Archive for the ‘Double stars’ Category


Double star marathon?

February 20, 2012

An invaluable aid to me when I am working on an observing program is an all-sky map showing the distribution of the things I’m trying to find. The maps of the Messier objects and Caldwell objects from Wikipedia are my constant companions when observing: I printed them in color on 11×17 paper, folded them in half, and stuffed them in sheet protectors.

When I started on the Astronomical League’s Double Star list there was no similar all-sky chart for the 100 double and multiple stars on the list,  so I made one, using the Wikipedia Messier sky chart as the basis:

When I had them all mapped, I noticed that by and large they follow the distribution of the Messier objects, especially in having a big gap to the south between 22 hours and 5 hours right ascension–just the area blocked by the sun and horizons in March and April. I fired up Stellarium and drew on the sunset and sunrise horizons for southern California around the end of March:

Only one of the 100 double stars on the AL list is below the horizon at that time. So during Messier Marathon season it should be possible to do a double star marathon as well, and try to split 99 of the 100 AL doubles in one night.

A double star marathon would bring interesting opportunities and challenges. With Messier marathons, the primary enemy is the moon: you have to go within a very few days on either side of the new moon, or the moonlight will drown out some of the fainter objects. But the relatively bright double stars on the AL list would punch through a fair amount of moonlight. You still wouldn’t want to go between first quarter and last quarter, probably, or the moonlight would wash out some of the guide stars you’d need to find your way, but the window of opportunity should open from six or seven days around new moon to about two weeks.

On the flip side, in a Messier marathon the seeing isn’t that crucial because you’re observing big, extended objects, and just trying to log them, not necessarily tease out details. But to split some of the tighter double stars requires reasonably good seeing, and there’s no way to predict that in advance, sometimes not even from early evening to midnight or midnight to dawn. So the Messier marathon has a tighter constraint from the moon, but it’s predictable, whereas the one sky condition that could make or break a double star marathon (at least for a crucial few of the tightest doubles) can’t be predicted in advance.

I first raised the possibility of a double star marathon a couple of years ago on Cloudy Nights. As far as I know, no one has attempted one. I haven’t, for a couple of reasons. First, if I get to a dark site at Messier marathon time and can afford to stay up all night, I’m going to run a Messier marathon. Second, it’s precisely because double stars punch through light pollution so well that I tend to save them for observing from home–no need to waste my dark sky time on something I can see from my driveway, and my driveway does not have good enough horizons to attempt a marathon of any kind. But I suppose I could head up to the top of the local parking garage and try a double star marathon from there. It wouldn’t require a long drive to dark skies, just a free night followed by a day with few responsibilities.

If I ever get around to it, I’ll let you know.

Related: my free logbook for the AL Double Star Club is on this page, and I have a bunch of Messier Marathon tools here.


Mt Wilson: even better the second time around

June 14, 2010

About a dozen of us from the Pomona Valley Amateur Astronomers spent Saturday night observing with the 60-inch telescope up on Mount Wilson. A really excellent night on the mountain is a Goldilocks affair–you need enough of a marine layer to cover up the lights of LA, but the fog has to stay low enough not to swamp the observatory itself. The PVAA visited Mount Wilson last summer, but got fogged out. That worked out okay for me, because they rescheduled for the fall and I found out about the trip in time to go along.

Saturday night the marine layer was looking  pretty good when we got there. Unfortunately, it cleared out before midnight, so the sky was too bright for us to do any serious galaxy observing. But we saw quite a few planetary nebulae and globular clusters, which punch through the light pollution better than most galaxies.

We saw a lot of burnt trees on the way in, from last fall’s Station Fire, which at one point threatened the observatory. The trees by the gate had some light charring down near the bottoms of their trunks, but they hadn’t burned very high or very hot, and I suspect that the fire evidence I saw there was caused by backfires set by the firefighters who saved the observatory.

The 60-inch telescope, largest in the world from 1908 to 1917, is as impressive as ever.

Our first target was Saturn. Although the seeing settled down later in the evening, right after dark the sky was pretty turbulent and that cut down on the amount of detail we could see. Also, and to my immense irritation, I couldn’t get my camera to focus with the optical zoom engaged, so I couldn’t  increase the object size on the CCD as much as I would have liked. This photo doesn’t really do the view justice–in fact, it’s not much better than I’ve done with my 10-inch scope from my driveway (proof here).  Remember that this is a sad comment on the state of the just-past-sunset atmosphere and my finicky camera, and not a slight on the telescope, which is capable of much better!

But things did get better as the evening progressed and we saw tons of cool stuff. Several other people were experimenting with their own digital cameras and that inspired me to try some things I haven’t done before, like photographing double stars. Here is Albireo, a summer favorite that is easily split by even small telescopes.

We started with Saturn and ended with Jupiter; the King of the Planets was climbing in the east as the sky started to brighten before dawn. If you haven’t looked at Jupiter in a while, the Red Spot is actually red again, and the normally-brown South Equatorial Belt has faded almost completely. This is a big switch from the past year or two, when the “Red” Spot has mostly been visible as a white notch in the SEB. It was far and away the best look at the GRS that I’d ever gotten.

The highlight of the evening for me was seeing M13, the Great Globular Cluster in Hercules, and M5, another excellent summer glob, back to back. M13 is probably in most deep sky observers’ top ten, but some people like M5 better, and I’m in that camp. M5 isn’t quite as big or bright, although it comes very close, but it has a much more compact core and the outer stars are arranged in loops and swirls rather than radiating chains. To my eyes, M5 looks like an explosion of stars, in progress. It’s good in my ten-inch scope. It’s phenomenal in the 60-inch.

Last fall we went on a weeknight and I had to leave early, around 3:00 AM or so, to get up to teach the next morning. We also had a considerably larger group, so we didn’t get through as many objects per unit time. Obviously going with a big group is better for the club, but it was nice to have a more intimate group and a shorter line at the eyepiece. I had a heck of a good time, and I plan on going back up every chance I get. If it’s within your means, you should do likewise.

Many thanks to our host and telescope operator for another tremendous evening!

Update: I’m kind of a doofus. If you were wondering why this post is included in the binocular category, it’s because I took my 15×70 bins with me and did some deep-sky observing out of the opening in the dome, while waiting in line for the eyepiece. I bagged four targets for the AL Deep Sky Binocular club, which leaves me with only six more needed to complete that list. But I forgot to mention all of this when I first posted!