Monday, November 12, 2012

The bolides of Teide

       After ascending to 3100m to Tenerife's Pico Viejo on last Saturday (10th of November) and descending at night, the whole party of five was quite tired (after all, the sign at the beginning of the path was marked with the "Extreme difficulty" distinction). We laughed in the face of danger. Although the initial plan was to spend the night under the stars together, the others gave in to thirst, hunger and tiredness but I could only ask them to leave me closer to the Teide Observatory: it was a night close the Taurid meteor shower maximum and some bright meteors were promised. At least for my effort I should of been a bit rewarded.

     So, they brought me to within 1 km of the observatory and packed me with blankets, warm clothes and the rest of the food and water, leaving me alone in starlight. Fortunately, Etienne was a great guy and promised to pick me up in the morning, otherwise I was supposed to walk about 10 km or so to the main road and take the bus at 16:00 back to Puerto de la Cruz. And he did, so I got a lot more sleep on Sunday :)

I was initially planning to take a long time-lapse, until dawn, but when I went to check the camera after some time I realized that some clouds/fog (basically the same thing there) passed by and ruined the whole idea. Scanning quickly through the images revealed though that the fireball (bolide) I barely saw some time earlier was indeed in one of the images. Oh, joy!! It is probably the brightest meteor I have ever photographed and I used for that a 8mm fisheye lens at 5.6, ISO 1600 on a Canon 600d and 45s exposure time. 

The winter Milky Way rises, meteors fall

     Today I played a bit with the lightcurve and reached the graph below. I took a 58x670 pixels crop of both the meteor and Castor and Pollux, plotting on the X axis the pixel number and on the Y axis the values in counts of all the 58 pixels of the line perpendicular to the meteor trajectory and the Castor-Pollux line. 

Then I averaged the values of the three CCD channels (RGB) and multiplied the result with 256, for convenience. The red shows the meteor lightcurve and the black the spatial lightcurve of the two standard stars used, Castor and Pollux.

 After performing a little statistical analysis of the values I equalized the backgrounds of the meteor image and of the standard stars to have the same zeropoint and therefore a meaningful comparison. Calculating the FWHM of the stars in pixels which allowed the transformation to arcminutes, using the pixel scale of the camera-lens combination.

 Assuming an angular velocity of 15 degrees per second for the meteor, it is then possible to calculate the time the meteor took to cross 3 arcminutes.  As the flux ratios of Castor and the maximum brightness of the meteor seem about the same, the ratios of the exposure times/3arcminutes should give us the flux ratios.

 The meaning of the values cited in the figure are: V is the pre-atmospheric velocity (km/s), the elevation h_b (degrees), the altitude H_b (km) of its start point, and the angular distance between its end point and the radiant D (degrees). 

As I mentioned I barely was it and it seemed quite (angularly) fast to me, so an Andromedid label is excluded and the Taurid origin is out of the question also from the track orientation, at least at first sight.

And that's how I got an approximate magnitude of -8.5m for this fireball :)

There were other meteors and this is the second (and last) bolide I captured on camera that night. The analysis above cannot be performed though, as the meteor track is saturated and only a minimum magnitude can be obtained in that way. 

Venus and the Moon joined the show :)

 A 100% crop of the meteor captured above. It's kind of wiggly and I wonder if it's a sampling effect or a true physical effect. 

Wednesday, October 24, 2012

Comet C/2012 S1 (ISON) & Co

The comet season is here!

After the great comet of 2007, comet McNaught and the great comet of 2011, comet Lovejoy, we might be due to another Great One. Comet C/2012 S1 (ISON) was discovered on the 21st of September 2012 by Vitali Nevski and Artyom Novichonok, working with the International Scientific Optical Network (ISON). The preliminary orbit predicts that the comet will pass 1.8 million kilometers away from the Suns center and 1.1 million kilometers above it's surface on the 28th of November 2013.

This very close approach will melt and vaporize parts of the comet and it might develop a spectacular tail, with the potential of being much brighter that the Full Moon (some predictions reach magnitude -16). It is also well placed for observations from the Nothern Hemisphere, unlike the previous two great comets of this century. But let's not forget comet Kohoutek, which was another bright hope that ended in darkness: comets are notoriously unpredictable. 

Just one more interesting "coincidence". The orbit of comet C/2012 S1 looks quite similar to that of the Great Comet of 1680. It might be that they had the same parent body, which fragmented a long time ago. Hopefully we'll have the fun Newton had while he observed it. 

Right now it is beyond the orbit of Jupiter and looks like a very faint smudge at magnitude 17.5 V, but mark your calendars for late 2013 as you might be in for the show of a lifetime!

I observed this comet last night, with the 0.5m Argelander Institute telescope (as usually).

But there are other icy snowballs visiting the inner solar system :) 

One of them is comet C/2010 S1 (LINEAR), now shining at magnitude 13.3. It brighten to magnitude 13 or so in mid-2013 an then it will slowly fade away. A much more discreet visitor than comet ISON!

The second one is Comet C/2012 K5 (LINEAR), which will brighten to magnitude 8 in late December 2012 - early January 2013.  Right now it is at magnitude 11.1. Northern observers will have the best view, as it will silently slide from Ursa Major to Taurus in this time. As the comet was moving rather fast, I had to stack the images by centering all of them on the comet: that is the reason for which the stars look like trails while the comet looks just fine :) There was a gap in the observations and that's why the star trails come in pairs.
These last two comets were observed on the 24th of June 2012.

UPDATE: 13 January 2013
Thcomet C/2012 K5 (LINEAR) has indeed brightened up to magnitude 8 during the last few months. An animation of the comet sliding among the stars can be seen below. The magnitude of the nucleus only as reported by Astrometrica is 14.8 V. 

Sunday, October 21, 2012

Wavy Perseid trail

Meteors are the blazing trails that smaller than one would expect dust leave while entering our atmosphere at huge velocities (from about 20 to 70 kilometers per second). A millimeter sized particle would produce a very bright meteor, probably not unlike the -8m one that left the trail pictured below. Sometimes these ionized gases remain visible for so long that high atmosphere winds distort them in funny ways:

The picture was taken in August 2008 during the maximum of the Perseid meteor shower from the top of the Omu Peak in the Romanian Carpathians.

Friday, August 3, 2012

The Andromeda galaxy

One chance. Once chance to get it right, with sooo many things that could go wrong! 

Almost ten years ago I could use for a night a telescope on an equatorial mount to piggyback my Canon T70 with a 200mm f/4 lens and ISO 400 film :D 

One of the targets was of course M31, the Andromeda Galaxy. It was a lot of fun, as one could not see what he's doing and manually guiding 30 minutes it's not an easy task: the slightest mistake could and would of ruined the picture.

But I kept my hand steady, my eye sharp and prayed to the control towers to divert planes from my field of view:

   Take a good look at it as we're going to crash with this giant galaxy in no time (~4 billion years!).  

Milky Way over Las Campanas

The center of our galaxy rises over the Las Campanas Observatory, with the twin 6.5m Magellan telescopes visible at the bottom of the image. It's not too far from the Cerro Tololo Inter-American Observatory and if you're around there, visit them both!

From the eye of the lama to the little horse, it's all there.

Monday, June 25, 2012

Winter cone

  The famous Cone Nebula can be found in the constellation of Monoceros and it's one of those star forming factories in our galaxy which already created a very young star cluster (the Christmas tree, NGC 2264 :) ). S Monocerotis is responsible lighting up the last remains of the "mother - gas cloud". 7 light years across (10 arcminutes) and 2700 light years distant, the Cone Nebula is part of a huge star forming complex in the winter skies, a blend of dark and excited gas and dust clouds.

 I have always wished for a Christmas Tree like this. 

Thursday, June 21, 2012

Cosmic dance and elegance

In their way through space, galaxies usually meet and interact, creating new structures. Thirty years ago a Canadian astronomer (Paul Hickson) created a catalogue of 462 such closely interacting systems, most often composed of 4-5 galaxies as closely packed together as the galaxies in the center of  some clusters of galaxies. We don't know precisely yet how many of  the galaxies in these systems are interacting and how many are just chance alignments, but studies have shown that for about half there is some physical connection involved. 

A theory suggests that these systems are on their way of creating an elliptical galaxy, so stay tuned! 

   Below, the cosmic dance brought together in HCG 44 three spirals and a small elliptical galaxy, NGC 3190, NGC 3193, NGC 3185 and NGC 3187 and signs of their interactions abound (tidal tails, disc distortions...)

Meanwhile in Pegasus, ~40 million light years away, edge-on spiral galaxy NGC 7814 elegantly displays her slightly warped edge-on disc. It is also called Little Sombrero after her closer and larger brother M 104. There are many faint galaxies seen around it and as their light passed through the halo of the galaxy is gets a little redder.

      Elegant, isn't it?

All images taken through the 0.5m Argelander Institute for Astronomy Institute in Bonn.

Sunday, May 27, 2012

M 109

Similar to our galaxy in size and shape (it's a barred spiral galaxy), our sister lies 83 million light years away towards the Ursa Major constellation.

When I first saw it nine years ago as a faint patch of light near the bright star Phecda, I imagined exactly this: 

Monday, May 21, 2012

Peak District: cold, night, spring

Twilight arrives finally in UK's Peak District National Park. Charged with color beauty, Venus trails along the Pleiades on it's journey away from the Sun: it is the last time it goes away from it before the famous Venus transit this June (more about that soon!).

  Even though it's cold, some people do look up, through the dense photon cloud of light pollution

The road to light below us (it was oriented towards West :) )

        ... and he stands below all that is timeless for most humans: stars!

Saturday, May 5, 2012

Super, super Moon!

  March 19th 2011 full Moon vs May 4th 2012 full Moon    ====    ~357 300 km vs ~358 000 km 

      The orbits of the planets around the Sun are not circular but elliptical, as are the orbits of the satellites around planets.

      Also, the Moon orbits the Earth on an orbit which can be quite well approximated by an ellipse. This means that sometimes it is father away from the Earth (farthest point being named apogee) and sometimes closer (closest point named perigee). The numbers for this would be: average distance - 384 399 km , apogee distance - 405 410 km and perigee distance - 362 570 km, only a 14% difference between the farthest and closest points! :)

      To put in in context, the Wikipedia animation below shows the Earth, Moon and their average distance to scale (with the yellow line simulating a beam of light travelling from Earth to the Moon in real time). I placed the arrow about where the perigee of the Moon would be.

                                                                                                                                                                                                  perigee   |

      Imagine yourself noticing from 100m away that a plant has grown from 45cm to 48 cm, seeing it one month after the first time. Most people will definitely not notice the size difference, but the power of suggestion is strong enough that it might really seem that it is smaller, or larger (depending on what that person was told).

        It is quite fashionable today for the mass-media to report the weirdest things and not discriminate between being informative and the opposite. We will most likely have this "supermoon effect" for the next years, just as we have the "Mars Hoax" every late august since 2003, when Mars came closest to Earth in many years (still some 55 million km away though). 

       Speaking of weird things that some people say without any kind of research whatsoever: do you remember the devastation that last year's March 19 brought? No? Well, the Moon was then even closer than now when full, yet nothing out of the ordinary happened. The March 11 Japan earthquake took place when the Moon was just leaving the apogee, being 398 000 km away.

The rise of  March 19th 2011 "SuperMoon" over the DHL Tower in Bonn, Germany

      In conclusion: enjoy the Moon, whether it's half, full or a beautiful thin crescent and while thinking that some things in astronomy can only be measured with a more precise device than the human eye.

Friday, May 4, 2012

Celestial highway

Planets wander on the sky on their own highway: the zodiacal band. Even dust in the solar system is somewhat confined to this plane and you can see it here as a lighter conical region in the middle of the image. Sometimes the planets and the Moon catch up in meetings as beautiful as this one:

Moon-Venus-Jupiter conjunction

Sitting on the caldera edge of the Taburiente supervolcano in the Atlantic ocean, a true photon feast!

Wednesday, May 2, 2012

Crab nebula and polarized light

      Besides wavelength (color), photons have other properties too: if seen as a wave their electric field oscillates in a plane which can remain fixed or rotate in time and by convention we describe this polarization state by specifying the orientation of the electric field over one oscillation.

      Polarimetry is a very useful tool for determining what kind of physical processes are at work in the light source (especially for synchrotron radiation) and the distribution of magnetic fields in it: there is much more to light than just color!

     Polarimetry color information superimposed on a "normal" photograph of Crab nebula creates the unusual picture below. The red color in the nebula comes from an arbitrary initial polarisation angle (we weren't able to find out yet the true polarizing angle), the green shows 45 degrees more and the blue is with the filter rotated by 90 degrees compared to the original position.

The image has been made by me (color and luminance data) and David Muelheims (polarized data), in Bonn, Germany.

        And although "popular wisdom" might tell you that the human eye cannot distinguish between polarization states, it's not really true, as Haidinger found out many, many years ago :)

Dubna наукоград: noctilucent!

A rather cryptic title for a post with some clouds over a lake or something, right? 

     Dubna naukograd, the science city! It is an international center for nuclear physics and so much has been done here (and is being done here) that we even named an element after it: Dubnium (A=105)!
     While spending the summer there I had the chance to do two things: live in a perpetual state of light and twilight (the sun was barely setting before going up again, Dubna is quite up north) and witness magnificent displays of noctilucent clouds. 


       What clouds?!? While taking an airplane sometimes people might say that "you're above all the clouds!"; this is quite far away from the truth, as there are clouds "slightly higher" than where the usual stratospheric planes fly, at 10-12 km altitude. These special clouds are so high that are way beyond stratosphere and at the edge of space: ~85 km high, in the mesosphere, just below the mesopause. It's very cold there (-125 Celsius degrees) and guess what: we don't really know what they are and how they form. To solve this, we launched a satellite, the Aeronomy of Ice in the Mesosphere (AIM) which started it's mission quite recently.

      Wispy, electric blue, at the edge of space and seen at the end of twilight close to the summer solstice in regions as far away from the poles as 45 degrees latitude, they are a joy to watch and observers gather their sightings and more information here. As the climate gets warmer, the mesosphere gets colder and they are becoming a more common sight closer and closer to the tropical regions of our planet.

   ...and yes, these pictures are taken at midnight! :)

Tuesday, April 10, 2012

The anti-twilight arch

What can a belt of Venus do to an already beautiful planet?

This phenomenon forms where Earth's shadow is projected through our atmosphere and as explained by it's Optics Picture of the Day page it's a combination of the back-scattered red light and deep blue anti-sunward sky.

The moon was riding just on top of it as you can (barely) see in the large version of the image and just a few hours later I was the fortunate witness of the 2008 Perseid meteor shower :)

Clouds and bows

The APOD description for May 4, 2010 of the first picture below reads: 

 "If you tried to enter this hall of fog, you would find it dissipates around you. The hall is actually an optical illusion created by sunlight backscattering off of a cloud passing below the peak of the mountain from which this picture was taken. Known as a fogbow and similar in some ways to "the glory", the phenomenon is sometimes seen from airplanes. The ring's center appears near the image bottom where the shadow of the photographer is visible. This shadow would likely change as clouds passed, creating a faux moving giant known as the Brocken Spectre. In the picture, several concentric rings of the fogbow appear to create a hall for this mountain king. The cause of fogbow supernumeraries arcs and glories have only been understood recently and are relatively complex. Briefly, small droplets of water reflect, refract, and diffract sunlight backwards towards the Sun. Atmospheric backscattering phenomena have a counterpart in astronomy, where looking out from planet Earth in the direction opposite the Sun yields a bright spot called the gegenschein." 

Check the links to the awesome website of atmospheric optics for more explanations of this wonderful world of interactions between photons, droplets and ice crystals. 

APOD mention of the Brocken Spectre Giant reminded me of this:
There is the true Giant, as apparently Teide has the longest shadow on the planet (over 200 km) and I was just at the top of it.

  Another image of a fogbow (cloudbow) taken from Taburiente's caldera edge

It's amazing how a cloud passing by can create such beautiful phenomena: I was completely engulfed in the clouds just a few moments after taking this picture. Some more seconds and it was all clear again!

Wednesday, March 21, 2012

Cerro Tololo Inter-American Observatory

The place to be. 
No light pollution, clear skies most of the times, large telescopes, very friendly people and great food, silence, zenith galactic center, southern constellations, Pacific, Andes! 

Blanco 4m telescope is the second one from the left: it is now equipped with a monster CCD camera, called "Dark Energy Cam" which samples well the 2.2 degree field of view with it's 570 megapixels.

Light pollution Fagaras

Light pollution is the greatest enemy of today's ground-based observational astronomy. In the highest mountains of Romania, the Fagaras part of the Carpathians, one would expect to be far away from this disgraceful waste we are producing. Yet, it is omnipresent...

    The red light on the snow comes from a signal beacon installed on a communications tower nearby and the view is towards Sibiu. Just comparing this image with the sight from an unpolluted spot on Earth makes us sad....

Tuesday, March 20, 2012

M 95 supernova

...and we have another bright supernova! Colloquially called PSN J10435372+1140177, this time it is in M 95, a barred - spiral - ring galaxy in Leo and it's brightening fast. We don't know yet what kind of supernova is it, but more observations will let us know soon :)

Let's also wait for the IAU to officially annnounce it, it has been discovered or a few days already by the Italian Supernovae Search Project.

Images taken together with Dominik Klaes, Daniel Lenz and Katharina Sendlinger.

Sunday, March 11, 2012

Horsehead nebula

B 33 and IC 434

      It's winter and you look again towards Orion and it's famous belt stands out as usually: there is no other asterism on the sky that is as conspicuous as the belt for me: Alnitak, Alnilam and Mintaka are 2nd magnitude stars quite far away at ~ 1500 light years average distance. 

     If you live in a very, very clear of light pollution spot on Earth and you have a telescope at hand, sliding south of Alnitak will bring into view one of those emission nebulae I was writing about: it's IC 434. It's a long   pinkish nebula with a bright rim, which if you can follow might seem interrupted at some point by a dark spot. Well, that dark spot is B 33, also famously called the Horsehead Nebula for some reason :). The color is given by the nearby (quite some light years away still) Sigma Orionis ionizing the hydrogen in the nebula. Especially bright, massive stars affect their environment a lot!

     It is a very difficult object to see in anything less that ideal conditions, but don't give up if you have a limiting magnitude better than +6 and a good telescope. It took me quite some patience (a couple of hours) to finally detect it with a 8" Newtonian under +6.5 skies. Totally worth it under the -10 C at the time.

    There are a few stars forming at the base of the horse (funny expression, isn't it?) but one day under the pressure of Sigma Orionis and with the help of the intense magnetic fields already in the region, the whole Horse will shine!

Tuesday, February 28, 2012


Observatorio del Roque de los Muchachos

El Teide from La Palma

Cherenkov realm


"Band picture": the team!

Marcel, Oana, Ovidiu, Alex, Alin, Dana, Toma

MAGIC is magic

DOT (.) - Dutch Open Telescope, ofcourse

The road to Sgr A


Observatorio del Teide (III)

Most likely Gran Canaria

The motherships

Western view

 Eastern view

Solar telescopes sleep at night

Fire stone near the fire mountain