Observing-Challenge-Apr-2009

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Ottawa Centre Monthly Observing Challenges

Beginning in 2007, Ottawa Centre introduced a new item to its monthly meetings: an observing challenge object. Each month the centre will post a description of an interesting object. Members are invited to observe, sketch, photograph, or otherwise learn about this object. At the subsequent monthly meeting, an agenda item will provide an opportunity to share your thoughts, photos, sketches, or comments.

April 2009

Lunar: Lacus Mortis & Crater Burg

by Murray Campbell and Brian McCullough

This month's Lunar challenge is number 36 in RASC's Isabel Williamson Lunar Observing Program, and is detailed on R√ľkl Chart No. 14.

Find and observe Lacus Mortis, the "Lake of Death", located above the well-known Mare Serenitatis. Lacus Mortis
Image: Lee Macdonald
This image by member Mike Wirths shows the numerous craters and other features in this area. Murray suggests observing at different times during the month, as shadows coming from different directions will highlight different features.

Murray mysteriously challenged members to locate and describe "the Cross of Death", but declined to provide any further hints as to what or where this is.

Lacus Mortis
Image: Mike Wirths

Deep Sky: Count Galaxies in the Virgo Cluster

by Rolf Meier

This month's deep sky challenge is to count the number of galaxies you can observe in the Virgo Cluster, in the neighbourhood of M86 and M84. For visual observers this challenge requires a moderate-sized scope (12" aperture or more) and dark skies.

Rolf gave, as a challenge, the extremely rich field of galaxies known as the Virgo Cluster, located between Virgo and Leo. Rich field of galaxies in the Virgo/Leo region
Image: Norton Star Atlas
Find the constellations Virgo and Leo in the late evening sky. Constellations Virgo and Leo
Image from Starry Night
Find Denebola, the rearmost star in Leo, and Vindemiatrix, the uppermost star in Virgo. Point your telescope halfway between these two stars. Go-to users can select Messier objects M86 or M84. Point halfway between Denebola in Leo and Vindemiatrix in Virgo
Image from Starry Night
This star chart shows the large number of NGC galaxies near the Messier galaxies M84, M86, and M87. Rich field of galaxies in the Virgo-Leo region
The line of bright galaxies surrounding M86 is known as Markarian's Chain. Markarian's Chain - galaxies surrounding M86
The DSO challenge is to centre one of the bright Messier galaxies M86 or M84 in your eyepiece and then count how many other galaxies you can detect in the field. Markarian's Chain - galaxies surrounding M86
Rolf suggested trying this with both low and high magnification eyepieces. Low magnification will bring more galaxies in because of the wider field, while high magnification will bring more galaxies in by making smaller and fainter galaxies more visible.

Report back to the next meeting with your observations and comments, and with the number of galaxies you were able to detect.

Markarian's Chain - galaxies surrounding M86
Image courtesy Ken Sperber


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