Double star: Mintaka (34-Delta Orionis)

Mintaka (34-Delta Orionis): Double Star in Orion • SCT 8" f/10 • 200mm Celestron widefield eyepiece • 100x • 12 January 2010 • 20:30 UT • Seeing 7/10 • cloudy

This is my first attempt to sketch a binary star according to the technique used by Jeremy Perez.
http://www.perezmedia.net/beltofvenus/archives/000567.html

There are still a lot of things to master, including the representation of the relative magnitudes as well as astrometry to accurately monitor angular separation.

Mintaka is the westernmost star of the three belt stars of Orion, also known as Delta Orionis. It is a beautiful double star. The companion star is located 52.6" almost due north of the primary in position angle 359°. Both stars were seen as whitish blue.

RA = 5 h 32 m 0.4 s Dec = - 0 ° 17 ' 56.7 ''
(Equatorial coordinates - epoque J2000 - ICRS)
Color index B-V : -0.17
Spectral class : O9.5II

The separation between the two components of Delta Orionis made it fairly easy pair to separate in spite of the brilliance of the primary star. I used a  20 mm Celestron Plossl eyepiece (100x) for the sketch shown here on the left.

Mintaka has been known since antiquity. Its duplicity was documented in F. G. Wilhelm Struve's first supplement to his famous catalogue and bears the designation STF I 14.

MARS 12TH JANUARY 2010

I am still trying to find the right sketching technique to record Mars. Sketching under a faint red light is never easy especially if apart from the sketching pad you need to hold graphite pencils, a blender, a graphite stick and an erasor shield. So the more complicated the technique is the less practical it becomes. One needs to find a balance between the two.

It was rather unfortunate that surface of Mars did not show too much detail except for the NPC, Mare Cimmerium, Mare Sirenium and Mare Boreum surrounding the North Polar Cap. According to members of marsobservers yahoo group, CCD images of Mars are showing some streaking in the polar cap.

The seeing conditions tonight where far from ideal. There was slight to moderate wind, cloud patches and the weather is under the influence of low pressure system with neighbouring high jet streams. Through the eyepiece Mars was most of the time fuzzy and was difficult to identify any other surface features in the polar cap or in Mesogaea region.

Below is the original sketch next to an intensity sketch.

MARS 7TH JANUARY 2010

Mars is getting closer now and it is amazing how much detail can be seen from even a small telescope with medium seeing conditions.

During my short observation the first albedo feature which struck me most was that dark fringe of Utopia and its elongated feature pointing towards the centre of ths disc. Utopia always contrasts well against the adjacent whitish polar cap. Also evident during moments of good seeing was Alcyonus Nodus but was rather elusive at times.

The next obvious feature was seen on the opposite side of the disc corresponding to the dark albedo strip of Mare Tyrrhenum underneath which Eridiana was seen as a somewhat lighter area. Unlike in the 2003 Mars apparition, I could not detected any fine detail of this very interesting M. Tyrrhenum.

Next I surveyed the neighbourhood of A. Nodus, in which I detected another subtle albedo feature corresponding to the location of Sympallus Lacus. I could hint that between A. Nodus and S. Lacus there was a circular, lighter area, which interestingly enough is also represented in the Calsky apparent view. Could this be part of Elysium?

During good visibility, Utopia seemed to be closely touching S. Lacus, and in my sketch I slightly connected the two.

At almost the end of the sketching period I started noticing a dark feature at the edge of the disc which the following morning my mars map showed it to be the dark Syrtis Major. It was quite a well defined dark and elongated feature.

The following morning I checked my sketch against Calsky's apparent view as seen through an 8 inch scope (selection for other apertures also provided) and I was really happy to note the good accuracy of the sketch.

Below is the original albedo and intensity sketch I made next to the telescope. The Mars map needs to be rotated horizontally.

LUNAR CRATER RAMSDEN

This evening I have focussed my scope on Ramsden - a lunar impact crater located on the western stretch of the Palus Epidemiarum.

The floor of this 25km crater has been flooded with lava, which this evening was in total darkness. The rim looked oval in outline, with depressions along parts of the walls. Ramsden is 2km deep and lacks terraces, central peaks, and any ray system.

In my sketch I tried to bring out the delicate rille system that form part of the Rimae Ramsden system. These rilles span an area 130 kilometers across, sprawling over the western Palus Epidemiarum. A branch reaches northwest to the Mare Nubium, passing between the craters Campanus and Mercator.

All in all, Ramsden and its surrounding rille system was a worthwhile sketching experience.

Above right is a picture of Ramsden for reference, taken from the LOPAM database.