The Barrow crater ray

[jetstream]

The other night the seeing conditions were fantastic and many lunar features were observed.I have been chasing the central rille in the Apline Valley,but no luck yet.During breaks of hard observing,I cruised around the lunar surface looking for anything interesting.And then I came across this crater with a bright sharp section across it.Now days later and with help from YKSE the feature is identified as the Barrow crater ray.Very unique and well worth finding again if possible.

[romx]

Awesome image, thx for sharing

[baggywrinkle]

Very nicely drawn.

How long does something like that take?

[jetstream]

I can take no credit for the sketch,after searching for a representaion of my observation this is the best fit.I wish I could sketch...Searching for and then identifying objects in the dob is a slow but rewarding process for me,I have seen lots of things I have yet to identify out there The galaxies in Virgo for instance are going to take repeated views for me to sort them out.A person does learn the sky this way though!

[cotterless45]

Another good target is the row of craters along the edge of the Alpine Valley, really neat, Nick.

[John]

Another good target is the row of craters along the edge of the Alpine Valley, really neat, Nick.

Yes thats a nice one. If thats the little row of craters on the floor of the valley, nearer to one side, then the central rille runs right by it.

Nice photo of the Alpine Valley with the rille here:

https://the-moon.wikispaces.com/Alpine+Valley+Central+Rille

A couple of other nice features I was observing over the past couple of nights are Rima Birt, a small winding rille near the Rupes Recta and Birt crater and a really interesting 300km long straight cleft / fault called Rima Hesiodus which seems to run straight as a die and cuts right through some uplands areas.

[AlexB67]

.I have been chasing the central rille in the Apline Valley,but no luck yet.During breaks of hard observing,

You are not alone Gerry. The other night when I was looking earlier in the evening before switching to Mars, I shall try again when the skies are at their best and the scope has been out for a longer time as I had during the mars observing period. I do feel though looking at the width of the thing it would be pushing the resolution limits  of what can be seen in a 10 inch Dob (I am suspecting), so I would be stoked if I managed to bag it, but not sure I will. Of course, could also be my eyes are not be up to it, who knows.

Of course a very good mirror, great eyepieces  and good seeing and contrast  will help, but the simple theoretical lunar resolution of a 10 inch Dob is wider than that by some bit. Not tried it at 360x which I did use on the plato craterlets, but not sure it is just insufficient mag thing or not in case of the alpine rile,   I can push to 400x if needed with me good old cheapybarlow to see what happens, not tried that so far.  5mm BGO, 2x barlow, May not fit much in there but surely plenty enough for the valley

We keep plugging away

[John]

The rille has been spotted with a 6" F/8 refractor:

http://stargazerslounge.com/topic/213405-alpine-valley-rill/

So it should be feasible with an 8" or 10" dob under the right lunar illumination and seeing conditions.  

[jetstream]

I have just heard that lunar "libration"(?) may play a role for choosing optimum rille viewing,not sure.Looking for excuses somewhat as my seeing the other night was so good,with the terminator right there, but no go on the rille.YKSE kindly gave me this link to help me in the pursuit http://www.shallowsky.com/moon/ and any other advice is much appreciated.Scope was well cooled,collimated and various quality EP's were tried from 200x-400x,with an emphasis on 240x(5mmKK) and the 3-6 Nagler zoom at various settings.The KK is sharper than the zoom.

[AlexB67]

We had better get  on with it and find it Gerry   I've had two goes at it but not for long periods, nothig as serious as my efforts on plato craterlets, so John's post gives me hope. I founds for example after a half hour scope cooling Plato craterlets were hard to see, in fact at the beginning not at all, then as the night went on and scope setted more they became clearer bit by bit and quite obvious features. Hopefully the rile will do something similar and just pop out one day.

Cheers for the link btw, that looks very interesting webpage. I use virtual moon atlas a lot to pick my stuff.

[jetstream]

Alex,I use the fan to cool my mirror much faster than without, as my scope is stored inside.Maybe this is an option for you as well.I have been trying for quite a while for the rille......my seeing is usually not that great but lately it has been excellent.Controlling the thermals is also important,they can come from unexpected places and really mess me up.Well I would love to bag the rille for sure,but I console myself with the fact that we have a long time to try.... I am also going to try the features mentioned in this thread,lots of fun