four pulleys, two belts, acrylic cover spacer, two steel pins for idlers and two idler rollers, three different allen keys and 6 head screws for cover. Additionally one can order pinion extractor to remove the pinion gear - I can recommend this tool. This gear sits tight on the motor shaft and is not so easy to remove.
There is also very detailed instruction provided for the whole process. It took me about one hour to replace the original gears with the belt kit mod. Un-twisting motor wires can take some significant amount of time.
Above there is declination motor with plate and two gears. The larger one will be replaced with idler roller. The good news is that there is no need to move the main worm gears, so you do not need to adjust it again. This worm gear adjustment process can be time consuming.
Stepper motor with pinion gear removed. The extractor did its job perfectly :)
New 9 tooth pulley on place and idler roller fixed to the plate.
Declination belt mod on place. Now the right ascension part to go.
Voila! All kit elements fit precisely and there is no more annoying noise during mount moves. Unfortunately weather forecast says that I will need to wait few days for real test :( 
There are few advantages when using belt mods:
  1. quiet mount work :)
  2. smoother guiding (especially important for the astrophotography with longer focal lengths like over 400mm)
  3. more regular periodic error correction (PEC) so it can be recorded now and can work better when making unguided photos
Some real life tests to come...
Clear skies!

Friday, October 4, 2013

Andromeda by the way

Andromeda Galaxy (aka M31 or NGC224) is a spiral galaxy approximately 2.5 million light years away from Earth. It is the nearest spiral galaxy to our Milky Way, although there are some other galaxies closer to us, but not spiral (like Magellanic Clouds). As one can easy guess the galaxy can be seen in Andromeda constellation. SST observations revealed that M31 contains over one trillion stars (1012) - this is the largest galaxy in our Local Group. Andromeda Galaxy is moving towards us and in about 4.5 billion years both galaxies will collide and eventually merge into large elliptical galaxy.
The galaxy itself can be viewed with naked eye. Its apparent magnitude is about 3.5, but it covers quite a large area in the sky. The galaxy core is quite compact - core apparent diameter is the same as the Moon apparent diameter. But the external arms are spread 3 degrees wide, so it is 6 times more than Moon diameter. However only the core is visible with naked eye, to view the arms you will need good bino or telescope. 

Picture above is only one 10 minutes exposure I made last night. The galaxy has not been my target, but I needed to rotate telescope through the whole sky and decided to spend few minutes in this place. In the picture bottom there is M110 galaxy, and above M31 there is NGC206 star cloud. NGC206 is the richest and largest star formation region in our Local Group of galaxies.  Below you will find the crop of the galaxy center.

Clear skies!

Thursday, October 3, 2013

Incandescent Crescent

Crescent Moon is an easy target for any stargazer. However not many know that we have another crescent in the sky. This one is well hidden in constellation Cygnus and cannot be viewed with naked eye - the Crescent Nebula (NGC6888) shines faintly somewhere there and can be spotted with medium sized telescopes using filters. Nebula is placed about 4000 light years away and is formed by stellar wind from Wolf-Rayet star colliding with slower moving wind ejected by the star when it become a red giant star a few hundreds of thousands years ago. The result of this collision is a sheel and two shock waves. The red giant center star will some day (in about one million years) explode as supernova, and then whole this space region will be changed.
Picture at the top is enlarged crop of the full frame (below). It has been shot through Hα Baader filter with total exposure time of 3 hours and single exposition of 10 minutes.
Clear skies!

Tuesday, September 17, 2013

Atik power hunger

Atik 383L+ is for sure great bang for the buck camera - large KAF8300 sensor with over 8 million pixels, quite sensitive (about 55% peak QE and 45% for hydrogen alpha line) and no problems with software and hardware. Almost no problems...
One can find some reports in the Internet about excessive noise and hot pixels present in the raw frames taken with 383. Common factor for this phenomenon was low supply voltage. When the camera is supplied with voltage lower than rated the noise and hot pixels amount rises. When voltage drops to 11.5V or below the amount of noise becomes overwhelming. It may have effect only on cameras manufactured before year 2012. And I discovered it also affected my setup - in the picture below you can see fragment of the 15 minutes hydrogen alpha nebulosity region near by NGC6914 (the right part). The overall picture is just a noise :(

So far I was very happy with my 12V 5A power supply that feeds the whole setup. After taking the dark frames library with camera connected directly to power supply I also had not noticed any alarming noise. However after the camera first light I found out some more than unpleasant amount of hot pixels in the frames. I investigated Internet a little bit on it and decided to make some measurements. My 12V power supply gives voltage 11.9V that drops to 11.8V under full load. That's perfectly OK, because it means keeping rated voltage within 1.5% range - almost perfect. Not for Atik :) When taking darks the voltage applied directly to camera was 11.8V so the calibrations frames were in a good shape. However when camera has been attached to the setup the two additional connectors and about two meters of cable stood in the way. These obstacles gave another 0.5V voltage drop, so the effective voltage at camera was 11.3V - it was way too little and the hot pixels came out like mushrooms after the rain (like in the picture above). 

The supply voltage needed to be increased. There were several ways to do it - for camera alone, or the whole setup, with new regulated power supply, or some converter. I purchased a DC/DC step up converter to do some tests and to use it in the field. Now I am also able to connect it to the battery or akku and  have regulated 13.5V in the field to power up my set up. 

For the backyard astrophoto I use old but hale regulated power supplier 13.8V / 10A with decent transformer inside. It weights somewhere around 3kg and can be used for self defence as well :) It also heats like a little oven, but is extremely stable and simple to use and maintain. Under the full load (about 4A top) the output voltage from this supplier drops by about 0.02V. 

Only synthetic results so far, but promising :) My last calibration frames I took at 11.8V and the new ones has been exposed at 13.5V. The direct comparison is below:

Top row contains stacked master dark, bottom row single 10 minutes dark frames. Left pictures are at 11.8V, right ones at 13.5V. Even here the difference is obvious, and the pictures at 11.3V contains dozen times more hot pixels (see first picture in this blog entry).
Now I impatiently wait for clear skies...

As usual...
Even under the clear sky I already wait for another one... :)

Clear skies!

Saturday, September 14, 2013

To catch a cosmic ray

Cosmic rays are very high energy particles that penetrate Earth atmosphere and sometimes even reach the surface. High energy means much, much higher than for example we are able to generate in the Large Hadron Collider. Most energetic cosmic rays particles observerd had energy 40 million times larger than particles accelerated in the LHC. These particles are mainly originated outside the Solar System and even outside the Milky Way. Every few moments at least one of this particles goes through your body. They have sufficient energy to alter the state of electronics integrated circuits causing errors to occur such as corrupted data in memory or incorrect performance of CPU.
They also affect day by day astronomers work of course causing different artifacts on long exposured CCD sensors. Here is the dark calibration frame taken with Atik 383L with exposition time of 20 minutes. The sensor has not been actually exposed to any light - it was tightly covered with the metal cap. You can see (when enlarge) there some hot pixels and some thermal noise (sensor has been cooled to -20C). And also during these 20 minutes some cosmic rays hit the sensor surface at different angles and caused some artifacts.

In the next picture some of this artifacts have been cut out and enlarged. You can see how different they are. You can also try to imagine what happened during this exposition, when those cosmic wanderers eventually hit the sensor surface after the million years of traveling across the space...

The origin of cosmic rays is still a little bit mysteriuos. It is believed that some of them are created during supernovae and other big stars explosions, but active galactic nuclei probably also produce cosmic rays.

Clear skies! (even under cloudy sky cosmic ray can hit you :) )