June 2007

2007.06.30
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Venus and Saturn II

A somewhat rare conjunction of planets happened today at the end of the day.
The pair in cause is sui generis with both showing their typical characteristics: the crescent phase of Venus, and the “ears” of Saturn. Although separate by 3/4 of 1 degree, this separation is immense when compared with both planets apparent size, if we have in account the Saturn's rings thwy were practically equal with about 33-35 seconds of arc (80x its separation).

Both were visible on the 16x70 binoculars before the Sunset . The difference of magnitudes was enourmos, Venus 100x as bright, but the difference is quite well processed by our vision without any ocurrence of saturation.
But to photograph such disparate brightness intensities is quite another story. Below it is a photograph that resembles on what could be observed through the binoculars, in this the case just 2 minutes after the Sunset. The necessary critical exposure to not allow Venus to saturate and to regist its phase, and simultaneously to pull out from the background brightness the fainter Saturn needs the aid of a good deal of luck.

Later, clouds comed back covering the sky and I tried to use them as a natural filter (H2O) that hopefully would simultaneously shadow Venus and not cover Saturn, in an attempt of them to take a photograph when the brightness of both was similar. Below it is the better of the lot.




2007.06.29
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Venus and Saturn

Today at the end of the day.





23/06/2007
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Pátio CCXXII

This home session started at 0:00 UT (local 01: 00 ) of Saturday, having ended about 2 hours later due the increase of the cloudiness . In the session's beginning the Moon's Quarter was very low, contributing much less to the sky brightness than the local light pollution. Flanked by the immense from so close, cupula of light from the city of Leiria at South and surronden by buildings , the only sky spot that survives circulates 15, 20 degrees around the zenith as the only window for the remaining Universe. The SQM marked an desapointing 18,82, value that can be considered awfull for the practice of visual astronomy other than planetary or from the couch, however the visual estimate at Ursa Minor region still had a hopeful 4,5 magnitudes. The sky was practically clear with some clouds that occasionally hastily passed by. A Summer's night with a pleasant temperature.

Despite the the unfavorable scenario, I decided to bring my estimed 20cm dobson to the patio, together with a pair of eyepieces, the 24mm panoptic (51x 1.34º) and to 9mm nagler (131x 0.6º) and also the Sky Atlases Karkoschka (3ª edition soon), Millennium Star Atlas and the Pocket Sky Atlas.

I started with a small tour of diverse random targets while the telescope balanced to the outside temperature, and make some time so that the Swan constellation apper above the roof of my building. I started in its “preceding wing”, the higher one.

The Planetary nebula NGC 6826 (see image) also known as “blink nebula ” this time did not give or I didn't have the patience to see the peculiar effect. Already denounced at 51x with the Pan24, at 131x showed a elongated and relatively homogeneous surface , but little else to write about. This nebula is located in the middle of an interesting stellar context , some pairs of stars can be found in its vacinaty , from which stands the bright 16 Cygni that is a true double system of yellow G dwarf stars very similar to our Sun, situated at 70 light years light and where for the first time in a double system, was found a extrasolar jovian type planet . This binary system is in the Kaler's book , The Hundred Greatest Stars, where the author makes some curious deductions like: “To the 16 cygnians the second Sun would be twice as bright our Full Moon”, or still the reason why the young Luke Skywalker's home planet Tatooine with its two Suns is almost an impossibility...

Following some of the objects plotted on the same page of the Pocket Sky Atlas I passed by three open clusters in the region. In NGC 6811 about 10 and 11 of magnitude 40 stars could be counted uniformly spreaded on a diffuse area of unresolved stars. NGC 6866 showed less stars and was slightly smaller but with a proeminent chain formed by the brighter ones. Finally arriving to NGC 6910. This interesting cluster only at half the degree from Swan's gamma Sadr (in the heart/chest of the Swan). A dozen of stars draws a form of an inverted Y, two very prominent 7 magnitude stars , that turns this cluster somewhat appealling.


NGC 6910

Moving to the West "wing" I passed by the small but bright planetary NGC 7027,, already distinct 51x and oval at 131x without however having noticed any other detail.

The 61 Cyg is a star, or better, a pair of stars that is notable for several reasons. First and the most immediate one through any telescope. it is of being a beautiful golden/orange pair of stars . But beyond its intrinsic beauty has a great historical importance.

It was the first star from which the real distance was measured with some precision. In 1838, Friedrich Bessel announced that it presented a parallax of 2/3 of an arcsecond (0,66 "), the current formal parallax value is half of that about 0.287.13 ". This results in a distance of 11.359 light years light, being 12th and 13rd stars close to our Sun.
It is a visual double star consisting by two orange stars of similar magnitude and tonality: 5.20 (K5) and 6,05 (K7) that they are also slightly variable as is the case of almost all the stars of this class. Its orbit was calculated 659 years with an average distance between stars of 85 AU, and because its big eccentricity (0.48) the orbit varies between 51 AU and 119 AU, beyond and almost the triple of the Pluto's orbit (40 AU).

Another interesting characteristic is for being the only red dwarfs (low luminosity and cold) that with combined magnitudes to be naked eye visible. With luminosities of 0.08392x and 0.03882x of the Sun, they are indeed very little luminous stars that obligatorily have to be enough close to us to be visible with such bright magnitudes.

And finally its notourious annual motion in relation to other stars that that he places them in 7th and 8th in the fastest stars and 1ª and only visible with a naked eye (again with the combined magnitude), apparently moving about 5 " per year. This fact originated its anglo-saxonic nickname “Piazzi's Flying Star” (“Flying Star of Piazzi”) in honor of Giuseppe Piazzi (1746-1826) from the Palermo's Observatory that first measured its proper motion. The proper motionis a good sign of proximity, so Bessel chosed this star as good candidate to get a observable parallax. A really beautiful and interesting pair of stars in all aspects.

Currently this binary system is opening it's separation: 2000.0 202.1º 30.74" - 2010.0 200.4º 31.34" - 2020.0 198.7º 31.89"

The "Egg nebula", AFCRL 2688, PK 80+6.1, is one of tht sky's strangest planetary, being currently classified as an bipolar proto-planetary , intermediate stage to a formation of a planetary nebula. I never thought that it would be possible to visually observe such rare and faint object from the Patio's sky , with photographic magnitude of 13.5, visually seemed me although of the conditions of accessible observation. Two years after having made an image and a small description, I recalled having some difficulty to place it in the field of my passed atik-1hs, that even with a generous exposure its nebulous nature wasn't very apparent.
This time I had the MSA's help , cart 1147 to place in the field. The cart didn't have many stars for reference, except an 8 magnitude orange SAO 70809 and another one of 10 magnitude, those were enough to have the certainty to where to look at.

I initially suspected it with 131x as one faint double of 12-13 magnitude stars and made an sketch of its position and orientation to later confirm if really had detected it. Without any present nebulosity, it remained stellar and it could well pass for an ordinary pair of faint stars. The UHC filter did not help, quite the opposite. After detection even at 51x it was possible get some flashes of something on “right” position and made the below sketch to confirm with the Guide8 planetarium that what observed could only be the planetary and not two stars, and it came to happen therefore on that position only 15 and 16 of magnitude stars exist , completely impossible targets with an 20cm aperture and such sky conditions.


AFCRL 2688, PK 80+6.1




2007.06.21
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Solistíce, ISS and Atlantis

The adjournment of the Atlantis re-entry allowed another parade of these two machines.
On the photograph we can see the tracks left for both with 53 seconds exposure, passing by the Ursa Major's stars Alioth, the visual pair Alcor/Mizar and Alkaid. The different tonality is interesting, being the Atlantis bluish, and the also less bright than the yellowish ISS. The Atlantis was notorious brighter than the Arcturus, surely with negative magnitude. The ISS seemed almost as bright as Jupiter (maybe because the new solar panels), both brighter than Heavens-above forecast (- 0,9 mag).

Also today was the Summer's solstice. From this moment until the o Winter's solstice, the nighttime wil slowly grow.

Photograph taken on a fixed tripod and a Nikon D70 with an 50mm objetive. Even with such short focal distance and exposure the stars dragged, for such exist a process “to straigh up " stars using PS, here described to serve as a reminder to myself because I keep forgeting it:

I've done this process two times. The first time to take off the stars and to leave the tracks and second to round the stars, finally adding the two results. This processing is extremly destructive on the faint stars, but the ones that were left fullfilled the intended purpose.


ISS and Atlantis 21:08 UT


2007.06.18
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Venus and Moon

Excepting the Sun, the two only celestial bodys that can be seen in broad daylight had met today at the beginning of the afternoon.

This close conjunction was perfect naked eye event, even at minimum separation (2,5') at 14: 32, 15:32 local time, Venus shone well detached but only at the telescope (20cm dobson 34x) was possible to observe its phase that was quite similar to the Moon. An impressive sight, having in account with the Sun shining in all the strenght just at two well measured stretched hands.

It is a common idea that it is not possible to observe planets during the day, Venus and Jupiter are sufficiently easy to see with the naked eye, it is just needed a small aid of the Moon to know where to look.

Other diurnal conjunctions at Pátio:

 


Venus and Moon 14:44 UT

The image below shows the curious Venus phase , with the caracterísitic form that cúspides (extremities of the phase) aren't as acute as of the Moon due to atmosphere existence, resembling a celestial garlic tooth.


Venus and Moon 15:02 UT


2007.06.12
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Venus and Beehive

Today a bright Venus made a visit to the great open cluster M44 at Cancer, also known by “Beehive” or "Praesepe", because when viewed through binoculars it resembles a swarm of bees.

For a curiosity purpose, Venus shinning at a -4,3 magnitude is equivalent in brightness to a Type 1a supernova that it blew up (at) 33000 (light) years ago*, ignoring the interstellar absorption. But in the truth it could never be a member star of M44 that is located much more closer at 577 light years according to Hiparccos, or 600 light years according to a recent “paper”.

Mathematical curiosity aside, even with the intense the luminous pollution and cloudiness, it was an interesting sight on the 16x70 binoculars where both were well framed on its 4 available degrees, even with a pine tree giving a terraqueous touch to the scene.

* using the distance-modulos formula m - M = 5 log(d/10) we can reformulate it to d = 10^((m - M + 5)/5) - with m=-4.3 (Venus's apparent magnitude) and M= -19.33 (absolute magnitude of a type 1a supernova) resulting 10140 parsecs (33000 light years).


Venus and M44 22:05 UT
(clique na imagem - click on the image)


2007.06.03
Local:Pátio (Leiria 39.75N 8.82W alt:60m)

Sun

I had during some years observed/photographed almost daily our Sun . In the years the 2002-2005 the Sun had its solar maximum magnetic activity that is accused by the more or less existence of sunspots on its surface.

Currently the Sun is already slowly going to the ascending phase to the next Solar maximum, having inverted its magnetic polar region, with the most notourios consequence the greater incidence of active groups above its equator.


Sun 14:02 UT
(clique na imagem - click on the image)


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