Wednesday, August 22, 2018

The electric blue crater on our moon.

Photo 1: Aristarchus crater

The region of the Aristarchus plateau has been the site of many interesting observation reports, raising questions about the source of the blue and reddish light from this crater. Such reports document a number of processes seen through telescopes and from manned spacecrafts, including  temporary obscurations and colourations of the surface.

In 1971 when Apollo 15 passed 110 kilometers above the Aristarchus plateau, a significant rise in alpha particles was detected. These particles are believed to be caused by the decay of radon-222, a radioactive gas with a half-life of only 3.8 days. The Lunar Prospector mission later confirmed radon-222 emissions from this crater.

An interesting report published in by the United States Air Force in May 1964 documents the peculiarity of this crater, which was a subject of much debate at the time. The inset below in Photo 2 shows the observation of a reddish hue in the region highlighted in 1963, which is similar to the area I observed in photo 1 above. This report is available here. This is apart from the strong blue colour in the remaining parts of the crater. This observation discredits those who say that the lunar surface is devoid of both colour and phenomena.

Photo 2: Source - United States Air Force, 1964.

My image is composed of individual colour channel images and overlayed to create an RGB composite. Blue and Magenta colours were slightly enhanced to bring out these two colourations in the crater. The final image was cropped to reflect changes in the immediate vicinity and interior of Aristarchus crater.

During the 4 minute period, a weak red colour on the southern part of the inner walls of Aristarchus was evident, similar to that reported in 1963 by Greenacre and Barr. The remaining parts of the inner walls and crater floor looked normal.

However, a trace orange-red delineation is evident on the northwestern part of the inner walls.

Equipment & Software Used:
Nexstar 8SE at f10
DMK 31AF  monochrome
IC Software
Astronomik filters  R – G – B - CLS
Astrodon IR Pass 742

Atmospheric conditions @ 1800UT:
Ambient air temperature: 24degC
Dew point: 22degC
Wind: 04 knots SSW
Haze visible, 8km visibility
Clear sky

Saturday, August 11, 2018

Hellas basin is bright and prominent.

A total of 5000 images per channel at a frame rate per second higher than 120 were acquired, out of which the best 100 images were stacked to produce these images. South is at top.

It is summer in the Martian southern hemisphere. Hellas basin is quite conspicuous and bright, dominating the southern hemisphere. The interesting protruding albedo of Syrtis major from the southern to the northern hemisphere is also evident but the fine detail I observed during other apparitions is not present in these latest images. The south polar cap is also evident. The atmospheric turbulence at the current low altitude of Mars in our skies is not helping planetary imagers at our latitudes to produce better images of Mars.

This observation has been archived on ALPO servers in the US and Japan.

Comments are welcome

Tuesday, August 7, 2018

A rewarding imaging session of Mars.

Albedo features on the red planet are slowly becoming more visible. However, the planet now started to recede away from Earth. At the time of imaging, the diameter was 24.3" at the equator.

The IR pass filter is showing us some more detail. We can see the bright Hellas area at 11 o'clock, the south polar cap at 12 o'clock (with the lateral streak somewhat visible), and Sinus meridiani promontory in the center. Arabia is the huge expanse in the southern hemisphere with no albedo features. Niliacus Lacus is somewhat visible at 5 o'clock position. South pole is at top according to ALPO imaging convention.

This observation has been archived on ALPO servers in the US and Japan.

Comments are welcome.

Wednesday, August 1, 2018

Let the dust settle on Mars

Surface albedo of planet Mars under moderate seeing conditions

First light through my new ASI290MC. This camera generates huge data, with around 1GB per 4000 images, and frame rates as high at 200fps, even though PC USB port is 2.0.

Seeing conditions are not favourable so far. Mars is quite low in the sky, even at its culmination. At this low elevation in the sky, our atmosphere is quite turbulent. Another thing that is not favouring crisp imaging is the extensive dust still present in the martian atmosphere. The situation is now improving when compared to a month ago