September
Local:Pátio (Leiria 39.75N 8.82W alt:60m)
Total Lunar Eclipse
The night started quite well, with a clear sky only interrupted by some hasty clouds. Excused to say that the meteorological conditions were getting worse as the eclipse hour was approaching , even had some pretty strong showers. But unstable a meterologic conditions are always better than a bad steady meteorological condition, it gives always some hope.Always with an eye on the Meteosat images, I've tried to forecast possible cloud holes that were approaching from the West Portuguese coast that could pass over my pateo (backyard). Happily made some right and on others I was also wrong! Nothing could foresee the one hour cloud break during the period of the totality, I do not know if it was only local, but on the little available horizon of my pateo, the sky was practically clean and clear.
Fortunely on the few opens that appeared it was possible to regist with moderate comfort the images below. Until arriving the big surprise of the GREAT one.
Visually, this was darkest lunar eclipse that I had occasion to appreciate, at least in more informed way, having a value on the scale
of eclipse brightness of Danjon between 1 and 2. With naked eye it was possible to observe tonalities that went from the brownish red, passing by the copper orange to yellowish on the opposite limb.
It is always a strange sensation to see a full moon surronded by stars. The photograph of the eclipse's maximum contains stars down to 10 magnitude !, the sky was dark as much the light pollution allowed. The binoculars were my favorite instrument, the low magnification renders more vivid colors, and the wide field views adds much to the natural strangeness and rarity of the views of an eclipsed moon.
Will be more partial and penumbral eclipses on the next two years, but next total eclipse will only happen at March 3rd 2007.
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| Lua em eclipse resolução - resolution: 2" instrument(o):Takahashi SKY90 f/9 (800mm) câmara: Nikon D70 (clique na imagem - click on the image) |
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| Lua em eclipse máximo 03:04 UT exp: 10s iso 400 resolução - resolution: 2" instrument(o):Takahashi SKY90 f/9 (800mm) câmara: Nikon D70 Takahashi P2Z (clique na imagem - click on the image) |
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| Lua em eclipse máximo 03:04 UT exp: 10s iso 400 resolução - resolution: 2" instrument(o):Takahashi SKY90 f/9 (800mm) câmara: Nikon D70 Takahashi P2Z |
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| Lua em grande campo exp: 8seg. iso 50 câmara: Canon G1 100mm Takahashi P2Z |
13/10/2004
Local:Pátio (Leiria 39.75N 8.82W alt:60m)
Slender Moon and Mars Conjunction
A dawn of rare serenity around these parts that offered the chance to capture a conjunction of the Moon with only 0.9% of illumination with
the Mars planet, separated by only degree. The Moon was less than one day of being New (only 20 hours and 40 minutes) being easily observed with the binoculars since the apparent altitude of 3 degrees (06:10) until a little more than the 4 degrees 5 minutes later, this despite the always present fog and the shining Sun only 11 degrees below. I also tried to observe it visually but me it was not possible to detect it.
The first image is with "the natural" colors, and the second was equalized to show better the conjunction with Mars planet and the Earthlight on the non illuminated surface of the Moon.
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| Lua a 0,9% e Marte 06:12 UT exp: 1/15s. iso 200s resolução - resolution: 4,2" instrument(o):Takahashi SKY90 f/4 (360mm) câmara: Nikon D70 (clique na imagem - click on the image) |
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| Lua a 0,9% e Marte 06:14 UT exp: 1/15s. iso 200s (equalizada) resolução - resolution: 4,2" instrument(o):Takahashi SKY90 f/4 (360mm) câmara: Nikon D70 |
09/10/2004
Local:Pátio (Leiria 39.75N 8.82W alt:60m)
Around Vega
Small tests session with the old Toucam Pro that recently was modified for long exposure. This camera is still is in the “original box” and by no means cooled, if not being able to exaggerate ont he gain nor with the exposures timez. Optimum balance was at 20 seconds with 40% gain.
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| Philips Toucam Pro The recently modified original Toucam |
The 20 second dark frame isn't that bad, having in account that was working without any refrigeration.
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| "dark" exp: 20sec câmara: Toucam SC 40% gain |
I going to try the “RAW” mode next time, as below dark frame pronuncies, the stars will be sharper if the “mixture” of the bayer matrix is donne afterwards, in this case the image was gotten using CFA feature of Iris.
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| "dark" exp: 20sec RAW câmara: Toucam SC 40% gain |
The below images below of Vega had the purpose of verifying the camera's sensitivity, that is about 14 stellar magnitudes with just 20 seconds, under 4 magnitude sky. With the non RAW format, I believe it is impossible to obtain one stars pixel, and also present the artifacts, such as “ears”, different colors for the same star among others, being the main responsible the CCD color matrix . The stars also have all a which had strange spike that was in the extremity of Toucam's 1.25” adapter.
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| Vega exp: 3.3 mi (10x20s) Resolution: 4,6" mag. visual 4 Telescópio:Takahashi SKY90 f/2.8 (250mm) camera: Toucam SC 40% gain Takahashi P2Z |
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| Vega exp: 3.3 minutos (10x20s) Resolution: 2,3" mag. visual 4 Telescópio:Takahashi SKY90 f/5.6 (500mm) camera: Toucam SC 40% gain Takahashi P2Z |
05/10/2004
Local:Pousados - Alcanede
A moonlight night
Session at the place where Pedro Mota makes a good part of its images (that can be seen here).
Although if it cannot considered an excellent sky, having about 5-5.5 of zenithal limiting magnitude , it is enough to observe and photograph all the type of objects with exception of really faint one'st, or the ones that do not emit at h-alpha.
The Moon was two thirds illuminated and had born shortly after 22:30, but such fact did not stop us to leave close to the 6 AM, already with the chickens well waked up (the rooster was somewhat on the French hour fuse).
Been there I, Mário Santiago and our host Pedro Mota, respectively, with a Tak Sky90 and P2Z, a STF Mirage7 Deluxe on a Orion SkyView, and the TMB 105mm on a Losmandy GM8 Gemini.
We essentially were entertained making images, more particularly made some tests with color webcam and with the Nikon D70, and to attemped to place the "Crescente Nebula " in the CCD frame until the break for a snack of stakes and baked chouriço, prepared by Pedro's Father.
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| "Sr. Mário" e "Sr. Mota" A double at double stars. One was the autofocus and filter whell motor and the other a realtime FWHM analyser. This duo was only happy with one pixel stars. |
Yet another solo photo of M31, a bit influenced by the moonlight. The contrast improved significantly against previous photo at the Patio.
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| M31, M32 e M110 exp: 1x300s iso 800 (mode3) resolução - resolution: 4,2" instrument(o):Takahashi SKY90 f/4 (360mm) câmara: Nikon D70 Takahashi P2Z |
After returning from the snack, Moon was quite high, Pedro loaned his Atik 2HS and an h-alpha filter to make the images below, while he and Mário were capturing several double stars using filter “cocktails”.
The h-alpha filter heavly cuts light, as do so to light pollution or moonlight, but it was noticed gradual loss of contrast as the the Moon was going up. To notice that the Moon was only about 30 degrees distant of the photographed objects. Although the images in h-alpha usually measure in hours and not in minutes, the images below resulted somewhat likeable. Both would benefit of darker, less turbulent sky, and bigger individual sub-exposures.
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| Barnard 33, NGC 2023 & IC 434 Takahashi SKY90 f/4 (360mm) Atik-2HS 4,3" 60% Takahashi P2Z exp: 34 minutes (14x60s+10x120s) h-apha |
The Orion nebula region, Messier 42, is simultaneously extremely bright and extremely faint, being one of the most complicated objects to capture and process, because its the enormous gamma interval. The filter h-alpha prevented the saturation of the stars and captured thinner detail , having used in the cauldron of “stacking” exposures that ranged from 3 seconds to 2 minutes. It is possible to discern 3 stars from the trapezium (making zoom), despite the image's low sampling resolution.
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| M42 Takahashi SKY90 f/4 (360mm) Atik-2HS 4,3" 60% Takahashi P2Z exp: ~ 18' (1x120s+10x60s+11*20s+11*10s+12*5s+4x3s) h-apha mag. visual 4 (lua 65%) |
The end of the night was of visual relax at the planet Saturn, but still with the Mário doing images of the Moon and also of Saturn. It had moments that TMB was very good. In the Sky90 the ExtenderQ was necessary (a extensor 1.6x for short focal ratio Takas like the Sky90 and the FSQ106) to eliminate the remaining portion of the chromatic aberration, 250x the image was for me exempt from any notorious defect, observing with it the Cassini division, detail on the globe and at least three satellites when the turbulence allowed, even using the unpropriate prismatic diagonal that added some astigmatism, dust and moistness to the optical train.
Then I returned home and notice (one more time) on the authentic quagmire of fog and cloudsat at north of the Mountain range of Aire and Candeeiros. The speedway A1 cuts this mountain range that seems to function as Great Coral Recif, leaving all the clouds to the north of it - unfortunely to me…
01/10/2004
Using setting circles
Although the setting circles had almost become a mere decorative apparatus and also almost vanished from the modern mounts, they had not stopped of being a usefull and convenient tool to point a telescope at a object using its equatorial coordinates. They are also usefull at broad daylight to point a telescope to bright planets or comets on the twilights.
The setting circles were the first form of GOTO used with altazimutals mounts and equatorial mounts.
The method that I use is described below and applies to the Takahashi P2Z mount, which has circles that although of small diameter, are ingraved with precision, however sufficiently similar to its application in any another mount that possesss them.
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| The P2Z setting circles |
The declination circle (above in the photo), has engraved 4 times the scale of 0 to 90 degrees, with 10 degrees divisions and 2 degrees sub-divisions. It can be considered of low “resolution”, but if more was subdivided would be certainly difficult to read with faint light. However, it allows a good percentage of success with an eyepiece that provide fields greater than 1 degree. It is only necessary be adjusted once at start, and generally is fixed permanently with two or more screws.
The right ascension circle has a scale numbered 0 to 24 hours, being each one of the hours subdivided with 10 minutes sub-divisions, that seem to allow better precision, but due to nature of this coordinate (always in movement), it does not become less prone to error. This circle in contrast of the declination is (and it must) be freely rotated, having only one screw to lock it lightly.
To use the setting circles it is absolutely indispensable that the mount should be polar aligned as accurate as possible in order that the successive pointings do not accumulate too much errors. The way to get a good alignment varies from mount to mount, some requiring that should be leveled, or any other procedures.
Using only the declination circle
The simplest way to use the graduated circles will be only using the declination circle. The declination of the stars and deep sky objects does not vary with the time (during a good handful of years at least), therefore its reading on the mount is always correct.
This is also the first step of the complete method, but that it can already provide some help pointing the telescope.
The P2Z's graduated circle are 0-90-0-90 type (others exist like 0-360 or 0-180-0), it could be necessary to the reading at declination 0 (celestial equator), and from there to to go up or down with the telescope tube according to the declination is positive or negative, moving the tube until the hand marks the object's absolute declination value. If if to know vaguely where is object located in the sky, is simply enough to point the tube in rough way, and then refining using the circle.
With the declination coordinate already setted , it will be enough “to sweep” in right ascension along the region of objecto to observe until its detection. This method has good effectiveness at objects that are inside of the limits of detection of the instrument (and the observer), being enough only know object's declination and it's general location on the sky.
Using both circles
This is the complete method that consists of the previously described step, but also adjusting the mount on the right ascension axis.
The quickest way, but not necessarily the unique, will be first pointing visually to a known bright star at the object's neighboring area, even if some ten of degrees distant, AS LONG the star is at the same side of the meridian, or on other words, the telescope tube cannot cross the meridian when moving from the chosen star to the object.
This is explained that when crossing the meridian would be necessary to add (or to deduct) 12 hours to the values that are read at the R.A. circle, and also 180 degrees to the declination axis. In the case of the P2Z this problem in the declination axis would not be dificult to calculate, but on the right ascension would be necessary to add in + - 12 hours. These calculations would complicate the reads and future markings without an obvious advantage.
After placing the star on the center of the field, engaged the R.A. engine adjust the R.A. circle by marking the coordinates of the chosen star. The declination circle will not be necessary to adjust, because it shoud be correct (safe if not correcty marked and locked).
From this moment it will be enough to rotate the mount on the two axis to the desired object coordinates, to lock the axis, and then should the object be in the center of the field or very close. It must be used an eyepiece it at least 1 degree of FOV, bigger the better, due the graduations subdivisions can be dificult to extrapolate decimal values.
The R.A. circle rotates simultaneously with the mount, at the rate of 15 degrees per hour, or a degree for each 4 minutes, so before passing to the following target, must again the circle for coordinate R.A be adjusted with the current target coordinates, proceeding then the move in order to mark the coordinates of next target, doing as it was described on the previous paragraph.
and they work....
This type of circles does not require any calculations, being enough to know the coordinates of some bright stars and the targets to observe, information that is available on any good observation manual, and of preference on the same page. With practice, its effectiveness is impressive, but at the beginning it's convenient to be prepared for several failed attempts, therefore it must pratice first with bright stars and other bright known targets.
This type of pointing obviously can (or should) be combined with “star-hoping” or any another method, being a good alternative (cheap and autonomous) to the computerized systems such as digital GoTos and circles, to find asteroids, comets, objects close to the limit of deteccion, or when objects are invisible with naked eye, being really faint or effect because of the light pollution, being also convenient for astrophotography, especially to avoid taking off the camera to point the telescope.