Archive for shift-and-add

Moons of Saturn through telescope

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , , , , on 2011/03/09 by computerphysicslab

Titan, Tethys, Rhea, Dione, Iapetus are five bright moons of Saturn, the ring planet in our Solar system. They can be observed through amateur telescopes with at least 100mm (4 inches) of aperture. The following picture was taken through a 5 inch telescope, a Celestron NexStar 5 SE XLT. It is an image composed of 84 single subframes of 1 second of exposition each one.

It was taken on 2011-03-06 02h10mUT using a DBK 21AU04.AS Imaging Source CCD camera. Planet was recorded in a different exposition through a video stacked (shift and add) using Registax free software.

Check out the JPL simulation matching the picture above.

Auriga and Moonlight

Posted in Astrophotography with tags , , , , , , , , on 2009/10/10 by computerphysicslab

This is a set of 71 single shots of 10 seconds each one to the Auriga constellation on 2009-10-08. The Moon was located at its south and its brightness is visible on the edge of the image and on the background gradient. The single frames were recorded using a Canon Rebel XTi (EOS 450d) and a conventional EF 18mm lens. The Kids is a triangle of stars on the upper side of Auriga constellation.

Auriga-Moon-18mm-71x10sec-Wordpress

Manual Crazy Tracking

Posted in Astrophotography with tags , , , , , , , , , on 2009/09/01 by computerphysicslab

Lacking of an equatorial mount I have built myself a kind of manual tracking system that keeps into the field of view of a webcam a planet like Jupiter, for 3 minutes. This is long enough to record useful data and then post-process it with aggressive wavelets.

The resulting tracking is not at all perfect. You may see Jupiter swinging around the screen. It is important to capture the data at a fast shutter speed (1/100 sec.) to avoid motion blur in every frame because the planet is always dancing.

In spite of this movement, the results after stacking are very good. Here I show this really simple system and the resulting yesterday’s Jupiter with the webcam:

Manual-Crazy-Tracking-01

Manual-Crazy-Tracking-02

Manual-Crazy-Tracking-03

As you can see the Manual-Crazy-Tracking is a very simple system that consists in a rubber band attached to the tripod handle. If you try to track manually directly pushing the tripod handle, the shaking is excessive and you would need a very very fast shutter speed to get some useful data. The rubber band is necessary to reduce vibrations and increase the shift movement control.

At beginning Jupiter is located in the center of the field of view with no need to any corrections. As long as it drifts due to its sidereal movement you will have to pull using the rubber band in order to keep it in the center of the screen (it is supposed you have a laptop there capturing and showing images from the webcam). This way you may have Jupiter centered in the screen for a long time. You will have time to focus (left hand pulling the rubber band and right hand tweaking the focuser) and time to expose.

Jupiter, Io & Wesley impact scar

Posted in Astrophotography with tags , , , , , , , , , , , , , on 2009/08/28 by computerphysicslab

Good seeing yesterday too (2009-08-27 23h05m UT). Wesley impact scar is fading day after day, but it is still there. I made an animation that shows Io approaching Jupiter’s limb: http://www.youtube.com/watch?v=78zJtv569y4

Jupiter-Io-Wesley-impact-2009-08-27-23h05m-UT

Big Jupo

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , , on 2009/08/27 by computerphysicslab

I have a good seeing last night. So I got my best Jupiter yet. Here it is:

Jupiter 2009-08-26 Sharp

It is 4x resampled via Registax Mitchell and PS. After resampled I can spot more details in bands and polar zones.

As always I used the 6-inch no-EQ mounted newtonian reflector, the 14mm eyepiece doing afocal projection over the Canon EOS 450d (Rebel XTi) body and recording video using “EOS Camera Movie Record” free software. Three times Jupiter crossed over the field of view. Registax and VirtualDub added and stacked the footage properly.

M42 with point & shoot digicam

Posted in Astrophotography with tags , , , , , , , , , , on 2009/08/26 by computerphysicslab

It is interesting to explore the possibilities of some common devices such as digicams and binoculars. I have been reprocessing some old stuff from March. I took 474 single exposures of M42 in Orion through the binoculars with my Exilim digicam. Using a stacking software, all these subframes may become aligned and added accurately, resulting into a 4 minutes long exposure single shot with a perfect star-tracking. I reckon I didn’t use any kind of equatorial mount or motorized tracking. Just an steady tripod. Orion belt passed accros the field of view of the binoculars 3 times. In every gap, I corrected manually the FOV to get M42 inside it as longest as possible.

Orion M42 binoculars-exilim

Ganymede’s shadow

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , on 2009/08/20 by computerphysicslab

Yesterday night I had the chance to enjoy a multiple moon transition in Jupiter. Ganymede and Europa were crossing Jupiter and throwing their shadows to the big planet. Here it is an image of the event. At 23h 24m U.T Europa’s shadow was not visible yet. Io also appears at the photo but it was beneath the planet. In a minutes it would disappear.

The picture was taken with my digital reflex body (EOS Rebel XTi) and using the video capture software that converts it into a high quality webcam.

Jupiter-eclipse

Jupiter Opposition

Posted in Astrophotography with tags , , , , , , , , , , , , , on 2009/08/17 by computerphysicslab

15th August 2009 was the day that Jupiter reached its closest position to Earth. Its apparent diameter was 49 arcseconds, so this is the best time to do planetary astrophotography with the giant planet. Using the afocal technique and a Canon EOS 450d body I took 2 video sequences and processed with Registax 5, Photoshop & Pain Shop Pro.

Jupiter-2009-08-15-00h12mUT-150mm-EP14mm-450d-2videos-3x

Wesley impact scar

Posted in Astrophotography with tags , , , , , , , , , , , , on 2009/08/16 by computerphysicslab

Several days ago a comet hit Jupiter leaving a dark spot near one of its polar regions. Today this spot is still visible with a powerful telescope. Maybe if I have a high power Barlow lens I could have observed it visually. But fortunately there exist astrophotography, a technique that lets you observer indirectly what you can’t spot directly through a telescope.

In this same picture I include a Jupiter from the day before yesterday. The lack of atmospheric turbulence gave me a chance to get closer to the maximum theoretical resolution of a 6-inch telescope.

Jupiter 2009-08-15-and-16 150mm-EP14mm-450d

Jupiter selection & post-processing

Posted in Astrophotography with tags , , , , , , , , on 2009/08/12 by computerphysicslab

Yesterday I took several videos with Canon EOS 450d (Rebel XTi) to Jupiter through the no-EQ mounted 150mm reflector. The final effective resolution of every video is slightly different, depending on the weather conditions and the focus reached in this precise instant. So I have chosen the two best sequential videos and appended each other into one final with double frame size.

After selecting and appending, I used Photoshop to apply a hard sharpen, and several other filters getting different final results. Here they are.

Jupiter-selection

Jupiter & 3 moons

Posted in Astrophotography with tags , , , , , , , , on 2009/08/12 by computerphysicslab

Just some minutes ago.

Jupiter-amd-3-moons

Hommel crater

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , on 2009/08/10 by computerphysicslab

Hommel is a big crater with nice craterlets inside, a Clavius-style set, but smaller, measuring 76 miles (129 Km). It is located in the South-East area of the visible Moon face. This area is pledge of small craters. It is similar in appearance to the sand of a beach. Pitiscus, Nearch and Asclepi are some of its neighbors.

The picture was taken at 19 days of lunation, that is 4 days after full Moon. This is the best timing to get sharp images of the crater’s walls’ shadows. The image is an integration of 27 subframes, each one taken at 9 Megapixels single shots with point-and-shoot digicam Casio Exilim EX-FS10.

Hommel crater

Mare Crisium & Tranquillitatis

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , on 2009/08/08 by computerphysicslab

Two days after full moon Mare Crisium shows a nice landscape of mountains and shadows. Some of its inner crates are visible in this picture. The small crater Swift is on the limit of visibility. The big impact called Proclus and its rays are remarkable.

To take this image I used the Canon EOS 450d, Rebel XTI DSLR camera recording video subframes and later I stacked them up with Registax 5. Some small tweaks on Paint Shop Pro 9 and ready.

Mare-Crisium-and-Tranquilitatis

Full Moon

Posted in Astrophotography with tags , , , , , , , , , , , on 2009/08/06 by computerphysicslab

In order to catch the Moon, I took 4 single shots at prime focus through my 150/600 telescope. As I lack of a T-mount adapter I had to take them in handheld mode. After de-rotating them accordingly, I stacked them up with Registax 5 and removed the noise a little bit. I used the body camera Canon EOS 450d (Rebel XTi) at high resolution, low sensitivity (ISO 100) and high shutter speed 1/2000. This is the result after a blow up in saturation:

Full-Moon-150mm-450d-prime-focus-handheld-saturated

Io’s shadow over Jupiter

Posted in Astrophotography with tags , , , , , , , , , , on 2009/08/05 by computerphysicslab

As Io passes in front of Jupiter, a big shadow is cast over the planet. In this picture I took tonight, it is clearly visible the dark point of shadow in the dead center of Jupiter. At its right a small spot that you may barely watch is Io.

Jupiter-Io-shadow

In order to get a sharp image I used a Van Citter deconvolution process.

Jupiter occultation of 45 Cap

Posted in Astrophotography with tags , , , , , , , , , , , , on 2009/08/04 by computerphysicslab

Jupiter occultation of 45 Cap tonight:

Jupiter-occultation-45 Cap

Jupiter with Exilim, 450d & Webcam

Posted in Astrophotography with tags , , , , , , , , , , , , , , , , , on 2009/08/03 by computerphysicslab

Here I have integrated my best images of Jupiter taken with 3 different cameras:

* Casio Exilim EX-FS10

* Canon EOS 450D (Rebel XTi)

* Webcam Philips ToUcam Pro

jupiter-exilim-450d-webcam

Jupiter post-processing

Posted in Astrophotography with tags , , , , , , , , , , , , on 2009/07/29 by computerphysicslab

I have been lucky tonight. Good seeing to see Jupiter. Using a small binoculars between the eyepiece and my eye I could spot visually Jupiter in high definition at an effective 450x magnification. That’s pretty good for a 150/600 reflector, isn’t it?

As you may appreciate in the following picture, the GRS (Great Red Spot) is clearly visible near the center of the planet. Several details are visible in the Jupiter’s bands. The image was obtained with a non-tracking Newtonian 6-inch telescope, a 14mm eyepiece, a Casio Exilim EX-FS10 digital camera that recorded 165 subframes. Registax 5 dealt with the alignment and stacking process. Dyadic Wavelets were applied to get contrast and details. PSP9 did the post-processing. The footage was taken exactly at 2009-07-28 03:33 UT.

Here several post-processing results are shown. The first one is that I like more.

Jupiter-2009-07-29

Jupiter, Europa & Ganymede

Posted in Astrophotography with tags , , , , , , , , on 2009/07/28 by computerphysicslab

Here it is, Jupiter, Europa & Ganymede.

Jupiter-Europa-Ganymede

My best Jupiter so far

Posted in Astrophotography with tags , , , , , , , , , , on 2009/07/26 by computerphysicslab

My 6-inch reflector working over a photographic tripod, and a webcam recording the focal plane. This is the resulting image, once overprocessed, yes, I give you that.

With Registax 5 I stacked 150 subframes and then applied dyadic wavelets. Some retouching with Paint Shop Pro 9 and fractal zooming under Photoshop.

The footage corresponds to 2009-07-26 at 01:44 UT.

Jupiter-150mm-barlow2x-webcam

Lyra & Hercules constellations

Posted in Astrophotography with tags , , , , , , , , , , , , on 2009/07/23 by computerphysicslab

Last night Lyra and Hercules were located near the zenith of my suburban sky, so I could make a series of 90 shots with 10 seconds of exposure each one. My equipment was the DSLR camera Canon EOS 450 (Rebel XTi). This image sequence is equivalent to a 15 minutes long single shot. After adding them with the shift-and-add technique, and substracting a dark frame (via Photoshop) that includes light pollution I got a final picture. I have aligned (using Nebulosity 2 software) the Stellarium map of the area and created an animated gif that switchs from the photo to the map continuously. It seems every star is located correctly where it should be ;-)

Globular clusters M13 and M92 are there in the photo like 2 stars.

Lyra-Hercules-photo-map-small

Lyra-Hercules-photo-map

Jupiter’s galilean moons

Posted in Astrophotography with tags , , , , , , , , , , , on 2009/07/22 by computerphysicslab

Galilean moons are very easy to observe using some kind of instrument to get some magnification. With just a binoculars would be enough to spot the four moons of Jupiter. They are constantly rotating around Jupiter. Every day their relative distances and positions changes. Their names are Io, Callisto, Europa & Ganymede. They all have a similar size and brightness. When passing in front of the big planet, they cast a shadow over the gaseous surface of Jupiter. It is required a telescope to observe such events.

Here it is a picture I took tonight with a digital pocket camera through a 14mm eyepiece and a 150 mm newtonian reflector telescope with no-tracking system.

Jupiter-Galilean-Satellites

Light Pollution

Posted in Astrophotography with tags , , , , , , , , , , on 2009/07/21 by computerphysicslab

Light pollution in suburban skies makes nearly impossible astrophotography. Nevertheless, there exists some computer techniques to make it possible. I have used a dark frame to catch the exact pattern of the light pollution in the photographed area. The way to accomplish this is not difficult. Shooting in continuous mode the DSLR camera facing the zenith in my home window, and forcing every frame to last 15 seconds I got a sequence of subframes to be processed afterward.

To get the dark frame I do some image arithmetic with Paint Shop Pro 9: I choose 3 or 4 distant subframes and compute them using “darkest” option. This way, stars become to fade until disappearing.

With Paint Shop Pro 9 and batch processor I apply a barrel lens distortion of 17 (empirical value to correct a 18mm focal lens like Canon’s) to every subframe and also to the dark frame.

Once got the dark frame DeepSkyStacker is needed to stack the single subframes and substract the dark frame. The sideral drift of the field is automatically compensated with the intelligent algorithm that DeepSkyStacker provides.

The resulting image is surprising taking into account this is an urban sky.

Light-pollution

Canon EF-S 18-55mm barrel distortion

Posted in Astrophotography with tags , , , , on 2009/05/19 by computerphysicslab

In order to stack non-tracking subframes for widefield astrophotography, it is important to get images with no field curvature. My lens Canon EF-S 18-55mm when working at lowest zoom, that is 18mm of focal, presents a clear barrel distortion as reported in the image below. Nevertheless, it can be corrected applying a pincushion lens distortion of 15 in Paint Shop Pro. But the image border remains distorted so it is needed a crop reducing the image to an 80% of its original size.

Of course, the best solution is to stop using the 18 mm focal length for shift-and-add astrophotography. Instead longer focal is advisable like 35 mm, where the lens does not show any significant distortion in the field of view.

Another advice to get a sharp focus and pinpoint stars with Canon EF-S 18-55mm lens is to always use a focal ratio no less than F:5 and no more than F:10.  Under F:5 the lens coma aberration would mess the stars near the image border and over F:10 the diffraction would create big Airy patterns instead of pinpoint stars.

barrel-compensation-process

I have said above that “it is important to get images with no field curvature to do shift-and-add astrophotography”. I must correct it. Sky pictures are not like an image of a wall. A wall is a plane surface, but the sky is not. Actually, the sky is an sphere, the celestial sphere, that is constantly rotating around Polaris. So, the correct way to add images is not converting them to plane field, but to spherical field in the right proportion.

I have told you that pincushion lens distortion corrects the field. That is truth, but it is not appropriated to process non-tracking subframes. The subframes must firstly be corrected to show an spherical field. So the right filter to apply is indeed a barrel lens distortion, increasing this way the natural barrel that comes with the lens.

It is easy to verify this, just trying to overlap 2 distant subframes. The first and the last of the session may be optimal. Only after applying a barrel of 17 in Paint Shop Pro I could overlap successfully the subframes, preserving angles and distances between stars.

Proclus and surroundings

Posted in Astrophotography with tags , , , , , , , , on 2009/05/02 by computerphysicslab

Stacked from a video under Registax 5 and stitched with Autostitch, I got yesterday this Moon mosaic. Equipment: Meade Lightbridge 16″ and Casio Exilim EX-FS10.

Proclus and surrounding mares

4.6 days lunation Moon

Posted in Astrophotography with tags , , , , , , , , , , , on 2009/04/29 by computerphysicslab

Tonight the Moon is crescent, and high in altitude. It is a good opportunity to record our natural satellite. Terminator is almost reaching Mare Serenitatis. Mare Nectaris (actually a gulf of Mare Tranquillitatis) is now fully illuminated and its Western border walls are clearly visible.

Crescent Moon 4 Days Lunation

Tonight’s Moon

Posted in Astrophotography with tags , , , , , , , on 2009/04/28 by computerphysicslab

Here we have a 3.5 days lunation Moon. Mare Crisium is completely illuminated and some fine details may be seen, like small Swift crater (5 kms diameter). The image was a sum (Registax 5) of 10 subframes at 9Mpx using the Casio Exilim EX-FS10 and Vixen 12×80 binocular.

Moon Crescent at 3 days of lunation

Beehive cluster Wide Field

Posted in Astrophotography with tags , , , , on 2009/04/14 by computerphysicslab

I have recently bought a DSRL camera: Canon EOS 450D. Today it has shot for the first time to the stars. Beehive cluster was an easy target tonight. The maximum zoom the lens permits let us separate some of the components of the M44 cluster. The resulting image has been made of ten shots of 5 seconds of exposition each one.

Praesepe open cluster

Waxing Gibbous Moon

Posted in Astrophotography with tags , , , , , , , , , , , on 2009/04/08 by computerphysicslab

Yesterday’s Moon in phase waxing gibbous as seen through the Vixen 12×80 binocular, here it is. Registax 5 stacked 55 individual frames of 8 Mpx each. Nebulosity 2 was used to compensate the sideral movement and perform the de-rotation. Sharpening with Paint Shop Pro.

Waxing Gibbous Moon

Tycho and the South Pole

Posted in Astrophotography with tags , , , , , , , , , , , , , on 2009/04/04 by computerphysicslab

A sequence of shots to the Moon taken with the Dob Meade Lightbridge 16″ telescope has been integrated into one final image, thanks again to Registax and Paint Shop Pro. This mosaic of Tycho crater and the South Pole region is composed of 30 individual frames. The biggest crater in the terminator is Clavius. Inside it there a lot of small craters.

Tycho and South Pole

Silberschlag casts two shadows

Posted in Astrophotography with tags , , , , , , , , on 2009/04/03 by computerphysicslab

Silberschlag is a small Moon crater near Mare Tranquillitatis. What is my surprise when I observe that this crater shadow is proper of two peaks instead of a crater rim. Watch the picture and think about it. Is that normal?

Silberschlag crater

Looking for Sirius B

Posted in Astrophotography with tags , , , , on 2009/03/31 by computerphysicslab

Sirius is a difficult binary system, hard to resolve. I am trying it, and I have got one image that shows a dim star very near to Sirius A, but I think it isn’t Sirius B. I have been trying to find out which is the name of the star. I still don’t know it. Searching in Internet (and star atlas) other images of the area I see the star exists, but with no name so far. Here are the sources found:

Mizar & Alcor

Posted in Astrophotography with tags , , , , , , , , , , , on 2009/03/24 by computerphysicslab

Mizar and Alcor are probably the most well known double star in the sky. Located in Ursa Major,it is very easy to separate Mizar from Alcor, even with the unaided eye.

Sidus Ludoviciana is the faint star between Mizar and Alcor. Mizar is the brightest one, which in fact is a binary system: Mizar A & B, with an angular separation of 14 arcseconds.

Photo taken with the dobsonian reflector Meade Lightbridge 16″, using afocal eyepiece proyection. Here we see 222 shots of 0.5 seconds of exposure stacked. No tracking, shift-and-add method.

Mizar & Alcor

Where is Sirius B?

Posted in Astrophotography with tags , , , , , , on 2009/03/23 by computerphysicslab

After resolving the binary system of Castor I tried unsuccessfully to spot Sirius B. Theoretically it is possible using the Meade Lightbridge 16″, but maybe another luckier night … Integrating 200 half second exposure frames I got this result:

Sirius through Lightbridge 16

Chertan in Leo Major

Posted in Astrophotography with tags , , , , , , , , on 2009/03/23 by computerphysicslab

Chertan is an important star as a reference to locate several galaxies in the area, for example M65 and M66. Tonight I have stacked 550 shots into one image. The night has been clear, but I am located in a light polluted urban area. It has been necessary to substract the pollution from the background twice. The map shows stars up to 10th magnitude and the photo shows up to 12th magnitude.

Chertan - Photo and Map

Meteor in Canis Minor

Posted in Astrophotography with tags , , , , , , , , on 2009/03/22 by computerphysicslab

Serendipitously, I got captured this meteor while exposing Procyon in a shift-and-add series. The field of view measures around 3 degrees. The meteor track becomes cut, but it seems to be not much longer. This meteor could achieved magnitud 1 or 0, similar in bright to Procyon. Taking into account its directionality it may belong to Geminids meteor shower caused by the asteroid 3200 Phaethon.

Meteor & Procyon

M42 last night

Posted in Astrophotography with tags , , , , , , , , , , on 2009/03/21 by computerphysicslab

Last night I could enjoy a really clear night sky at Manaluna Observatory. Meanwhile some of my partners were working hard to complete the Messier Marathon, I took 3 series of no-tracking shots through Vixen 12×80 binocular to M42 in Orion.

The truth is that what I could see through binoculars was much more brilliant and detailed than the next image by far. I think my Casio Exilim digital pocket camera is a bit insensible to dim light …

M42 60 seconds exposure

Trapezium is visible as a spot. The 20″ separation among its components is too close for my binoculars to resolve it. Remember that 20″ is the apparent diameter of Saturn.

Praesepe Open Cluster

Posted in Astrophotography with tags , , , , , , , , on 2009/03/12 by computerphysicslab

Praesepe, also known as M44 or the Beehive cluster is one of the brightest open clusters in northern sky. Visible with unaided eye, even in urban areas. I have applied some filters to enhance the picture, including an artificial diffraction mask to get spikes. Using the shift-and-add technique for 1 minute I got this result.

Praesepe M44

M42 through binoculars

Posted in Astrophotography with tags , , , , , on 2009/03/09 by computerphysicslab

M42 is the brightest nebula in the sky. It becomes visible even under light polluted urban skies. I took some exposures of M42, the Great Nebula of Orion, using my Vixen 12×80 binoculars and stacked them up. No tracking, even manual. Just method. This is the result; up to magnitude 12 stars are visible and the core of the nebula is also evident:

M42 through binoculars

28 minutes of exposure for Lulin

Posted in Astrophotography with tags , , , , on 2009/02/17 by computerphysicslab

Very dim Lulin needs long exposures to get captured. With no tracking, using the shift-and-add method and the pocket camera Casio Exilim EX-Z80 under light polluted skies I got this picture:

Long exposure for Lulin

Moon & Exilim

Posted in Astrophotography with tags , , , , , , , on 2008/12/12 by computerphysicslab

Casio Exilim EX-Z80 is a pocket digital camera, very useful to make photos during holidays or a trip. But it may also be used to do some kind of astrophotography. Its maximum zoom is 3x magnification. Here we see a comparison of a Moon shot with 1x and 3x zoom. With 1x zoom some big maria are visible, like Tranquillitatis, and at 3x even mare Crisium is captured.

Moon & Exilim at 1x & 3x

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