March 2007

2007.03.17
Local:Pulo do Lobo - Serpa

Messier Marathon II

The Messier Marathon is an exercise that at some occasion on the amateur astronomer' s experience seems meaningfull. The Marathon consists on observing all the 110 deep-sky objects from the famous Messier's list of false comets throughout one night.

There are no rules or obligations on executing a Messier's Marathon , for a beginner could seem a gigantic task on having to locate and identify 110 targets, and it is so to whom is not familiar with the sky, each one do as well as (s)he pleases, even so, I find the use of digital circles to aim the telescope (“goto”) voids one of the purposes that this kind of exercice provides: to deepen the knowledge of the sky and the localization of its wonders. It is an excellent exercise of revision, endurance and a party if in the company of friends.

A Marathon has more to do with the extension of the observing's list then properly with observation. Typically less than 1 minute is expended on each target and that if it is particularly interesting or a favourite one. For detailed observations, other and more paused nights exist. All the objects are visible with 50mm and up aperture with magnifications of 15x and above when under a dark sky. Some objects need more magnification to be distinguished, like many of the small galaxies in the list. The aperture follows the trend of diminishing with the more experience. The next one will be probably with a 70x16 binoculars.

The magnifications to use should be the lowest possible and by using an wide-field eyepiece it is possible “to score” two or three Messiers and even some bonus in the same field. In this case in particular, the eyepiece used was an 24mm panoptic with a Sky90 that resulted on 21x magnification and a 3 degrees true field , occasionally used a 9mm nagler (56x 1,5 degrees) for the small globulars and a nagler zoom 3-6mm for the planetary nebulas and planets (83x-167x).

For the a second time I've runned the marathon under the dark skies at Pulo do Lobo (south east Portugal). At the beginning of the night the clouds had vanished completely . The SQM scored the absolute record of 21.60, darker than Bragança or Serra da Estrela , but unfortunely the sky transparency was quite low, up to 5 degrees above the horizon it was practically opaque, condition that proved to be problematic at the end.

The Messier's Marathon has too many dead spots to keep me entertained aiming the telescope for almost 12 hours, that's because I know the localization of half of them (that it seems a great feat but it isn't).
So I decided to add some targets with the help of Karkoschka's suggestions , that plots the all the Messier's 110 and 140 objects more from which about 100 can be observed at 37-39 north latitudes , including the south extremes Centaurus A , Omega Centauri and NGC 55.

Follows the night report

The Fishing Labour

The marathon started just after the Sunset.

This was the time to align the finder on the bright planets like Venus or Jupiter if above the horizon and all setup and ready to begin the long night until the Sun appears on the opposite side.
It will be the balance between the target's rising and setting and the night's extension that will determine the difficulty (or the impossibility) to detect the objects on the extremities of the list. It is extraordinarly rare to be able to conjugate the above conditions with a clear night, a dark sky without Moon and all that happennig on a weekend. This Saturday surely was not optimum day.

At the beginning the only real challenge is the spiral galaxy M74 at the Fishes. This otherwise pretty galaxy is already extremely faint with small apertures , even more when observed during the crepuscular time, and with the zodiacal light worsing the contrast even more. It must be tried to observe this galaxy from the moment it can be triangulated with the stars, but not insisting too much, and proceed on observing the rest of the first dozen of the list and returning to it as necessary. This time only at sixth time and also the last one of the first dozen to be observed.

The sequence isn't the most important but keeped the eye on these three galaxies: M74, M77 and M33. The Andromeda's trio M31/M32/M110 and Orion's pair M42/M43 and neighboroud NGC 1981 and nebula NGC 1973 “Running Man ”), giving a quick look to the open clusters M52 and NGC 7789 at Cepheus, M34 and M76 at Perseus and M103 in Cassiopeia, region where can be found the double cluster NGC 869/NGC 884 and the “ET” cluster NGC 457.

count : 12+6

After this first dozen, entered on a more paused sequence and already quite far from the crepuscular light . All are relatively popular and bright.

Follow, the Pleiades (M45) and see how was the transparency on the Mérope (not particularly good), the first catalogue nebula M1, going up later for the Coachman's M37, M36 and M38 clusters and also the M35 in Gemini (and small companoion NGC 2158) not forgetting the “Eskimo” planetary NGC 2392. Returning to Orion for M78, give a quick look at Alnitak's nebula (NGC 2024) and to go down below to the Hare scratching globular M79 off the list.

Already near to the central meridian found the M41 in Canis Majo and higher up the Unicorn's M50 and then going down a bit at Puppis for the M93 and the fabulous pair of clusters M47/M46 (this last one with the planetary NGC 2438) and going up a bit to right one of the Messiers that never I know where in which part of the sky is located : the open cluster M48. Finally finishing with M44 and M67 cluster in the Crab.

As everything runned well, at 21:00 hours (48 minutes after astronomical crepuscul) one quarter of the list was fulfilled and the central meridian crossed by more than one hour having time for a short break and letting the sky rotate for about one hour.

count: 28+10

The Foreplay

Nature arranged a good way to provide a warmup to the approaching Inter-galactic battles, and nothing like the Lion's Messiers as a good skirmish. Started with the pairs M95/M96 and M105/NGC3384 and then jumped for the animal's posterior part for the pair of M65/M66. Not forgetting to collect the bonus NGC 3628 close to the former, then a jump to the Lion's mouth where it is the galaxy that Messier incredible failed to include NGC 2903. Still time enough for the NGC 3606 and NGC 3344 and also extra planetary bonus Saturn.

Next, moved to another region of the sky crossing almost half of it to another great predator territory : the Bear, with the pair of galaxies M81/M82 (where it can be seen the small satellites NGC 3077 and NGC 2976), the planetary M97/ M108 galaxy, the extremely well illuminated M109 , and by all means the M40 double star. Here are also some bonus to gather: the NGC 2683 in Lynx and the NGC 2403 wich are a beautiful prize for the most dispatched. Not forgetting the challenge on NGC 2841. Heading north we have the controversial M102 and a quick hop to the bright “cat's eye” NGC 6543.

Then pointed to Canis Venaciti starting on the M106 the descent galaxy to galaxy down to it's beta star , passing by the NGC 4449 and finally NGC 4490, from there is one small hop to the M94, M63 and before going up a jump the complicated and streched NGC 4244 (this one a half-guessed super-bonus). The M51 and friend NGC 5195 are a traditionally popular target as well the M101.

Follows two globular clusters : the M3 still in the Dogs and the M53 already entering in the Coma Berenices and the bright M64 galaxy at the Great Cluster door. Before attacking the next stage, accumulated some of the last pack of bonus of this marathon: pair NGC 4656/NGC the 4631 and the four brighter galaxies at Coma: NGC 4725 NGC 4559 and NGC 4565 and the finally small eliptical NGC 4494.

After this warm-up the clock marked 23:00.

count: 48 + 31

The Labour of the Hairy Virgin

This is one the most labourious moments of the marathon.

The aperture will dictate the difficulty to pass the test of the Virgin. Curiously, the lack of aperture can be an advantage, because it excludes dozens of galaxies that can appear in the field of a 8" or greater aperture, causing somewhat complicated identification. Using a small aperture leaves no doubts on which the Messiers are . The best a strategy is to start where s the virtue is, in the middle. In this case right between the stars Lion's Denebola and the Virgo's Vindemiatrix (who makes vindimas) that marks the spot where the bright pair M84/M86 is located. From here will be always a safe and an easy to find starting point for almost all the galaxies of this area. Here only passes who knows.

Below we have the not less bright M87 and little more than a degree the M89 that can be seen in the company of the M90 and the M58 just below, from the latter we leave to the pair M59 and M60. However returned to the pair m86/M84 because I was already lost. Restarting, I redone the waypoints M87-M89-M90 and then going up two degrees to the a faint M91, which shares the field with the M88.
For the M98 and M99 I used a near 5 magnitude star right in the middle of these two galaxies that are not easy targets, following the bright stars to the M100. This set is quite more laborious than previous paragraph makes it to believe. Some galaxies were several times observed, and for several occasions did the hop to be certain that I was on the right galaxy. With 90mm they all look similar in form and brightness and equally little interesting, getting worse that most are eliptical galaxies.

It was now time to search the isolated galaxies like M85 in Coma that is close to another magnitude 5 star, the M49 that makes a right triangle with the Virgo's Beta and Delta, collecting the only bonus that I dared to add on this phase: the galaxy surronded by two stars NGC 4526. I finally finished this region with the M61 that makes a triangle with the Virgo's Delta and Gamma.

Later after the rush phase, descended the horizon to the always popular M104 ("Sombrero"), then even belower to the Crow to a section of the enormous Hydra where are located the faint globular M68 and finally to the catalogue's lowest galaxy, the M83.

count: 67 + 32

After this test it is time to eat something, to take a snap or go to other activities such as the astrophotography. Below is a souvenir from this night. I thought to take a image of Markarian's chain, but is too much beat up target, so pointed a bit higher to a field where can be found the M100 and the M99 galaxies. I also searched for the Omega Centauri with my night companions , without great luck due the low horizon was unpenetrable.

The Beast Labour

After the big break, I restarted without at slow pace, because the Summer constellations still a bit delayed to a more convenient altitude. This segment has some box-office successes like the globulars M5, M13, M92 and the planetary nebulas M57 and M27 and others of less frequent visit the clusters M56, M29, M39 at Cygnus and M71 in the Arrow. The additional objects were the “North America” NGC 7000 (very little contrasted with filter UHC) as well as the “Veils” that also were practically invisible and finally it “blinking nebulas” NGC 6826 - this time didn't blink...

Returning to South to the Ophiucus's globulars, starting with M12 and a little more to the side the M10. M14 makes a flattened triangle with the Gamma and the Nu of this constellation stars . M107 is a direct shot next to Zeta and the M9 also near Eta and in also planetary bonus: Jupiter.

The Scorpion's head was already well raised along with the M80 and below close to the Antares the M4, concluding the sequence with last the Ophiucos's globulars M19 and M62. I finished this section with the clusters M6 and M7 on the extremity of the Scorpion's tail .

The clock read 03:35 and I made a brief pause to prepare myself for target's cascade that followed.

A big chain of objects that followed started well high in the constellation of the Shield with the clusters M11 and M26, descending to M16 “Eagle Nebula”, M17 "Swan Nebula", the M18 cluster , passing the M24 star cloud, going on side to M25 and on the other side to M23. Descending a bit more arrived to a very familiar region of the M20 “Trifid Nebula ” and M8 “Lagoon Nebula ” and the close M21, all these in the same eyepice field. On the way of one of the favourite globular, M22 is the cluster M28. I needed to wait a bit more for the small and faint globulars at the Teapot's base M69, M70 and M54, where the middle one gaved a bit of a fight.

The transparency on that sky's region was extremely low, but the calendar was integrally acomplished to this time : 04:43

count:103 + 36

The Last Labour (and dying on the beach)

The last Septet finally arrived.

At this phase there is no place for doubts: I should have trained the triangulation of these objects with the minimum possible stars, that is something that never I do and later regret. The end of the astronomical night was very close, with the stars disappearing fast. Here the aperture gives a sincere advantage, allowing more magnification in order to increase the contrast that lowers at fast pace.

Only the M15 globular in the Pegasus and M2 in Aquarius (in extremis by 05:05) were detected, even so I attemped the remaining M55, M75, M72 and M73. The M30 was hopelessly below the horizon.

final count : 105 + 36

As a reminder to myself, below is what would have been the itinerary for the not-detected objects:

M55 is the one to watch out , is not only one of the lowest altitude Messiers , it is also the most isolated of the list with very few stars to triangulate it. Despite it's cheer dimension is not especially bright and due to the low altitude and consequent atmospheric extinction it can be very complicated to observe with a small aperture.

Already on the way of Aquarius and Capricornius get the small and faint M75 which even in normal conditions is not an candy. In Aquarius are the M72 and the M73's 4 stars, if have time (which I doubt) to see also Saturn Nebula a littel higher up and finally the last one: the always illusive globular M30 at Capricornius.

The End

report written and translated with the music of:



2007.03.03
Local:Atalaia (Montijo 38º44N 8º48W)

Total Lunar Eclipse

As predicted the Moon passed trough the a shadow projected by our planet.
This was perhaps less dark lunar eclipse I have witnessed so far. In the Danjon's scale of eclipse brightness the estimation fits very well in a value between 3 and 4, especially having in consideration the brightness of the most illuminated limb.

This eclipse was passed with the company with all whom had been at Atalaia's site on this night, beyond the company also borrowed a battery to substitute my own that delivered it's soul to recycling.

The Moon was born with all setted up for a great ecliptic marathon. Practically all clear sky at the area, with only some fast clouds passing by until practically to the end of the ummbral eclipse. Lots of humidity and mild air temperature.

The umbral phase of the eclipse was initiated and a difuse darkening a the lunar limb's South east became immediately notoriius . I essentially followed the the shadow advance using the 7x50 binoculars, starting to see appearing each time more stars, that becamed visible with the gradual moonlight attenuation. One of nearby bright star (the magnitude 5 59 Leo) would be occulted after the end of the totality (in the image above is that little point about to be occulted at left).

A good way to see the shadow evolving on the lunar surface is using a great aperture telescope . Without a doubt the sights that I gave for several times on the Alberto's 15" were spectacular and had due the eclipse truily invulgar. Note to myself to not forget to take mine 20cm for the next one.

As in all the rare celestial events, there is always some kind of strangeness to watch the Moon passing through “impossible” phases on this hemisphere or in both, seeing the stars gradually to appear and one hour later coming back, or yet to see in the binoculars a full moon encircled by stars and the eyes not be completely blinded. This eclipse seemed me the most colorful yet, with hues that went from white to bluish gray, yellow and finally all way to the orange.


Moon at greatest eclipse 23:21 UT
(clique na imagem - click on the image)

 


Moon 3 minutes after totality 00:02 UT

Eclipse's Times (Guide8):

- Equipment used to capture the images: Takahashi Sky90 and a Nikon D70 on the top of a Takahashi P2Z.


Other Total Lunar eclipes at Pátio: