Monday, March 4, 2019

Hortensius Domes - Znith Observatory Region of Interest

The lunar dome site in Hortensius is one of my favourite region to study. It is found near the 7 km crater Hortensius in Mare Insularum. The area presents six very interesting domes considered by many as typical examples of lunar mare domes.  Their shape is generally broad, convex and semicircular with a low topographic relief. For some reason, these domes bear no specific names other than Greek letters (Phi, Tau, Sigma, Omega, and two smaller domes that are not named).

Mare Insularum region. Image taken on 3 May 2015 using C8 and DMK monochrome camera

The evolution of the Hortensius domes is still poorly understood. The formation of mare domes understood to be caused by eruptions of more viscous and more silicic lava than normal mare basalts. These domes probably formed during the later stages of volcanism on the Moon, characterized at the time by a decreased rate of lava extrusion and comparably low temperature eruptions. Due to the low relief of the Hortensius domes, it is difficult to determine their exact dimensions using normal photogeologic techniques, such as shadow measurements.

Location of individual lunar domes near Hortensius crater (lower left)

Monday, February 4, 2019

A first for Malta - Discovery of a new eclipsing variable star in the constellation Perseus

Double Cluster in Perseus. Credit: N.A.Sharp/NOAO/AURA/NSF

I am pleased to announce the publication of the first discovery of an eclipsing binary star system from Malta in the peer-reviewed Open European Journal of Variable Stars. 

The discovery of this binary star system was made by Stephen M Brincat. Stephen, Winston Grech and myself have then carried out photometric studies on this star system to update its orbital details by observing it over a period of two whole years. This research has allowed us to derive other characteristics of this eclipsing binary star system.  Below is a link to the full scientific version of this announcement.

Source:European Space Observatory

Source: Brincat, Galdies, Grech, 2019.

Published announcement:

Brincat, S. M., Galdies, C., Grech, W. (2019) A new binary star system of EA type in Perseus: UCAC4 735-019611. Open European Journal on Variable stars. January 2019. ISSN 1801-5964. 7pp

Discovery of a new binary star system (UCAC4 735-019611 = USNO-B1.0 1469-0068570 = 2MASS J01561032+5657563) in the Perseus constellation is presented. The shape of the light curve and its characteristics (period of 2.12701 ± 0.00001d, amplitude of V=0.55 mag, initial minimum period epoch HJD 2457363.37784) indicates that the new variable star is an eclipsing binary of Algol (EA) type. We registered this variable star in the International Variable Star Index (VSX) and its AAVSO UID is 000-BLW-283.  

Friday, January 11, 2019

Observing 3 salient asteroids for more than 80 hours

Source: NASA

The last issue of the scientific journal - the Minor Planet Bulletin has recently published our work on the calculation of the rotational period of 3 asteroids, namely, 232 Russia, 1117 Reginita and (11200) 1999 CV121. 

Observations were collected through collaborative campaigns between the months of 2018 April and July by Winston Grech, Stephen M Brincat and myself.

These campaigns amount to over 1000 photometric images with a photographic exposure that ranged from 4 to 6 minutes per image, giving a total of more than 80 hours of observation time.

The asteroid 232 Russia resides within the inner asteroid belt between Mars and Jupiter while 1999 CV121 (no name has been given yet to this asteroid) is found somewhere within the middle asteroid belt. The asteroid 1117 Reginita is a member of the Flora asteroid family that also resides within the inner regions of the asteroid belt.

This is a link to our scientific paper published in Volume 46 of the Minor Planet Bulletin.

This study is also available through the SAO/NASA Astrophysics Data System:

Saturday, January 5, 2019

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